Javascript is currently disabled in your browser. When javascript is disabled, some functions of this website will not work.

Open access for scientific and medical research

From submission to the first editing decision.

From editor acceptance to publication.

The above percentage of manuscripts have been rejected in the past 12 months.

Open access to peer-reviewed scientific and medical journals.

Dove Medical Press is a member of OAI.

Batch reprints for the pharmaceutical industry.

We provide real benefits for authors, including fast processing of papers.

Register your specific details and specific drugs of interest, and we will match the information you provide with articles in our extensive database and send you a PDF copy via email in a timely manner.

Back to Journal »Journal of Inflammation Research» Volume 14

The adverse effects of incense on human health: from mechanism to effect

Author Lee CW, Vo TTT, Wee Y, Chiang YC, Chi MC, Chen ML, Hsu LF, Fang ML, Lee KH, Guo SE, Cheng HC, Lee IT 

Published on October 22, 2021, the 2021 volume: 14 pages 5451-5472

DOI https://doi.org/10.2147/JIR.S332771

Single anonymous peer review

Reviewing editor: Professor Quan Ning

Chang-Wen Lee,1– 4,* Thi Thuy Tien Vo,5,* Yinshen Wee,6 Yao-Chang Chiang,1,2 Miao-Ching Chi,7–9 Min-Li Chen,10,11 Lee-Fen Hsu ,9,12 Mei-Ling Fang,13,14 Kuan-Han Lee,15 Su-Er Guo,11 Hsin-Chung Cheng,5,16 I-Ta Lee5 1 Department of Nursing, Department of Basic Medicine, Chronic Diseases and Health, Chiayi County, Taiwan Puzi City Chang Gung University of Science and Technology Chinese Herbal Medicine Promotion Research Center and Research Center; 2 Department of Orthopedics, Chang Gung Memorial Hospital, Puzi City, Chiayi County, Taiwan; 3 Department of Safety, Health and Environmental Engineering, Ming Chi University of Technology, New Taipei City, Taiwan; 4 Taoyuan City, Taiwan Chang Gung University School of Medicine; 5 Taipei School of Dentistry, School of Stomatology, Medical University, Taipei, Taiwan; 6 Department of Pathology, University of Utah, Salt Lake City, Utah, USA; 7 Chronic Disease and Health Promotion Research Center, Chang Gung University of Science and Technology, Puzi City, Chiayi County, Taiwan; 8 Chiayi Chang Gung Memorial, Puzi City, Chiayi County, Taiwan Department of Pulmonary Diseases and Critical Care Medicine; 9 Department of Respiratory Medicine, Chang Gung University of Science and Technology, Puzi City, Chiayi County, Taiwan; 10 Department of Nursing, Chang Gung University Hospital, Puzi City, Chiayi County, Taiwan; 11 Graduate School of Nursing, Chang Gung University of Science and Technology, Puzi City, Chiayi County, Taiwan; 12 Puzi County, Chiayi County, Taiwan Department of Surgery and Neurosurgery, Chang Gung Memorial Hospital; 13 Research Center for Environmental Toxins and Emerging Pollutants, Cheng Zhao University, Kaohsiung, Taiwan; 14 Ultramicro Research and Technology Center, Cheng Zhao University, Kaohsiung, Taiwan; 15 Department of Pharmacy, Jianan University of Pharmacy, Tainan, Taiwan; 16 Taipei, Taiwan Department of Dentistry, Taipei Medical University Hospital* These authors have contributed equally to this work. Corresponding author: Li Yi University School of Dentistry, School of Stomatology, Taipei Medical University, No. 250 Wuxing Street, Taipei 11031, Taiwan 886-2-27361661 extension. 5162 Fax 886-2-27362295 Email [email protected] Abstract: Burning incense is a very popular activity in daily life around the world. More and more epidemiological and experimental evidences report the negative effects of incense use on human well-being and pose a potential threat to the public. This work is a comprehensive review that covers the latest findings about the adverse effects of cigarettes on our health, and provides a panoramic visualization from the mechanism to the impact. The toxicity of cigarettes comes directly from its harmful ingredients and its ability to deposit in the body. In addition, oxidative stress and related inflammation driven by reactive oxygen species seem to be possible underlying mechanisms that trigger various adverse reactions. Although there are still many gaps in our current knowledge, this question still has some important implications. Keywords: incense, oxidative stress, inflammation, cancer, poison

The word incense comes from the Latin incendere, which means "burn". In fact, incense is an entity that can be burned to release aromatic smoke. Since ancient times, burning incense has been a traditional and common practice all over the world, especially in the eastern region, with different uses. In some religions such as Buddhism, Taoism and Hinduism, burning incense has become an essential ritual practice in daily life. Sacrifice and sacrifice. In addition, incense has been used for other purposes, such as deodorization, aromatherapy, and meditation. 2,3 In general, these practices have led to the widespread use of incense in modern society. It is estimated that the global annual consumption of incense exceeds 200 million tons, of which Asia is the largest market. 4,5 A 2003 report by the Taiwan Environmental Protection Agency showed that 92 temples in Taiwan burned a total of 28.7 metric tons of incense. Kaohsiung City, 6 contributed approximately 3,580 tons of incense consumed by Taiwanese temples each year. 7 It is even expected that more incense will be burned during the climax of religious ceremonies, major festivals and special ceremonies and occasions. In addition to religious and public places, it is reported that nearly 80% of Chinese people burn incense at home every day, and more than 90% have practiced burning incense for more than 20 years. 8 Similarly, according to calculations, 86% of households in the United Arab Emirates burn incense at least once a week. 9 These data show that domestic burning incense also accounts for a large amount of incense consumption. Unfortunately, some people say that the incense will burn slowly and continuously without being completely burned, 10 causing the emission of smoke, and its harmful components will be discussed later. 11 As mentioned above, due to the large consumption of incense, incense burning may be the main source. Outdoor and indoor air pollution. In addition, cigarettes released during the combustion process can be inhaled into the human body and are considered to be equivalent or even more harmful than passive smoking. 2 In fact, there is increasing evidence that there is an association between exposure to cigarettes and an increased risk of many health problems, such as respiratory problems, cardiovascular diseases, and even cancer. 12-14 Now that most people in the world are aware of the harmful effects of smoking, it is time for us to consider another potential threat. Public health and comfort originate from the old-age custom of burning incense in ceremonial venues and homes. However, there are still more questions about the adverse effects of incense on human health, especially its underlying mechanism. Therefore, the goal of this work is to clarify the harmful components of the smoke produced by incense, and to summarize the current state of knowledge about the association between incense and health risks, with a focus on the possible underlying mechanisms of oxidative stress and related inflammation. In addition, the reasonable impact on public health management was discussed. The current review is expected to reveal the remaining gaps and further steps needed to solve this new problem in the future.

Commercial incense comes in many forms, including sticks, incense, cones, rolls, powder, rope, rock or charcoal, and smear bundles. 2 Among them, incense, whose base is a slender wood or bamboo with incense powder 2 has been widely used in many places around the world, such as the Indian subcontinent, Asian countries and the United States. 15,16 Incense powder is generally composed of incense wood, wood and sawdust, coal powder or potassium nitrate and binder. 10,16 During the combustion process, the incense produces smoke, which is characterized by the gas phase consisting of carbon dioxide, carbon monoxide, sulfur dioxide, formaldehyde, nitrogen dioxide, polycyclic aromatic compounds, volatile organic compounds, and a particulate phase defined as particulate matter. 17-19 The incense emission of harmful substances can be divided into inorganic gas products, particulate matter r and organic compounds, as shown below. People exposed to incense may inhale the entire complex mixture of irritants and poisons, posing a major risk to human health. On the other hand, because the function of pulverized coal is to promote smoother combustion, it is the raw material for making incense sticks. Therefore, when the incense is lit, a gray to earthy residue is left, called incense stick ash. 3,16,20 The complete burning of an incense can produce as much as one-tenth of its weight. 10 Importantly, the analysis of incense ash showed the presence of many toxic heavy metals and oxides, including calcium oxide, silicon dioxide, aluminum oxide, ferrous iron, potassium oxide, phosphorus oxide, magnesium oxide, and oxides of trace elements. Further observation of the elemental composition showed the highest percentage of carbon, which may be due to incomplete combustion, soot and volatile organic compounds present in the incense sticks. 10 The structure, chemical and element properties and potential applications of incense sticks. Some recent studies have well reported incense ash. 10, 16, 20 However, research on the properties and effects of incense ash is still ongoing, which is beyond the subject of the current review.

According to the existing evidence on the emission characteristics of incense, the three main inorganic gases identified in incense smoke include carbon monoxide (CO), nitrogen oxides (NOx) and sulfur dioxide (SO2). First of all, carbon monoxide is a colorless, odorless, odorless but harmful gas, which is an inevitable result of combustion. 21 Therefore, it is not uncommon to detect that this gaseous product is incompletely burned during the incense burning process. By using the experimental test room, the calculated CO emission factor varies between 110-120 mg/g incense. 22 In addition, it was found that the peak levels of CO emissions from several common types of incense from different sources exceeded the recommended indoor air quality in Hong Kong office and public space (HKIAQO) standards, two of which were even higher than the U.S. Environmental Protection Agency ( The National Ambient Air Quality Standard (NAAQS) established by the US EPA, that is, 1 hour CO is 35 parts per million. The highest observed CO emission rate and emission factor were as high as 794.7 mg/h and 227.7 mg/g incense, depending on the type of incense. 18 So far, concerns about the potential health effects of exposure to carbon monoxide have been well studied through extensive epidemiological and experimental investigations. The signs and symptoms of carbon monoxide poisoning are usually non-specific between individuals, ranging from headache, nausea and vomiting, dizziness, changes in consciousness, subjective weakness to confusion, myocardial infarction, respiratory failure, loss of consciousness, and even death, mainly caused by exposure The concentration and duration are determined. 23 The main mechanism of CO toxicity is attributed to its extremely high affinity for hemoglobin in the blood. Hemoglobin is an important oxygen transport in the body, resulting in a lack of sufficient oxygen supply, which is called hypoxia. Therefore, tissues that need more oxygen, Tissues such as the brain and heart are more prone to hypoxia. 24 Secondly, nitric oxide (NO) and nitrogen dioxide (NO2) are also known as the most harmful NOx to the human body. Human health is known as the two major nitrogen oxides related to combustion. Since NOx is a low water-soluble irritant, they do not produce mucosal irritation when deposited in the upper respiratory tract, and the recipient may be unaware of the ongoing exposure, with little or no warning symptoms. Some early signs include mild cough or nausea. Prolonged exposure may cause the higher accumulated concentration of NOx to penetrate deeper into the lower respiratory tract, leading to delayed breathing problems. In the case of severe acute exposure, patients may experience shortness of breath, cough, or symptoms consistent with acute respiratory distress syndrome. Under special circumstances, eye irritation may occur after accidental contact of the eyes or related membranes with relatively high NO2 concentrations. 25 Generally speaking, about 90-95% of NOx is emitted as NO during the combustion process, and 5-10% is emitted as NO2. However, under environmental conditions, NO will quickly oxidize to NO2, while in indoor environments, this oxidation rate is slower. Therefore, in some cases, the NO2 level can be regarded as the standard value of NOx. Measurements of nitrogen dioxide emissions from burning incense at two shrines in Chiang Mai, Thailand show that due to the increase in incense burning, the concentration on special occasions is significantly higher than normal. Nevertheless, the level of nitrogen dioxide did not exceed the 8-hour average good-grade nitrogen dioxide concentration of Hong Kong indoor air quality (<0.080 ppm),26 which is comparable to the data of the previous study. 18 In contrast, the peak concentrations of nitrogen dioxide emitted by two different types of Arabs have been recorded as high as 0.1 to 0.3 ppm. In addition, the time-weighted average of the observed NOx levels is 150-200 ppb/h, which is not only higher than the previous environmental tobacco smoke data, but also higher than the government-regulated value of the United Arab Emirates. 11 This may be because Arabic incense requires charcoal as a combustion aid, rather than other forms of spontaneous combustion commonly used around the world. Finally, it is reported that the SO2 emission rate of cone incense burned in a 30 cubic meter environmental chamber for 38 minutes is 25.5 mg/h, and the peak concentration is estimated to be 0.45 mg/m3. Compared with the outdoor SO2 concentration specified in the US EPA NAAQS, SO2 is 1.3 mg/m3, 0.365 mg/m3 and 0.080 mg/m3, a(n) 3-hour average, 24-hour average and annual arithmetic average, corresponding The concentration of SO2 emitted by incense burners may exceed the standard under certain conditions. 2 In recent years, several reviews on the effects of acute and chronic low-dose or high-dose SO2 exposure on human and animal health have been published. In short, sulfur dioxide is not only recorded as a respiratory irritant and bronchoconstrictor, but also associated with cardiovascular disease, leading to increased hospital admissions, morbidity, and mortality for cardiopulmonary problems. 27

Particulate matter (PM) refers to all dust, smoke and haze particles suspended in the environment. In other words, PM can be described as a complex mixture of physically and chemically different particles, such as solids and/or liquid droplets suspended in the atmosphere. The main source of 28 PM comes from human life, especially activities related to combustion. In view of the fact that incense burning is a slow and incomplete combustion process, the incense burning process can produce a large amount of PM. In fact, a survey conducted in a temple in central Taiwan found that during the reburning of incense, the concentration of different PM components increased significantly, 29 consistent with other studies. 30-32 Similarly, it is found that burning incense in an indoor environment will produce an average of more than 45 mg of PM per gram of incense burning, while cigarettes are about 10 mg/g. 33 Similarly, the characteristics of PM emissions from incense burning report that the emission rate and emission factor range of the PM fines are 7 to 202 mg/h and 5 to 56 mg/g of incense, respectively. 2 It is worth noting that the PM emission levels of 10 common types of incense produced in different regions significantly exceed Hong Kong's indoor air quality indicators, regardless of the type. 18 From the perspective of health effects, PM can be measured according to its aerodynamic diameter. Classification, because the smaller the particles, the deeper they can penetrate, the more damage they may cause. PM usually has two basic particle indicators, the so-called coarse particles and fine particles. In addition, the smallest particles found so far are called ultrafine particles, usually smaller than a few hundred nanometers. 34 Convincing evidence shows that exposure to these particles (especially fine particles and ultra-fine particles) is associated with hospitalization rates, morbidity, 28,35 It is worth noting that the World Health Organization (WHO) specialized cancer organization, namely International Cancer The Institute of Research (IARC) stated that exposure to PM can cause lung cancer, leading to its classification as carcinogenic to humans since 2013. 36 So far, more and more studies have also proved that there is a positive correlation between the increase of PM exposure and the increase of cancer risk in other parts, which is summarized in our recent work. 37

The aroma substances present in the incense are generally derived from plant extracts. Many types of fragrant woods, resins, herbs, and essential oils can be used alone or together to provide aromas to incense products and produce cigarettes when the incense is burned. 16 Since this main ingredient is composed of organic matter, the incense usually volatilizes during the burning process. 20 In fact, many toxic organic compounds have been found in cigarettes, among which carbonyl compounds, volatile organic compounds (VOC) and polycyclic aromatic hydrocarbons (PAH) have been widely reported. Emissions of carbonyl compounds produced by burning ten different types of incense in a large environmental test chamber detected a total of eight carbonyl compounds, mainly aldehydes. It is worth noting that the concentration of the six types of formaldehyde is higher than the 8-hour average formaldehyde concentration recommended by Hong Kong IAQO (100 micrograms/m3), and the maximum combustion level of formaldehyde is even more than twice the standard value. 18 Similarly, the air samples collected from Hong Kong’s daily incense burning homes and temples also detected a large number of carbonyl compounds, in which formaldehyde is the most abundant carbonyl compound. In addition, the total mixing ratio of carbonyl compounds in the temple is 11-23 times higher than that outside the temple, and the concentration of formaldehyde in both places exceeds the WHO air quality guidelines. 38 Regarding VOC, their emissions from incense have also been measured and analyzed on the burning of different temples in China. It was found that 12 types of VOCs were identified in air samples, of which benzene, toluene and xylene were the species with the highest content exceeding the WHO recommended level of 0.05 mg/m3. 39 Gas-phase VOCs produced by the combustion of three types of fragrances, 14 to 17 VOCs were detected in cigarettes, of which benzene, followed by toluene, regardless of the type of fragrance, from the perspective of emission rate and emission factor, the emissions emitted during the incense process Major VOCs. 40 Recent data on emissions from burning nine types of incense products in a specific room in a laboratory dedicated to indoor air research have also observed very high concentrations of VOCs, including benzene and toluene. 41 In addition, a variety of polycyclic aromatic hydrocarbons may be found in naphthalene, acenaphthene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, pyrene and other cigarettes, benzo[a]anthracene, benzo[b]fluoranthene and benzene And [a] pyrene. It shows that the total average concentration of polycyclic aromatic hydrocarbons in the Arabic incense samples is 2.79 mg/m3, which is higher than the recommended level given by different environmental agencies. 42 In another study in Taiwan, the average concentration of polycyclic aromatic hydrocarbons in indoor air was 2.79 mg/m3. The temple is 6258 ng/m3, which is about 27 times that outside the temple and 11.6 times that of the city ruins. The measured value also reached nearly 80% of the concentration at the traffic source, indicating that the PAH concentration in the temple is very high. Although approximately 90% of the indoor airborne PAH detected in the temple is in the gas phase, the average particle-bound PAH concentration in the temple is twice and 1.2 times that of the outside and urban areas. 43 Consistently, other survey reports In the process of burning incense, a large amount of polycyclic aromatic hydrocarbons released into the environment. 44,45 Importantly, it has been observed that the PAH concentration in incense houses is higher than that in non-incense houses-burning houses have significantly higher indoor PAH concentrations than outdoor ones. 43 In general, cigarettes contain a variety of organic compounds in considerable concentrations. These compounds exist in the gas phase and can be absorbed by PM particles. Among these compounds, mixtures of formaldehyde, benzene, toluene and polycyclic aromatic hydrocarbons have attracted the attention of researchers not only because of their high content, but also because of their adverse effects on human health and the entire environment. It is worth noting that these compounds have been identified by IARC as human carcinogens. 46 In addition to carcinogenicity, short-term and long-term exposure to such toxic substances may cause a series of mild to severe adverse reactions, such as eye, nose, throat or skin irritation, anesthesia, neurotoxicity, aplastic anemia, cardiovascular disease , Respiratory system problems and kidney or liver damage. 47-49

In summary, the chemical substances produced by incense can be divided into two types: particle phase and gas phase, which are discharged at the same time. Due to changes in fragrance composition and experimental design, the reported characteristics of cigarettes still differ greatly, as shown in Table 1. Table 1 Summary of emission characteristics of incense

Table 1 Summary of emission characteristics of incense

Considering that cigarettes are a complex mixture of suspended particles and harmful gases, identifying the adverse effects of cigarettes on human health has attracted the attention of multidisciplinary scholars around the world. So far, the relationship between incense and a series of conditions has been proposed (Figure 1). However, the results of the investigation on this issue are still elusive and require further investigation. Figure 1 The possible adverse effects of cigarettes on human health. People who come into contact with incense may inhale a complex mixture of harmful chemicals, which can cause diseases ranging from irritation to cancer. The potential effects of burning incense have been observed in many vital organs.

Figure 1 The possible adverse effects of cigarettes on human health. People who come into contact with incense may inhale a complex mixture of harmful chemicals, which can cause diseases ranging from irritation to cancer. The potential effects of burning incense have been observed in many vital organs.

Because cigarettes contain a variety of irritants, they may cause a variety of irritation reactions, including allergic reactions, in many parts of the body (such as the eyes, nose, throat, or skin). In fact, a series of clinical case reports indicate that incense can cause allergic contact dermatitis in various parts of the human body. For example, a 63-year-old man has itchy discoloration patches on the back of his left hand, left shoulder and abdomen. He has practiced incense burning for about 15 years and determined that the perfume in the incense is the culprit. 50 Another case is that a woman who burned incense every day for about 5 years suffered from air-borne pigmented contact dermatitis due to the musk in the incense. 51 On the other hand, a cross-sectional survey was conducted on the prevalence of acute irritation in a group of temples. The workers in Kaohsiung, Taiwan are compared with a group of church workers. The results showed that a series of acute adverse symptoms such as eye irritation, nasal secretions, dryness or congestion, throat irritation or dryness, and nausea were significantly higher among temple workers than church workers. In addition, as observed in models that control for potential confounding factors, working in temples seems to increase the chances of throat irritation and nose irritation by 45% and 41.4%, respectively, compared with working in churches, indicating that occupational exposure is associated with 52 Similarly, in another population-based cross-sectional study, the subjects were 36,541 adults from 6 large cities in China. Burning or irritation), throat (hoarse or dry throat) and skin (dry or flushing of the facial skin, scaly/pruritus on the scalp or ears, skin symptoms). Hands, such as dry, itchy or red skin). 53 Importantly, according to the Taiwan birth cohort, burning incense regularly is the most critical risk factor for health problems in housing characteristics. Atus for children 3 to 5 years old, regardless of whether the parents have a history of allergies and respiratory diseases. In particular, it was found that frequent burning of incense was associated with diagnosed childhood asthma and allergies, and the level of significance was doubled in the presence of paternal inheritance. 54 In summary, the current literature supports clues about the association between exposure to incense and allergies. Development of irritation and/or allergy symptoms.

As we all know, no matter the source, inhaled smoke can have harmful effects on the respiratory system. Therefore, when the incense burns, the emitted smoke is likely to be inhaled into the body, which may cause breathing problems. In fact, a number of epidemiological studies have shown that incense has an effect on the respiratory system. However, the results are still elusive. In a prospective cohort study of more than 4000 school children in Hong Kong from 2012 to 2014, it proved the adverse effects of incense on children's lung function and lung function development. In addition, exposure to household incense was found to be associated with an increased risk of bronchitis and bronchiolitis in men and women, as well as pneumonia and wheezing, but only in boys. The reason for this gender sensitivity is unclear. A reasonable explanation is that at baseline, respiratory problems in boys are more common than those in girls. 55 Consistently, previous cross-sectional population studies of children have also shown that incense is associated with increased risk of various respiratory diseases and symptoms, such as 56-58. On the other hand, the opposite finding is that incense is related to the prevalence of respiratory diseases. There was no significant relationship between them, including chronic cough, chronic sputum, chronic cross-sectional survey of 346 Hong Kong primary school students reported bronchitis, runny nose, wheezing, asthma, allergic rhinitis or pneumonia. 59 The lack of this association may be due to several reasons. First, the concentration and duration of personal exposure to household incense may be relatively low. Secondly, the competitive effect of other air pollutants may ignore the impact of cigarettes on the respiratory system. Finally, the high incidence of respiratory diseases in reality and their etiology may conceal the impact of cigarettes. Similarly, the association between adolescent and adult exposure to incense and breathing problems has also been documented, but the results are inconsistent. According to data from the Taiwan Youth Asthma Screening Project, more than 5,000 students aged 14-16 years were recruited, and about 71% of them may be exposed to incense at home. Approximately 10% of the participating students were randomly selected for pulmonary function tests. Through multivariate linear regression analysis controlling for potential confounding factors, compared with students living in families without incense burning, the lung function of students who were exposed to family burning incense every day was significantly reduced. In addition, there was no significant association between impaired lung function and burning incense twice a month. 12 In addition, a cross-sectional health survey of 109 temple workers (as the exposure group) and 118 church workers (as the control group) of Kao-Taiwan Hsiung showed that temple workers are more common in coughing and sputum than church workers , Wheezing or breathing difficulties and other chronic respiratory symptoms. In particular, the incidence of cough, phlegm, and dyspnea was significantly higher in the exposed group. It is worth noting that after controlling for potential confounding factors, the cough symptoms of temple staff are still significantly more common, which indicates that exposure to cigarettes may increase the risk of respiratory symptoms. 52 In contrast, there is no significant association between burning incense and increased respiratory problems. 59 In addition, a cohort study in Taiwan showed that chronic obstructive pulmonary disease (COPD) is an incurable disease characterized by chronic airflow. Short-term exposure to incense may not affect its lung function and respiratory symptoms. 60 Similarly, the previous case-control study conducted in Saudi Arabia did not find that the use of incense burners was a risk factor for COPD. 61 However, the small sample size and non-longitudinal study design may have affected the results and may not be generalized to the COPD population. Experimentally, evidence obtained from animal studies shows that incense is related to unfavorable ultrastructural changes in the lungs. 62,63 For example, rats exposed to an Arabic incense at a rate of 4 g/day in the exposure chamber for 14 weeks showed obvious ultrastructure. Changes in alveolar lung cells of exposed animals compared to unexposed controls. These changes include alveolar cell proliferation and subsequent alveolar septal cell increase, neutrophil infiltration in the alveolar cavity, degenerative and necrotic changes in the alveolar lining cells, red blood cell extravasation in the expanded alveolar capillaries, and collagen fiber deposition and Subsequent wall thickness. , Existing evidence suggests that there is a potential link between exposure to incense and the development of various respiratory problems. However, due to differences in the concentration, frequency, and duration of exposure between different groups of people, the results of the study are still inconsistent and require further investigation.

A large number of epidemiological and biomedical studies have shown that cigarettes have the ability to induce various cardiovascular diseases. Importantly, it is reported that there is a close relationship between incense and death from cardiovascular disease (CVD). 13 A cross-sectional study of 132 Thai and Vietnamese adults over 35 years old in Thailand showed that there is a positive correlation between family incense and carotid arteries. Multivariate regression analysis of the arterial intima-media thickness (CIMT) after controlling for potential confounding factors. 64 Since CIMT usually determines the level of atherosclerosis and thus estimates the risk of CVD, 65 these findings suggest that burning incense at home may be a risk factor. The development of cardiovascular disease. In addition, through an analysis of 50 housewives from 50 households in downtown Taipei, it was found that 48% of households had burnt incense, and burning incense would increase indoor PM2.5 levels, thereby changing the relationship between the two. Family PM2.5 and heart rate variability index. 66 This effect modification may also link incense to an increased risk of CVD. It is worth noting that in a large group of middle-aged and elderly people in Singapore, it has been found that burning incense daily at home for more than 20 years is associated with an increased risk of cardiovascular death. In particular, compared with people who have used incense before and who have never used incense, people who currently use incense may increase the risk of cardiovascular death by 12%, with the risk of coronary heart disease and stroke increasing by 10% and 19%, respectively. In addition, in the study population, up to 7% of coronary heart disease deaths and 12% of stroke deaths can be attributed to long-term use of incense. 13 Although the study still has some limitations, such cohort surveys provide strong evidence of causality. In this relationship, cigarette exposure precedes cardiovascular mortality as a health outcome. Consistent with epidemiological investigations, an experimental study of rats found that exposure to cigarettes was associated with adverse metabolic changes associated with increased triglycerides over time and decreased high-density lipoprotein cholesterol concentrations. 67 Another animal experiment also observed that rats exposed to cigarettes showed significant ultrastructural changes in myocardial tissue, cardiac hypertrophy associated with increased expression of hypertrophic genes, and depletion of creatine kinase-myocardial binding enzyme and lactate. Myocardial tissue damage is characterized by a significant increase in hydrogenase. 68 The endothelial function was studied through the blood flow-mediated expansion of pigs, and significant impairment of the flow-mediated expansion was observed after 30 minutes of exposure to cigarettes. Interestingly, this damage is closely related to the CO level in the exposure chamber, but not to total particulate matter and venous CO-hemoglobin, which means that the vapor phase of the cigarette accompanied by CO rather than the CO itself is an acute endothelial dysfunction after exposure to cigarettes 69 Similarly, the relationship between endothelial dysfunction and temple particles is demonstrated by the following findings: exposure of human coronary artery endothelial cells to particles collected in major temples in China leads to a significant increase in endothelin-1 and a decrease in nitric oxide synthesis. 70 While the underlying mechanism is not yet clear, these experimental evidence supports concerns about the increased risk of cardiovascular disease in individuals exposed to cigarettes. On the other hand, as the main risk factor for cardiovascular disease, the relationship between incense and hypertension has been studied. According to the data from the Chinese cross-sectional survey, a population study was conducted and it was observed that there is a significant correlation between the frequency of incense burning and the risk of hypertension and increased blood pressure, and there is a clear exposure-response relationship. Subsequent gender-specific analysis showed that women have a greater influence than men. 71 This may be because Chinese women spend more time at home than men and participate in more ritual activities, which leads to a higher personal exposure to cigarettes. Similarly, a large Chinese birth cohort study also confirmed the association between frequent family incense exposure and higher risk of hypertension and higher blood pressure levels, but it was also confirmed in the pregnant population. 72 In general, burning incense should be regarded as a risk factor. For various adverse cardiovascular outcomes and related diseases, frequency and duration may be important determinants.

Some current evidence suggests that there is a reasonable connection between incense and several neuropsychological diseases. In a 3-year prospective longitudinal case-control study of 515 adults over 65 years of age without stroke and dementia in Hong Kong, compared with non-smokers, smokers had poorer cognitive and brain abilities. Reduced connectivity is related. In addition, significant interactions between indoor incense and diabetes, hyperlipidemia, and white matter hyperintensity have been observed. In the presence of vascular risk factors, incense can cause cognitive decline. 73 It is worth noting that exposure to incense during pregnancy may have profound effects on the nervous system. In future generations. According to a Chinese cohort study involving nearly 43,000 participants, it was calculated that prenatal exposure to incense was significantly positively correlated with preschool children’s early-onset hyperactivity behavior. 74 Similarly, using the national data set of the Taiwan Birth Cohort Study, delays have always found exercise milestones in infants born in incense-burning families. It is worth noting that this association is more pronounced in mother-infant pairs under the continuous exposure category, indicating that there may be a dose-response effect. 75 Also based on the Taiwan birth cohort study, there is a negative correlation between burning incense before childbirth and the outcome of infant birth as measured by birth weight. In another survey, head circumference was determined. In particular, studies have found that incense is associated with lower birth weight in boys, but not in girls, and the same is true for smaller head circumferences. 76 Poor health of babies at birth has been shown to be associated with a higher risk of neurodevelopmental abnormalities. 77,78 Therefore, despite the few published data, the potential adverse effects of personal and mother exposure to incense on neuropsychological development and function should not be overlooked.

Experiments have shown that in early in vitro studies, through different analyses, cigarettes have been proven to have mutagenicity and/or genotoxicity, 79-81 may lead to the production of DNA adducts, which is a key step in the carcinogenic process. In fact, incense will release a large number of toxic substances, many of which have been confirmed or suspected to be human carcinogens, especially carcinogens related to lung cancer. So far, the relationship between burning incense and lung cancer is still a controversial issue. One of the earliest evidence of a positive correlation is a hospital-based case-control study conducted in Singapore in the 1970s, in which a univariate analysis reported that there was a strong correlation between lung cancer and the use of incense while sleeping, and the overall relative risk was 4.11 ( p <0.01). 82 The lack of adjustment for potential confounding factors such as age, gender, and smoking status is the main shortcoming of this study. After adjusting for the demographic variables of smoking and confounding, another hospital-based case-control survey of 331 lung cancer cases and 331 matched controls in Hong Kong showed that exposure to incense during the holiday season significantly increased the risk of lung cancer in women Relevant (adjusted odds ratio (OR) = 2.95; 95% confidence interval (CI): 1.10–7.87) but not daily exposure (adjusted OR = 1.58; 95% CI: 0.77–3.26). At the same time, neither daily exposure (adjusted OR = 0.94; 95% CI: 0.56–1.56) and holidays (adjusted OR = 1.03; 95% CI: 0.47–2.26) did not appear to be associated with an increased risk of lung cancer in men. 83 The stronger associations found in women may be due to their higher propensity to use incense. However, in a Chinese population case reference study of 1208 male lung cancer cases and 1069 matched reference subjects, unconditional multivariate logistic regression analysis showed that men exposed to frequent incense burning significantly increased the risk of lung cancer in the entire population . (≥ 2 times/day; OR = 1.26; 95% CI: 1.01–1.58) or those who have experienced high-accumulation incense exposure (≥ 60 days/year; OR = 1.38; 95% CI: 1.10–1.75) The comparison has never been done after adjusting for potential confounding factors. In addition, the synergy index of smoking and frequent use of incense or smoking and high cumulative use all indicate that the combined effect of these exposures on lung cancer risk is twice that of the expected additive effect, indicating that the association between incense and lung cancer is more Obviously among male smokers. 14 There is a similar interaction between smoking and exposure to incense or mosquito coils (p = 0.016). In particular, the ORs of smokers who use and do not use incense or mosquito coils per day are 4.61 and 2.80, respectively. 84 Nevertheless, it may be misleading to use incense and mosquito coils daily as an exposure of interest rather than a combination of single incense exposure. Judge the connection between the two. Incense and lung cancer risk. On the other hand, zero correlation between incense and lung cancer is also recorded. A prospective cohort study based on the Singapore Chinese population could not observe the overall effect of incense on the development of lung cancer regardless of smoking status. It is also frequently investigated, and most of the available evidence is related to nasopharyngeal carcinoma (NPC). A Hong Kong Chinese case-control study of 352 NPC cases and 410 controls observed that women who burn incense at home every day have an increased risk of NPC (adjusted OR = 2.49; 95% CI: 1.33-1.46), but in men (Adjusted OR = 0.96; 95% CI: 0.63–1.45). It is worth noting that a significant exposure-response relationship has been found, in which women who burn incense at home for 40 years or more are at more than four times the risk of developing nasopharyngeal cancer than non-users. 85 Similarly, China's large-scale case control study of 1845 cases and 2275 controls also reported a positive correlation between incense and the risk of NPC. After adjusting for potential confounding factors, the risk of nasopharyngeal cancer for people who regularly smoked incense was about 73% higher than those who never burned incense. 86 In contrast, a prospective cohort study of Chinese Singaporeans could not observe an association between current incense use and increased smoking. The risk of NPC. Instead, it was found that the use of incense was dose-dependently associated with an increased risk of non-nasopharyngeal upper respiratory tract cancer. 15 In addition to respiratory cancer, the relationship between incense and other malignant tumors (such as leukemia and brain tumors) has also been confirmed. Report. A case-control study of children aged 10 and under in Los Angeles County found that children whose parents burn incense at home more than once a week during pregnancy or breastfeeding have a significantly increased risk of leukemia (OR = 2.7; 95% CI: 1.18–7.14; p = 0.007), after adjusting for confounding variables, such as parental occupational exposure, parental use of garden sprays, or parental use of household pesticides. 87 On the other hand, in addition to nitrosamines and other N-nitroso compounds as a source, burning incense has been hypothesized to be a risk factor for brain tumors since the early 1980s. A case-control study of 209 young brain tumor patients and 209 controls observed a significant association between the mother’s exposure to incense during the first pregnancy and the increased risk of brain tumors (OR = 3.3; p = 0.005). 88 In contrast, this association was not found in other case-control investigations. 89,90 Although the two subsequent studies did not confirm the previous findings, the frequency of the incense-burning mothers was equal to or slightly higher than that of the control mothers. In general, there may be an association between personal or pregnancy exposure to incense and increased cancer risk, although there is still controversy. This conflicting finding may be due to differences in reference selection, confounding control, and sample size. Therefore, it is very necessary to carry out a larger forward-looking cohort in the future, and carry out appropriate reference selection and appropriate analysis and adjustment.

Scattered evidence on other adverse effects of incense on human health has been recorded. In a case report, a 65-year-old female housewife who smoked a large amount of incense daily and was exposed to a large amount of smoke for more than 30 years developed dizziness, fatigue, severe anemia, pitting edema of the calf, sore limbs, abdominal pain and exertional breathing difficulty. It is worth noting that the blood lead levels of the patient and all family members are as high as lead poisoning. 91 In addition, a large-scale cross-sectional survey of preschool children in Taiwan found that household burning incense is an important factor in the increase of blood lead levels (p <0.0003), and a dose-dependent relationship with the frequency of incense burning was established (p = 0.0022) ). 92 These preliminary results indicate that households with incense burning habits are at greater risk of exposure to lead. On the other hand, a recent population-based prospective cohort of middle-aged and elderly Singaporean Chinese found that after adjusting for potential confounding factors, compared with non-users, people who currently use incense have a 23% higher risk of end-stage renal disease. In the case of burning incense every day for more than 20 years, this risk further increases. 19 Consistently, the adverse effects of long-term exposure to cigarettes on kidney function and structure have been observed in previous experimental studies. In particular, exposed rats showed significant persistent inflammation as well as abnormal function and ultrastructural changes of the kidneys. 93 The current limited information may send some signals to researchers asking them to take further measures in order to establish a more comprehensive picture of all possible hazards. Burn incense.

Redox (redox) homeostasis is vital to life, because the redox process involves all the basic processes from bioenergetics to metabolism to other functions. 94 The global concept of oxidative stress is "the imbalance between oxidants and antioxidants favors oxidants, leading to the destruction of redox signals and control and/or molecular damage." 95 The field of oxidative stress research has aroused the interest of the world scientific community, because oxidative stress may make outstanding contributions to human diseases. 96 Although the underlying mechanism of the effects associated with incense burning in the context of unhealthy conditions is unclear, there are several pieces of evidence supporting the role of oxidative stress as a possible mediator. This section aims to analyze the existing evidence that may shed light on this issue. All in all, the health outcomes associated with burning incense are thought to be driven by oxidative stress, which in turn can lead to abnormal inflammation and irreversible DNA damage (Figure 2). However, there are still many gaps, so further research is needed to provide a deeper understanding. Figure 2 The possible oxidative stress mechanism supporting the health effects of burning incense. After entering the body, the components of cigarettes can enhance the production of ROS in some ways, leading to oxidative stress and related consequences. Oxidative DNA damage and improper DNA repair may cause cancer. In addition, oxidative stress and inflammation may be related to each other, leading to the pathogenesis of heart and lung diseases. Abbreviations: COX-2, cyclooxygenase-2; CYPs, cytochrome P450 enzymes; ET-1, endothelin-1; IL-6, interleukin-6; IL-8, interleukin-8; NADPH oxidase , Nicotinamide adenine dinucleotide phosphate oxidase; NO, nitric oxide; PAHs: polycyclic aromatic hydrocarbons; PM, particulate matter; ROS, reactive oxygen species.

Figure 2 The possible oxidative stress mechanism supporting the health effects of incense. After entering the body, the components of cigarettes can enhance the production of ROS in some ways, leading to oxidative stress and related consequences. Oxidative DNA damage and improper DNA repair may cause cancer. In addition, oxidative stress and inflammation may be related to each other, leading to the pathogenesis of heart and lung diseases.

Abbreviations: COX-2, cyclooxygenase-2; CYPs, cytochrome P450 enzymes; ET-1, endothelin-1; IL-6, interleukin-6; IL-8, interleukin-8; NADPH oxidase , Nicotinamide adenine dinucleotide phosphate oxidase; NO, nitric oxide; PAHs: polycyclic aromatic hydrocarbons; PM, particulate matter; ROS, reactive oxygen species.

Reactive oxygen species (ROS) refers to a group of molecular oxygen derivatives produced by redox reactions or electronic excitation. 97 The continuous intermediate step of oxygen reduction is the formation of superoxide anion radicals, hydrogen peroxide and hydroxyl radicals, which represent three important active oxygen species. In addition, ground state molecular oxygen can be excited into singlet molecular oxygen by electrons. 98 A large amount of information indicates the importance of ROS as a functional signaling entity to physiology. 97 Contrary to physiological levels, high concentrations of ROS can cause damage to cell macromolecules and other cellular consequences, leading to oxidative stress and related pathological conditions. 96 It is now clear that the production of ROS comes from endogenous and exogenous sources. The former source usually includes mitochondria, peroxisomes, endoplasmic reticulum, and NADPH oxidase complex, while the latter may be the result of cumulative environmental exposure, such as smoking, air pollution, chemicals, exogenous substances, and radiation. 99 Recently, micro and nano soot particles, also known as ROS generation platforms, 100,101 mainly exist in cigarettes. Compared with diesel engine exhaust particles and carbon black, these particles can show strong oxidizing ability, produce higher ROS and greater oxidative DNA damage. 102 In addition, it is reported that incense particles can alter mitochondrial function and NADPH oxidase activity, leading to the second wave of ROS production. 102 In addition, through a number of investigations, a wide range of oxygen-containing compounds have been identified throughout cigarettes, including polar organic compounds, highly reactive carbonyl compounds, redox cycle quinones, and transient metals. 102-104 These compounds 105-107 In fact, it is reported that incense will trigger phase I metabolizing enzymes of xenobiotics, such as the cytochrome P450 (CYP) system, which catalyzes the production of reactive polycyclic aromatic hydrocarbons and other chemical substances. Metabolites. 68,108,109 may come from mixed sources, including (1) incense particles and other oxygenates, (2) mitochondria and NADPH oxidase dysfunction, and (3) CYP induction. Therefore, incense is a potential favorable condition for the overproduction of ROS, and ROS may mediate the progression of human diseases through oxidative stress.

The other side of redox balance is cellular defense, which balances harmful levels of oxidants through enzymatic and non-enzymatic antioxidants, forming an antioxidant network on three basic levels of prevention, interception and repair. 97,110 The first-line antioxidant defense usually includes three key enzymes: superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), their role is to inhibit or prevent active substances The production. 111 The second line is usually referred to as a scavenger that neutralizes or scavenges free radicals. Among them, γ-L-glutamyl-L-cysteyl-glycine, or glutathione (GSH), is of great significance. 111,112 The third line is a group of enzymes that can repair the damage caused by oxidants and protect the body from its harmful effects. 111 In this case, oxidative stress can be considered a cellular state, which is an over-produced oxidant Overwhelming the level of antioxidant defenses that can work together. 113 So far, there have been three different kinds of evidence showing the ability of cigarettes to induce oxidative stress in vitro and in vivo, as described in Table 2. First, it is reported that the fragrant particles can be dosed-114. Secondly, a significant reduction in the level of antioxidants, including SOD, CAT and GSH, was observed in rats exposed to cigarettes. 68,93,109,115 Third, the level of malondialdehyde (MDA), which is a biomarker widely used in the assessment of oxidative stress, 116 has a significant increase in the response to cigarettes in the body. 68,93,109,115 In addition, the expression of heme oxygenase 1 (HO-1) (an important marker of oxidative stress) was also studied by using a cell model to study incense smoke. 108 Although the findings from existing research help indicate the oxidative stress caused by exposure to incense, it is still difficult to extrapolate to humans. Therefore, research on the human body and analysis of antioxidant activity/capacity and/or oxidative stress markers may provide insights into the actual ability of cigarettes to induce oxidative stress at exposure concentrations. Table 2 Summary of evidence on the ability of incense to induce oxidative stress

Table 2 Summary of evidence on the ability of incense to induce oxidative stress

As we all know, oxidative stress can cause damage to important molecules such as proteins, lipids and nucleic acids. 96 It is reported in the literature that DNA may be one of the key targets of ROS induced by incense, causing oxidative damage to DNA and even hindering subsequent transcription, replication and repair processes. 117 In fact, it was found that the level of biomarkers of DNA oxidative damage in temple workers increased twice, namely 8-oxo-2ʹ-deoxyguanosine (8-OHdG). 118 Similarly, oxidative DNA damage in human alveolar epithelial A549 cells is also It is caused by exposure to PM produced by incense burning and is characterized by the level of 8-OHdG. 117 In response to the consequential damage to DNA, organisms are equipped with tools to remove or tolerate DNA damage, called DNA repair mechanisms/pathways. 119 Unfortunately, a significant reduction in DNA repair capacity has been observed118 These preliminary data indicate that exposure to incense may cause an oxidizing environment that threatens DNA stability. Importantly, manifestations of oxidative DNA damage and insufficient DNA repair may be signs of carcinogenesis and other pathologies. 120,121

Air pollution refers to a heterogeneous mixture of gases (for example, carbon oxides, nitrogen oxides, and sulfur dioxide), particulate matter, and organic volatiles. 122 Oxidative stress is one of the pathophysiological mechanisms of animal models and human exposure to air pollution. 123 Considering that air pollution enters the body mainly through inhalation, the initial parts of oxidative stress are usually the airways and lungs, which is called pulmonary oxidative stress, which then triggers lung inflammation and promotes lung damage. 124 In fact, there is too much evidence linking pulmonary oxidative stress caused by air pollution to the adverse consequences of the respiratory system. 122,125 Since the burning of incense usually produces smoke composed of components similar to air pollution, the paradigm of pulmonary oxidative stress may be a reasonable basis for cigarette-mediated toxicity. In fact, several exposure studies using different models have shown that increased oxidative stress in the lung compartment can further trigger inflammation and regulate downstream signaling pathways. According to reports, exposure to incense particles can induce oxidative stress, change cell cycle regulation and cytoskeleton assembly, and lead to human alveolar epithelial A549 cell apoptosis and cell dysfunction. 114 Incense has also been shown to trigger the expression of cytokines and chemokines. Respiratory epithelial cells cause damage to the respiratory system. Interestingly, up-regulation of inflammatory molecules and significant changes in oxidative stress markers have been reported. 108,109 Inflammation markers, including interleukin 8 (IL-8) and cyclooxygenase 2 (COX-2), were exposed to PM extracts from different types of incense in macrophage models and lung-derived cell lines. Correspondingly, the genes encoding these molecules were also up-regulated108. Pathogenesis of airway inflammation. 127 Similarly, it was found that the emission of Arabic incense induces an inflammatory response in human epithelial A549 cells, as shown by a significant increase in the relative expression level of IL-8.11. Lung tissue was also observed in rats exposed to cigarettes. 109 Neutrophils are involved in the pathogenesis of asthma and lung diseases, 126 and it has been found that Arabic incense exposure induces neutrophil infiltration in the alveoli of rats. 63 Overall, the downside is that the effects of cigarettes on the respiratory system seem to be driven by the induction of oxidative stress in the lungs. Obviously, the mechanism of pulmonary oxidative stress inducing inflammation and mediating downstream signaling pathways is not yet fully understood, and further research is needed. In addition, in humans, the response is complex and depends on many variables, such as concentration, duration, deposition, distribution, isolation, and host susceptibility. 128 By using the International Commission on Radiological Protection (ICRP) model, the deposition measured metal particles in the human respiratory tract from temples burning incense. It is observed that the total deposition flux ranges from 83% to 84.82% of the total concentration of atmospheric metals, with the highest rate found in the respiratory tract of the head. 100 Similarly, the personal exposure dose rate due to incense burning in the human respiratory tract is calculated using the time-activity and particle size distribution data collected from traditional houses in Taiwan using the modified ICRP model. It was found that the deeper lung area had a lower average particle mass lung/indoor ratio; meanwhile, the average comprehensive deposition dose rate was highest in the extrathoracic area, followed by the bronchioles and bronchus areas. Importantly, the main deposition mechanism is proposed by the inertial impact rate. Through the inertial impact rate, the deposition rate increases as the particle size increases and the airway diameter decreases. 101 The development of mechanical dosimetry models is very necessary to discover the relationship between deposition patterns and exposure-dose-response, so as to provide a reliable tool for health risk assessment.

Vascular endothelium is an indispensable barrier. It regulates multiple exposures and prevents vascular inflammation and damage through multiple paradigms. The production of nitric oxide (NO) is the main pathway. 123 In the vasculature, ROS comes from multiple sources, such as mitochondria, NADPH oxidase, xanthine oxidase, and uncoupled endothelial nitric oxide synthase. Fortunately, antioxidant defenses can prevent the vascular system from the harmful effects of ROS. However, cardiovascular risk factors may increase the production of ROS, and if it exceeds the counteracting ability of the antioxidant system, it will lead to oxidative stress. 129 The main ROS produced in response to stimulation is superoxide anion, which quickly combines with NO to produce peroxynitrite, which reduces the bioavailability of NO and 130. In this case, vascular oxidative stress may precede many cardiovascular diseases. Endothelial dysfunction plays a key role in the occurrence and development. In addition, the dysregulation of NO release may represent an important link between risk factors and cardiovascular disease. It was found that the granular extracts exposed to Taiwanese temples can significantly increase the production of interleukin 6 (IL-6) and endothelin-1 (ET-1), and significantly reduce the synthesis of NO in the human coronary artery endothelial cell model. 70 Similar significant increases in ET-1 and reduction in NO were also observed in vascular tissues obtained from a rat model, which were exposed to smoke from incense burning. 115 The pro-inflammatory molecule IL-6 has been fully proven to play a central role in the pathophysiology of cardiovascular diseases. 131 and ET-1 is a vasoconstrictor secreted by endothelial cells and a natural antagonist of NO.132. Endothelial dysfunction may be caused by an increase in ET-1 and/or a decrease in NO, which ultimately leads to vascular morbidity and mortality. 132 indicates that whole body exposure to the smoke produced by incense may cause oxidative stress in the heart tissue of rats, which is determined by a significant increase in o levels, f oxidative stress markers and a significant decrease in antioxidant levels. In addition, compared with the unexposed control group, a significant increase in the levels of various chemokines and inflammatory mediators was detected in the heart tissue of the rats exposed to cigarettes, indicating that the direct immune response to cigarettes or indirect regulation, The infiltration of inflammatory mediators in the heart tissue increases through oxidative stress. The authors proposed that the increased expression of CYP1A1 and CYP1A2 genes may contribute to incense-induced oxidative stress and inflammation. 68 All these evidences indicate that vascular oxidative stress and inflammation are direct sequelae of exposure to incense burning. Obviously, many gaps still exist. First of all, it is not clear how the ingredients in cigarettes may enter the bloodstream and affect the vasculature. Secondly, there is still little in-depth information on the regulation and expression of oxidant sources and antioxidant defenses in exposure models. Third, the potential signaling pathways of cigarettes on vascular oxidative stress and cardiovascular effects have not been fully studied.

Early observations showed that systemic exposure to incense can trigger systemic oxidative stress and enhance systemic inflammation in rats. Interestingly, stopping contact will result in a significant reversal of the detected markers. 115 This finding underscores the possibility that poor health outcomes after exposure to incense burning may be due to systemic oxidative stress. Although the involvement of oxidative stress in lung and vascular compartments has gradually been documented in the literature, the role of this cell state in mediating the systemic effects caused by exposure to incense remains to be elucidated.

The adverse effects of incense on human health may have some important public health effects. To curb the growing threat posed by this common practice requires multifaceted efforts at all levels.

There is no doubt that no individual or organization can violate religious and spiritual freedom. A good approach should be cooperation between the government and stakeholders (such as religious leaders and the media) to disseminate knowledge about the potential impact of incense to users, thereby raising awareness of this risk. Another option is that the government can impose a tax on incense to reduce the amount of incense used. However, in this case, smuggled products made of cheap and unfriendly materials may flood the incense market. Instead, the situation can be improved by developing safer incense practice guidelines. For example, it is reported that emissions and health risks may vary depending on housing conditions, especially ventilation. 17,133,134 Therefore, when incense burning cannot be avoided, every effort must be made to improve indoor air quality, such as reducing incense burning, expanding space, promoting ventilation, and choosing healthy fragrances.

Since it is relatively impractical to prevent the use of incense, the development of alternatives with lower health risks is a potential approach. Under the same combustion conditions, there is a positive correlation between the total metal content and the combustion speed, and there is a negative correlation between the total metal content and the particulate matter emissions. 135 These results show that the higher the metal content in the incense, the more effective it is to promote combustion and reduce harmful particulate emissions. In fact, it is calculated that when the total metal content is increased from 0.5% to 2%, particulate matter emissions can be reduced by up to 40%. 135 Therefore, incense manufacturers can optimize the quantity and quality of raw materials, such as total metal, to make safer products. In addition to traditional incense, alternative electronic solutions can also be introduced and adopted as a risk reduction action. At present, electronic fragrance products are mainly divided into three categories, including 1) visual appearance simulation of traditional incense, but no fire, smoke, incense; 2) visual and fragrance simulation, but no smoke; 3) healthy and friendly simulated visual appearance and burning The smoke and aroma are emitted. 1 Through the application of electronic simulation incense, users can still experience similar religious practices and build a bridge between spiritual life and physical health. However, religious beliefs may be the main reason why incense users are reluctant to use these alternative products. 1 Interestingly, in the current 4.0 era, virtual incense through mobile applications may be expected to become a promising alternative. Obviously, exploring effective alternative solutions to promote healthy and friendly incense practice is a long and challenging journey.

Since oxidative stress is considered to be the main mechanism for incense to adversely affect biological systems, antioxidants can be used as adjuvants to reduce this risk. The clinical significance of oxidative stress and antioxidant-based strategies in many types of diseases has been documented. 136-138 Although the effectiveness of antioxidants in reducing the adverse effects associated with burning incense is still lacking empirical findings, there is an association between the health risks of a healthy diet and the recommended use of incense. A cross-sectional survey in Hong Kong found that after adjustment for confounding factors, incense had no significant effect on the risk of lung cancer among non-smokers, and even significantly reduced the risk of lung cancer among smokers. This unexpected finding was attributed to information about the use of incense and eating habits of more fresh fish, more retinol, and less alcohol. 59 Similarly, earlier epidemiological studies conducted among Chinese women in Hong Kong gave the same observations, which were explained by a relatively better diet by consuming more fresh fruits, vegetables, and fish. 139 These preliminary data should provide an idea for further investigation to explore the effectiveness of antioxidants in hindering the health risks associated with incense burning, thereby providing a feasible method. And effective methods.

As a part of human culture and religion, incense is found in many places around the world, especially in Asia. However, since the 1990s, people have noticed that the use of incense poses a potential risk to human well-being, because a study has shown that certain cigarette condensates are more genotoxic than the genotoxicity of tobacco smoke in mammalian cells . 81 In addition, early experiments found that the emission rate of particulate matter per gram of incense burning is twice that of cigarettes,140 and the aerosol produced by incense burning is similar to the aerosol condensed in environmental tobacco smoke. 141 Considering the popularity of incense around the world, these preliminary data may cause people to worry about the threat of incense to human health in addition to smoking and air pollution. Many evidences now show that burning incense may affect all stages of life, from before conception to old age, and has multiple effects on health. A lot of work has been done to explore the toxicity status of incense related to human health. Although the underlying mechanism is still in the early stages of research, oxidative stress and related inflammatory responses seem to be the reasonable pathophysiological pathways behind the adverse effects of cigarettes. It is worth noting that smoking is also recognized as an oxidative stressor, which induces the accumulation of reactive oxygen species, which in turn causes damage to the body. 142 Since both cigarettes and tobacco smoke may affect biological systems through the same way, it is not surprising that cigarettes have different effects on former or current smokers than never smokers, but in different ways. For example, the literature documents a more pronounced association between the use of incense in male smokers and lung cancer. 14 In contrast, among smokers who have been exposed to the potent harmful substances of smoking, it was observed that incense burning had a smaller effect on kidney function compared to non-smokers. 19 In addition to incense, incense ash, as a product of the combustion process, also has health problems and requires more understanding. Summarizing all the potential effects of incense on human health and the environment, further investigations are necessary in the future. The more evaluations of fragrance products, the better the measures to reduce their consequences. Obviously, this is a problem that requires multidisciplinary efforts.

We thank Dr. Lin Weining for the discussion and comments.

This work was supported by Taipei Medical University Hospital, grant number 110TMU-TMUH-14, Chang Gung Memorial Medical Research Foundation, grant number CMRP6J0051 and Chang Gung University of Technology, grant number ZRRPF3L0091 and ZRRPF3K0111.

The author declares that there is no conflict of interest in this work.

1. Qin Z, Song Y, Jin Y. Green worship: the influence of belief and behavior factors on the use of electronic incense products in religious activities. Int J Environ Res Public Health. 2019;16(19):3618. doi:10.3390/ijerph16193618

2. Jetter JJ, Guo Z, McBrian JA, Flynn MR. Characterization of incense emission. The total environment of science. 2002;295(1–3):51–67. doi:10.1016/s0048-9697(02)00043-8

3. Yadav VK, Kumar P, Kalasariya H, etc. The status quo of the Indian incense sticks market and its impact on the Indian economy. Ind J Pure App Biosci. 2020; 8(3): 627–636. doi:10.18782/2582-2845.8168

4. Eggert T, Hansen OC. Survey No. 39 of Chemical Substances in Consumer Products. Danish Environment Agency. year 2004.

5. Yin H, Lin Q, You Z, Qiu J, Zhang E, Chen N. Research on an environmentally friendly fragrance composed of soybean-based adhesive and wood flour. Biological resources. 2019;14(3):5097-5108.

6. KHCEP Bureau. Reduce pollutants in the temple. See: Total Air Pollutant Control and Reduction Guidance Plan. Kaohsiung, Taiwan: KHCEP Bureau; 2003: 6-9.

7. Lin TC, Krishnaswamy G, Chi DS. Incense: its clinical, structural and molecular effects on airway diseases. Clinical Moore allergy. 2008;6:3. doi:10.1186/1476-7961-6-3

8. Apte K, Salvi S. Household air pollution and its health effects. F1000Res. 2016; 5: F1000 Teacher Revised Edition–2593. doi:10.12688/f1000research.7552.1

9. Yeatts KB, El-Sadig M, Leith D, etc. Indoor air pollutants and health in the United Arab Emirates. Environmental health perspective. 2012;120(5):687–694. doi:10.1289/ehp.1104090

10. Yadav VK, Gnanamoorthy G, Cabral-Pinto MMS, etc. As coal is burned in an open and controlled manner, the changes and similarities in structure, chemical and elemental properties of coal ash. Environ Sci Pollut Res Int. 2021;28(25):32609–32625. doi:10.1007/s11356-021-12989-5

11. Cohen R, Sexton KG, Yeatts KB. Hazard assessment of cigarettes in the United Arab Emirates (UAE). The total environment of science. 2013; 458-460: 176-186. doi:10.1016/j.scitotenv.2013.03.101

12. Chen YC, Ho WC, Yu YH. Adolescent lung function associated with burning incense at home and other environmental exposures. Indoor air. 2017;27(4):746–752. doi:10.1111/ina.12355

13. Pan A, Clark ML, Ang LW, Yu MC, Yuan JM, Koh WP. Incense Use and Cardiovascular Mortality among Chinese Singaporeans: A Study on Chinese Health in Singapore. Environmental health perspective. 2014;122(12):1279–1284. doi:10.1289/ehp.1307662

14. Tse LA, Yu IT, Qiu H, Au JS, Wang XR. Case reference study on lung cancer and incense, smoking and residential radon in Chinese men. Environmental health perspective. 2011;119(11):1641–1646. doi:10.1289/ehp.1002790

15. Fribourg JT, Yuan JM, Wang R, Koh WP, Lee HP, Yu MC. Incense and respiratory cancer: a prospective cohort study. cancer. 2008;113(7):1676–1684. doi:10.1002/cncr.23788

16. Yadav VK, Singh B, Choudhary N. Characterization of the physical, chemical and mineralogical properties of Indian incense powder. World J Environmental Biological Science. 2020; 9(1): 39–43.

17. Ji X, Le Bihan O, Ramalho O, et al. Characterize the particles emitted by burning incense in the laboratory room. Indoor air. 2010;20(2):147–158. doi:10.1111/j.1600-0668.2009.00634.x

18. Lee SC, Wang B. Air pollutant emission characteristics of incense burning in large environmental chambers. Atmospheric Environment. 2004;38(7):941–951. doi:10.1016/j.atmosenv.2003.11.002

19. Geng TT, Jafar TH, Yuan JM, Koh WP. Long-term use of incense by Singapore Chinese and the risk of end-stage renal disease: Singapore Chinese Health Research. BMC kidney. 2019;20(1):9. doi:10.1186/s12882-018-1186-9

20. Yadav VK, Yadav KK, Gnanamoorthy G, etc. Green synthesis and characterization of polyhedral-shaped amorphous iron oxide nanoparticles from the waste ash. Environmental technology innovation. 2020; 20:101089. doi:10.1016/j.eti.2020.101089

21. Kalender SS, Alkan GB. Air pollution. In: Hussein C editor. Environmental material management manual. Springer, Cham; 2019.

22. Jilla A, Kura B. Particulate matter and carbon monoxide emission factor from incense burning. Environmental pollution and climate change. 2017;1(4):140. doi:10.4172/2573-458X.1000140

23. Penney D, Benignus V, Kephalopoulos S, Dimitrios K, Michael K, Agnes V. Carbon monoxide. In: WHO indoor air quality guidelines: selected pollutants. Geneva: World Health Organization; 2010. Available from https://www.ncbi.nlm.nih.gov/books/NBK138710/. Visited on June 31, 2021.

24. Rose JJ, Wang L, Xu Q, et al. Carbon monoxide poisoning: pathogenesis, management and future treatment directions. Am J Respir Crit Care Med. 2017;195(5):596-606. doi:10.1164/rccm.201606-1275CI

25. Jarvis DJ, Adamkiewicz G, Heroux ME, Rapp R, Kelly FJ. Nitrogen dioxide. In: WHO indoor air quality guidelines: selected pollutants. Geneva: World Health Organization; 2010. Available from https://www.ncbi.nlm.nih.gov/books/NBK138707/. Visited on July 1, 2021.

26. Bootdee S, Chantara S. Fine particulate matter and nitrogen dioxide emitted from incense burning at a shrine in Chiang Mai, Thailand. Int J Environ Sci Dev. 2014; 5: 228-232. doi:10.7763/IJESD.2014.V5.483

27. National Research Council (United States) Toxicology Committee. Sulfur dioxide. In: Emergency and continuous exposure limits for selected air pollutants. roll. 2. Washington (DC): National Academy of Sciences Press (United States); 1984. From: https://www.ncbi.nlm.nih.gov/books/NBK208295/. Visited on July 1, 2021.

28. Ali MU, Liu G, Yousaf B, Ullah H, Abbas Q, Munir MAM. A systematic review of the global pollution status and health perspectives of potentially toxic elements related to particulate matter in the urban environment. Environmental geochemical health. 2019;41(3):1131–1162. doi:10.1007/s10653-018-0203-z

29. Fang GC, Chang CN, Chu CC, et al. Fine particles (PM2.5), coarse particles (PM2.5-10) and metallic elements of incense burning at Ciyunyan Temple in central Taiwan. Chemistry circle. 2003;51(9):983–991. doi:10.1016/S0045-6535(03)00124-3

30. Fang GC, Chang CN, Wu YS, Yang CJ, Chang SC, Yang IL. Changes and mass distribution of suspended particles in Ciyun Temple, Taichung, Taiwan[J]. Science Total Environment. 2002;299(1-3):79-87. doi:10.1016/s0048-9697(02)00227-9

31. Lung SC, Kao MC. Believers in two temples in Taiwan were exposed to particulate matter. J Air Waste Management Association. 2003;53(2):130–135. doi:10.1080/10473289.2003.10466140

32. Fang GC, Lin SJ, Lee JF, Chang CC. Study on the concentration of particles and metal elements in temples. Toxicology Industrial Health. 2009;25(2):93–100. doi:10.1177/0748233709105594

33. Mannix RC, Nguyen KP, Tan EW, Ho EE, Phalen RF. The physical properties of aroma aerosols. The total environment of science. 1996;193(2):149-158. doi:10.1016/s0048-9697(96)05343-0

34. Nemmar A, Holme JA, Rosas I, Schwarze PE, Alfaro-Moreno E. Recent advances in particulate and nanoparticle toxicology: an overview of in vivo and in vitro studies. Biomedical Res Int. 2013; 2013: 279371. doi:10.1155/2013/279371

35. Dominici F, Peng RD, Bell ML, etc. Fine particulate air pollution and cardiovascular and respiratory diseases were hospitalized. Magazine. 2006;295(10):1127–1134. doi:10.1001/jama.295.10.1127

36. World Health Organization. Environmental (outdoor) air pollution. Available from: https://www.who.int/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health. Visited on June 31, 2021.

37. Lee CW, Vo TTT, Wu CZ, etc. The induction of environmental particulates in cancer progression through oxidative stress-mediated reactive oxygen species: recent observations. cancer. 2020;12(9):2505. doi:10.3390/cancers12092505

38. He SS, Yu Jizheng. The concentration of formaldehyde and other carbonyl compounds in the environment affected by incense. J Environmental monitoring. 2002;4(5):728-733. doi:10.1039/b200998f

39. Zhang Taiping, Chen Wenjun, Li Jianning, Yu Shijun, Zhao Wenjun. Volatile organic compounds and particulate pollution caused by incense burning in Chinese temples. Procedia Eng. 2015; 121: 992-1000. doi:10.1016/j.proeng.2015.09.067

40. Yang TT, Lin TS, Chang M. Emission characteristics of smoldering volatile organic compounds. Bull environment Contam Toxicol. 2007;78(5):308-313. doi:10.1007/s00128-007-9184-9

41. Nicolas M, Buiron D, Quivet E, Albinet A, Karr G, Maupetit F. The characteristics of the on-site activities of incense and candle discharge in the indoor environment. International Conference on Indoor Air Quality and Climate (Indoor Air 2016), Ghent, Belgium. 2016; ffineris-01863022.

42. Mahgoub H, Salih NA. Concentration levels of PAHs released by ebony incense: Baha City, southwestern Saudi Arabia. Modern Chemical Applications 2017; 5. doi:10.4172/2329-6798.1000201

43. Lin TC, Chang FH, Hsieh JH, Chao HR, Chao MR. Characteristics of indoor and outdoor atmospheric polycyclic aromatic hydrocarbons and total suspended particulates in a temple in Taiwan[J]. J Hazardous materials. 2002; 95(1–2):1–12. doi:10.1016/s0304-3894(02)00146-2

44. Lung SC, Kao MC, Hu SC. The contribution of incense to indoor PM10 and particulate-bound polycyclic aromatic hydrocarbons under two ventilation conditions. Indoor air. 2003;13(2):194-199. doi:10.1034/j.1600-0668.2003.00197.x

45. Bootdee S, Chantara S, Prapamontol T. Determination of PM2.5 and polycyclic aromatic hydrocarbons in shrine burning incense emissions for health risk assessment. Air pollution resources. 2016; 7(4): 680–689. doi:10.1016/j.apr.2016.03.002

46. ​​World Health Organization. Air pollution and cancer. IARC Scientific Publication No. 161. Available from the following URL: https://www.iarc.who.int/wp-content/uploads/2018/07/AirPollutionandCancer161.pdf. Visited on July 2, 2021.

47. O'Brien PJ, Siraki AG, Shangari N. Sources, metabolism, molecular toxicity mechanisms of aldehydes and possible effects on human health. Crit Rev Toxicol. 2005;35(7):609–662. doi:10.1080/10408440591002183

48. Masekameni MD, Moolla R, Gulumian M, Brouwer D. Risk assessment of the concentration of benzene, toluene, ethylbenzene and xylene from coal combustion in a controlled laboratory environment. Int J Environ Res Public Health. 2018;16(1):95. doi:10.3390/ijerph16010095

49. Kim KH, Jahan SA, Kabir E, Brown RJ. A review of polycyclic aromatic hydrocarbons (PAHs) in the air and their effects on human health. Environment International 2013; 60: 71-80. doi:10.1016/j.envint.2013.07.019

50. Hayakawa R, Matsunaga K, Arima Y. Contact dermatitis with discoloration due to fragrance. Contact dermatitis. 1987;16(5):272-274. doi:10.1111/j.1600-0536.1987.tb01451.x

51. Hayakawa R, Matsunaga K, Arima Y. Airborne pigmented contact dermatitis caused by musk in incense. Contact dermatitis. 1987;16(2):96-98. doi:10.1111/j.1600-0536.1987.tb01387.x

52. Ho CK, Tseng WR, Yang CY. The adverse effects of Taiwanese temple workers on the respiratory system and irritant health. J Toxicol Environ Health A. 2005; 68(17–18):1465–1470. doi:10.1080/15287390590967405

53. Norbäck D, Zhang X, Fan Q, et al. Home environment and health: domestic risk factors for rhinitis, throat symptoms and non-respiratory symptoms in Chinese adults. The total environment of science. 2019; 681: 320-330. doi:10.1016/j.scitotenv.2019.05.084

54. Hsu NY, Wang JY, Wu PC, Su HJ. Paternal inheritance and housing characteristics affect the incidence of childhood asthma and allergies. The Arch environment takes up health. 2012; 67(3): 155–162. doi:10.1080/19338244.2011.598890

55. Zhang Z, Tan L, Huss A, etc. Family incense and children's respiratory health: a cohort study in Hong Kong. Pediatric pulmonary heart disease. 2019;54(4):399–404. doi:10.1002/ppul.24251

56. Yang CY, Chiu JF, Cheng MF, Lin MC. The influence of indoor environmental factors on children's respiratory system health in subtropical climate[J]. Environmental Resources 1997;75(1):49-55. doi:10.1006/enrs.1997.3774

57. Al-Rawas OA, Al-Maniri AA, Al-Riyami BM. Family exposure to bakhour and childhood asthma symptoms: a community survey in two regions of Oman. BMC Pulm Med. 2009; 9:23. doi:10.1186/1471-2466-9-23

58. Wang IJ, Tsai CH, Chen CH, Tung KY, Lee YL. Glutathione S-transferase, incense and childhood asthma. Eur Respir J. 2011;37(6):1371–1377. doi:10.1183/09031936.00137210

59. Koo LC, Ho JC, Tominaga S, etc. Is Chinese incense smoke harmful to respiratory health? : Epidemiological results from Hong Kong. indoor environment. 1995; 4(6): 334–343. doi:10.1177/1420326X9500400604

60. Guo Se, Chi MC, Lin CM, Yang TM. The contribution of incense to indoor air pollution levels and the health of patients with chronic obstructive pulmonary disease. Pell J. 2020; 8: e9768. doi:10.7717/peerj.9768

61. Døssing M, Khan J, al-Rabiah F. Risk factors for chronic obstructive pulmonary disease in Saudi Arabia. Respiratory medicine. 1994;88(7):519-522. doi:10.1016/s0954-6111(05)80334-8

62. Alarifi SA, Mubarak M, Alokail MS. Ultrastructure of rat alveolar cells exposed to Ma`amoul. J Biological Sciences. 2004; 4(6): 694-699. doi:10.3923/jbs.2004.694.699

63. Alarifi SA, Mubarak MM, Alokail MS. Ultrastructural changes in rat lung cells exposed to Bakhour. Saudi Medical Journal 2004; 25(11): 1689-1693.

64. Kammoolkon R, Taneepanichskul N, Pitaknoppakul N, Lertmaharit S, Lohsoonthorn V. Incense and increasing carotid artery intima thickness: a cross-sectional study of the Thai-Vietnamese community. Asia Pacific J Public Health. 2018;30(2):178-187. doi: 10.1177/1010539517753930

65. Kasliwal RR, Bansal M, Desai D, Sharma M. Carotid artery intima-media thickness: current evidence, practice, and Indian experience. Indian J Journal of Endocrinology and Metabolism. 2014;18(1):13-22. doi:10.4103/2230-8210.126522

66. Huang YL, Chen HW, Han BC, et al. Personal exposure of housewives to household particulate matter, household activities and heart rate variability. Public Science Library One. 2014;9(3):e89969. doi:10.1371/journal.pone.0089969

67. Alokail MS, Al-Daghri NM, Alarifi SA, Draz HM, Hussain T, Yakout SM. Long-term exposure to incense will change the metabolism of Wistar albino rats. Cell biochemical function. 2011;29(2):96–101. doi:10.1002/cbf.1726

68. Al-Attas OS, Hussain T, Ahmed M, etc. Ultrastructural changes, increased oxidative stress, inflammation and cardiac hypertrophy gene expression changes in the heart tissue of rats exposed to cigarettes. Environ Sci Pollut Res Int. 2015;22(13):10083–10093. doi:10.1007/s11356-015-4212-5

69. Weber LP, Al-Dissi A, Marit JS, Germany TN, Terletski SD. The role of carbon monoxide in the damage of endothelial function mediated by acute exposure to second-hand tobacco, incense and candle smoke. Environmental Toxicology Pharmacology. 2011; 31(3): 453–459. doi:10.1016/j.etap.2011.02.008

70. Lin LY, Lin HY, Chen HW, Su TL, Huang LC, Chuang KJ. The influence of Temple granule on inflammation and endothelial cell response. The total environment of science. 2012; 414: 68-72. doi:10.1016/j.scitotenv.2011.08.050

71. Song X, Ma Wei, Xu X, et al. The relationship between household incense and hypertension and blood pressure in Guangdong Province, China. Int J Environ Res Public Health. 2017;14(7):788. doi:10.3390/ijerph14070788

72. He JR, Wei DM, Chan FF, et al. The relationship between mothers' exposure to incense and blood pressure during pregnancy. The total environment of science. 2018; 610–611:1421-1427. doi:10.1016/j.scitotenv.2017.08.134

73. Wong A, Lou W, Ho KF, etc. Indoor incense will affect the cognitive function and brain function of the elderly in the community. Scientific Reports 2020; 10(1): 7090. doi:10.1038/s41598-020-63568-6

74. Fang XY, Strodl E, Liu BQ, et al. The association between prenatal exposure to household inhalants and ADHD-like behaviors around 3 years of age: Results of the Shenzhen Longhua Children's Cohort Study. Environmental Resources 2019;177:108612. doi:10.1016/j.envres.2019.108612

75. Wei CF, Chen MH, Lin CC, et al. Family burning incense and infant gross motor development: results from a Taiwan birth cohort study. Environment International 2018; 115: 110-116. doi:10.1016/j.envint.2018.03.005

76. Chen LY, Ho C. Birth weight and head circumference of incense burning during pregnancy and full-term delivery: a Taiwanese birth cohort study. Environmental health perspective. 2016;124(9):1487–1492. doi:10.1289/ehp.1509922

77. Chattopadhyay N, Mitra K. Neurodevelopmental outcomes of high-risk newborns discharged from special care infant wards in rural India. J Public Health Research. 2015;4(1):318. doi:10.4081/jphr.2015.318

78. Tian Y, Zhang C, Yu G, Hu X, Pu Z, Ma L. Influencing factors of neurodevelopment in high-risk infants. Psychiatrist. 2018;31(3):e100034. doi:10.1136/gpsych-2018-100034

79. Zhou Rui, An Qing, Pan Xinwei, Yang B, Hu Jie, Wang Yonghui. The cytotoxicity and genetic toxicity of burning incense are higher than that of cigarettes. Environmental Chemistry Communications. 2015; 13: 465-471. doi:10.1007/s10311-015-0521-7

80. Chang HL, Kuo ML, Lin JM. Compared with the formaldehyde and acetaldehyde in Salmonella typhimurium TA102, the mutagenic activity of cigarettes. Bull environment Contam Toxicol. 1997;58(3):394-401. doi:10.1007/s001289900347

81. Chen CC, Lee H. Genotoxicity and DNA adduct formation of cigarette condensate: comparison with environmental tobacco smoke condensate. Mutant Reservoir. 1996;367(3):105-114. doi: 10.1016/0165-1218(95)00067-4

82. MacLennan R, Da Costa J, Day NE, Law CH, Ng YK, Shanmugaratnam K. The risk factors of lung cancer among Chinese in Singapore are high in females. International J Cancer. 1977; 20(6): 854-860. doi:10.1002/ijc.2910200606

83. Chan-Yeung M, Koo LC, Ho JC, etc. Related risk factors of lung cancer in Hong Kong. Lung cancer. 2003;40(2):131–140. doi:10.1016/s0169-5002(03)00036-9

84. Tang L, Lim WY, Eng P, etc. Lung cancer in Chinese women: Evidence for the interaction between smoking and exposure to indoor environmental inhalants. Environmental health perspective. 2010;118(9):1257–1260. doi:10.1289/ehp.0901587

85. Xie SH, Yu IT, Tse LA, etc. Burning incense and nasopharyngeal cancer: a case-control study of Chinese in Hong Kong. Environmental molecular mutagens. 2014;55(9):751–756. doi:10.1002/em.21894

86. He YQ, Xue WQ, Shen GP, ​​Tang LL, Zeng YX, Jia WH. Household inhalation exposure and nasopharyngeal cancer risk: a large-scale case-control study in Guangdong, China. BMC cancer. 2015; 15:1022. doi:10.1186/s12885-015-2035-x

87. Lowengart RA, Peters JM, Cicioni C, etc. Childhood leukemia and parents’ occupational and family exposure. J Natl Cancer Institute. 1987;79(1):39-46.

88. Preston-Martin S, Yu MC, Benton B, Henderson BE. N-nitroso compounds and childhood brain tumors: a case-control study. Cancer research. 1982; 42(12): 5240-5245.

89. Kuijten RR, Bunin GR, Nass CC, Meadows AT. Pregnancy and family risk factors for childhood astrocytoma: the results of a case-control study. Cancer research. 1990;50(9):2608-2612.

90. Bunin GR, Buckley JD, Boesel CP, Rorke LB, Meadows AT. Risk factors for astrocytoma and primitive neuroectodermal tumors in young children: a report by the Childhood Cancer Group. Biomarkers of Cancer Epidemiology 1994;3(3):197-204.

91. Hong DZ, Yang KW, Wu CC, Hung YH. Burning incense lead poisoning: a family outbreak. Clinical Toxicology. 2020; 1-6. doi:10.1080/15563650.2020.1853146

92. Hwang YH, Lin YS, Lin CY, Wang IJ. Burning incense at home and blood lead levels of preschool children in Taiwan[J]. Environ Sci Pollut Res Int. 2014;21(23):13480–13487. doi:10.1007/s11356-014-3273-1

93. Hussain T, Al-Attas OS, Alrokayan SA, etc. The harmful effects of incense smoke on the renal function and structure of male albino rats. Inhalation of poison. 2016;28(8):364–373. doi:10.1080/08958378.2016.1179372

94. Sies H, Berndt C, Jones DP. Oxidative stress. Annu Rev Biochem. 2017; 86: 715-748. doi:10.1146/annurev-biochem-061516-045037

95. Sies H. On the history of oxidative stress: concepts and certain aspects of current developments. Curr Opin Toxicol. 2018; 7: 122-126. doi:10.1016/j.cotox.2018.01.002

96. Pizzino G, Irrera N, Cucinotta M, etc. Oxidative stress: harm and benefits to human health. Oxid Med Cell Longev. 2017; 2017: 8416763. doi:10.1155/2017/8416763

97. Sies H, Jones DP. Reactive oxygen species (ROS) act as a multi-effect physiological signal agent. Nat Rev Mol Cell Biology. 2020; 21(7):363–383. doi:10.1038/s41580-020-0230-3

98. Sies H. Oxidative stress: oxidants and antioxidants. Experimental physiology. 1997;82(2):291-295. doi:10.1113/expphysiol.1997.sp004024

99. Bhattacharyya A, Chattopadhyay R, Mitra S, Crowe SE. Oxidative stress: an important factor in the pathogenesis of gastrointestinal mucosal diseases. Revised Physiology 2014;94(2):329-354. doi:10.1152/physrev.00040.2012

100. Chen KF, Tsai YP, Lai CH, Xian YK, Chuang KY, Zhu ZH. Human health risk assessment based on long-term exposure to carbonyl compounds and metals emitted by burning incense in temples. Environ Sci Pollut Res Int. 2020; 2:154.

101. Liao CM, Chen SC, Chen JW, Liang HM. The contribution of Chinese cooking and burning incense to personal exposure and residents' PM concentration in Taiwan. The total environment of science. 2006;358(1–3):72–84. doi:10.1016/j.scitotenv.2005.03.026

102. Chuang HC, Jones TP, Lung SC, BéruBé KA. Active oxygen species driven by soot are formed from the burning of incense. The total environment of science. 2011;409(22):4781–4787. doi:10.1016/j.scitotenv.2011.07.041

103. Chuang HC, Jones T, Chen Y, Bell J, Wenger J, BéruBé K. Characterization of airborne particles and related organic components produced by incense burning. Anal biology anal chemistry. 2011;401(10):3095-3102. doi:10.1007/s00216-011-5209-7

104. Tran TC, Marriott PJ. Integrated two-dimensional gas chromatography-time-of-flight mass spectrometry and simultaneous electron capture detection/nitrogen and phosphorus detection for aroma analysis. Atmospheric Environment. 2008; 42: 7360-7372. doi:10.1016/j.atmosenv.2008.06.028

105. Semchyshyn HM. Reactive carbonyl substances in the body: generation and dual biological effects. Science World Magazine. 2014; 2014: 417842. doi:10.1155/2014/417842

106. Bolton JL, Dunlap T. Quinone formation and biological targets: cytotoxicity and cytoprotection. Chemical research toxicology. 2017;30(1):13-37. doi:10.1021/acs.chemrestox.6b00256

107. Aust SD, Morehouse LA, Thomas CE. The role of metals in oxygen radical reactions. J Free Radical Biomedicine. 1985;1(1):3-25. doi:10.1016/0748-5514(85)90025-x

108. Kobayashi R, Liu X, Wong P, et al. Assessment of the health effects of indoor air source particulate matter Phase 1: Development of in vitro methods; 2010. Available from: https://ww2.arb.ca.gov/sites /default/files/classic//research/apr/past/05-302.pdf. Visited on July 2, 2021.

109. Hussain T, Al-Attas OS, Al-Daghri NM, etc. The induction of CYP1A1, CYP1A2, and CYP1B1 increased oxidative stress and inflammation in lung and liver tissues of rats exposed to cigarettes. Moore Cell Biochemistry. 2014;391(1–2):127–136. doi:10.1007/s11010-014-1995-5

110. Sies H. Oxidative stress: concept and some practical aspects. Antioxidants. 2020; 9(9):852. doi:10.3390/antiox9090852

111. Ighodaro OM, Akinloye OA. First-line defense antioxidants-superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX): their basic role in the entire antioxidant defense network. Alexander J, MD. 2018;54(4):287–293. doi:10.1016/j.ajme.2017.09.001

112. Mr. Aquilano K, Baldelli S, Ciriolo. Glutathione: the new role of old antioxidants in redox signaling. Former pharmacist. 2014; 5:196. doi:10.3389/fphar.2014.00196

113. Ji LL, Yeo D. Oxidative stress: an evolving definition. Fac revision 2021; 10:13. doi:10.12703/r/10-13

114. Chuang HC, Jones T, Chen TT, BéruBé K. Cytotoxic effects of fragrance particles related to oxidative stress, cell cycle and F-actin assembly. Toxicology Wright. 2013;220(3):229-237. doi:10.1016/j.toxlet.2013.05.004

115. Hussain T, Alamery S, Dikshit G, Mohammed AA, Naushad SM, Alrokayan S. Incense can increase systemic oxidative stress, inflammation and endothelial dysfunction in male albino rats. Toxicological methods. 2019;29(3):211–218. doi:10.1080/15376516.2018.1544681

116. Singh Z, Karthigesu I, Singh P, Kaur R. Using malondialdehyde as a biomarker to assess oxidative stress in different disease pathologies: a review. Iran J Public Health. 2014; 43: 7-16.

117. Niu X, Jones T, Béru Bé K, Chuang HC, Sun J, Ho KF. The oxidation capacity of particulate matter produced by indoor source combustion and the resulting respiratory toxicity. The total environment of science. 2021;767:144391. doi:10.1016/j.scitotenv.2020.144391

118. Navasumrit P, Arayasiri M, Hiang OM, etc. The potential health effects of exposure of temple staff to carcinogenic compounds in incense smoke. Chemical biological interaction. 2008;173(1):19-31. doi:10.1016/j.cbi.2008.02.004

119. Menck CF, Munford V. DNA repair diseases: what do they tell us about cancer and aging? Genetic molecular biology. 2014; 37 (1 supplement): 220-233. doi:10.1590/s1415-47572014000200008

120. Paz-Elizur T, Sevilya Z, Leitner-Dagan Y, Elinger D, Roisman LC, Livneh Z. DNA repair of oxidative DNA damage in human carcinogenesis: potential applications for cancer risk assessment and prevention. Cancer Letters. 2008;266(1):60–72. doi:10.1016/j.canlet.2008.02.032

121. Cooke MS, Evans MD, Dizdaroglu M, Lunec J. Oxidative DNA damage: mechanisms, mutations and diseases. FASEB J. 2003;17(10):1195-1214. doi:10.1096/fj.02-0752rev

122. Haberzettl P, Bhatnagar A, Conklin DJ. Particulate matter and oxidative stress-lung and cardiovascular goals and consequences, in: Laher I, editor. System biology of free radicals and antioxidants. Berlin, Heidelberg: Springer; 2014. Available from. Visited on July 3, 2021.

123. Gangwar RS, Bevan GH, Palanivel R, Das L, Rajagopalan S. Oxidative stress pathways of air pollution-mediated toxicity: recent insights. Redox organisms. 2020;34:101545. doi:10.1016/j.redox.2020.101545

124. Valavanidis A, Vlachogianni T, Fiotakis K, Loridas S. Pulmonary oxidative stress, inflammation and cancer: Inhalable particulate matter, fiber dust and ozone are the main causes of lung cancer through the mechanism of reactive oxygen species. Int J Environ Res Public Health. 2013; 10(9): 3886-3907. doi:10.3390/ijerph10093886

125. Rao X, Zhong J, Brook RD, Rajagopalan S. The effect of particulate air pollution on cardiovascular oxidative stress pathways. Anti-oxidant redox signal. 2018;28(9):797–818. doi:10.1089/ars.2017.7394

126. Pease JE, Sabroe I. The role of interleukin-8 and its receptors in inflammatory lung disease: implications for treatment. This is J Respir Med. 2002;1(1):19-25. doi:10.1007/BF03257159

127. Rumzhum NN, Ammit AJ. Cyclooxygenase 2: its regulation, role and influence in airway inflammation. Clinical experiment allergy. 2016;46(3):397–410. doi:10.1111/cea.12697

128. Simkhovich BZ, Kleinman MT, Kloner RA. The epidemiology, toxicology and mechanism of air pollution and cardiovascular injury. J Am Coll Cardiol. 2008;52(9):719–726. doi:10.1016/j.jacc.2008.05.029

129. Li H, Horke S, Förstermann U. Vascular oxidative stress, nitric oxide and atherosclerosis. Atherosclerosis. 2014;237(1):208-219. doi:10.1016/j.atherosclerosis.2014.09.001

130. Sena CM, Leandro A, Azul L, Seiça R, Perry G. Vascular oxidative stress: effects and treatment methods. Pre-physiology. 2018; 9:1668. doi:10.3389/fphys.2018.01668

131. Kanda T, Takahashi T. Interleukin-6 and cardiovascular disease. Jpn Heart J. 2004;45(2):183-193. doi:10.1536/jhj.45.183

132. Marasciulo FL, Montagnani M, Potenza MA. Endothelin-1: The influence of yin and yang on blood vessel function. Curr Med Chem. 2006;13(14):1655–1665. doi:10.2174/092986706777441968

133. Manoukian A, Quivet E, Temime-Roussel B, Nicolas M, Maupetit F, Wortham H. The emission characteristics of air pollutants from incense and candle burning in indoor air. Environ Sci Pollut Res Int. 2013;20(7):4659-4670. doi:10.1007/s11356-012-1394-y

134. Manoukian A, Buiron D, Temime-Roussel B, Wortham H, Quivet E. Measure the VOC/SVOC emission factors of burning incense in the environmental laboratory: the influence of temperature, relative humidity and air exchange rate. Environ Sci Pollut Res Int. 2016;23(7):6300–6311. doi:10.1007/s11356-015-5819-2

135. Lin TC, Yang CR, Chang FH. Combustion characteristics and emission products related to the metal content of the incense. J Hazardous materials. 2007;140(1–2):165–172. doi:10.1016/j.jhazmat.2006.06.052

136. Dryden GW, Deaciuc I, Arteel G, McClain CJ. The clinical significance of oxidative stress and antioxidant therapy. Curr Gastroenterol Rep. 2005;7(4):308-316. doi:10.1007/s11894-005-0024-y

137. Christofidou-Solomidou M, Muzykantov VR. Antioxidant strategies in respiratory medicine. Therapeutic Respiratory Medicine. 2006;5(1):47–78. doi:10.2165/00151829-200605010-00004

138. Wang Wei, Premier Kang. Oxidative stress and antioxidant therapy in cardiovascular disease. Antioxidants. 2020;9(12):1292. doi:10.3390/antiox9121292

139. Koo LC, Ho JH. Diet as a confounding factor in the association between air pollution and female lung cancer: A study in Hong Kong taking exposure to environmental tobacco smoke, incense and cooking fumes as examples. Lung cancer. 1996; 14 (Supplement 1): S47-S61. doi:10.1016/s0169-5002(96)90210-x

140. Löfroth G, Stensman C, Brandhorst-Satzkorn M. Indoor sources of mutagenic aerosol particles: smoking, cooking and incense. Mutant Reservoir. 1991;261(1):21-28. doi: 10.1016/0165-1218(91)90094-3

141. Cheng YS, Bechtold WE, Yu CC, Hung IF. Cigarettes: characteristics and dynamics in the indoor environment. Aerosol science and technology. 1995;23(3):271-281. doi:10.1080/02786829508965312

142. Caliri AW, Tommasi S, Besaratinia A. The relationship between smoking, oxidative stress, inflammation, macromolecular damage and cancer. Mutat Res Rev Mutat Res. 2021;787:108365. doi:10.1016/j.mrrev.2021.108365

This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and include the Creative Commons Attribution-Non-commercial (unported, v3.0) license. By accessing the work, you hereby accept the terms. The use of the work for non-commercial purposes is permitted without any further permission from Dove Medical Press Limited, provided that the work has an appropriate attribution. For permission to use this work for commercial purposes, please refer to paragraphs 4.2 and 5 of our terms.

Contact Us• Privacy Policy• Associations and Partners• Testimonials• Terms and Conditions• Recommend this site• Top

Contact Us• Privacy Policy

© Copyright 2021 • Dove Press Ltd • Software development of maffey.com • Web design of Adhesion

The views expressed in all articles published here are those of specific authors and do not necessarily reflect the views of Dove Medical Press Ltd or any of its employees.

Dove Medical Press is part of Taylor & Francis Group, the academic publishing department of Informa PLC. Copyright 2017 Informa PLC. all rights reserved. This website is owned and operated by Informa PLC ("Informa"), and its registered office address is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 3099067. UK VAT group: GB 365 4626 36

In order to provide our website visitors and registered users with services that suit their personal preferences, we use cookies to analyze visitor traffic and personalize content. You can understand our use of cookies by reading our privacy policy. We also retain data about visitors and registered users for internal purposes and to share information with our business partners. By reading our privacy policy, you can understand what data we retain, how we process it, who we share it with, and your right to delete data.

If you agree to our use of cookies and the content of our privacy policy, please click "Accept".