Risk Assessment Of Polycyclic Aromatic Hydrocarbon Exposure From Incense And Candle Burning In The Indoor Environments

There are always sources of pollutants such as heating,smoking and cooking in the indoor environment,which can produce large amounts of Polycyclic Aromatic Hydrocarbons?PAHs?.PAHs is absorbed by the human body through breathing,skin absorption,dietary intake and other channels.It is one of the environmental chemical carcinogenic compounds with the largest variety,the widest distribution range and the greatest degree of harm.Studies have shown that PAHs has carcinogenic,mutagenic and teratogenic toxic effects,and there is a significant dose-effect relationship between the concentration of PAHs in the environment and the prevalence of population.Therefore,this paper combined the differential equation of PM_2.5 emission rate with the PM_2.5 and PAHs emission characteristics to simulate and predict the exposure time and concentration level of PAHs generated by lighting 3 incense sticks or 1 candle in the room.The volume of the room is 40m3and the number of air changes is 1 per hour.The PM_2.5 and PAHs emission characteristics were measured by the research group in the experimental cabin.Then,point estimation model and Crystal ball software based on non-threshold model were used to evaluate the carcinogenic risk of indoor PAHs.Meanwhile,the uncertainty of PAHs exposure risk is analyzed by comparing with PAHs data of the coke oven plant and using Crystal ball software.Finally,the paper analyzes and discusses the differences and reasons of the evaluation results of different models by comparing the risk assessment results of incenses and candles.The main conclusions are as follows:?1?The mass concentration of PAHs produced by lighting three incense sticks in the room ranges from 235.28 to 3120.22 ng/m3,the equivalent concentration of benzo?a?pyrene is within the range of 2353.54 to 23391.58 pg/m3,and the equivalent concentration of benzo?a?pyrene produced by seven kinds of incense exceeds the daily BaP limit?2.5ng/m3?.The mass concentration range of PAHs produced by lighting one candle is 62.70⁵43.48 ng/m3,and the equivalent concentration of benzo?a?pyrene is within the range of 125.12¹503.93 pg/m3.The candle does not exceed the standard.?2?Burning incenses indoor produces PAHs lifetime lung cancer risk of adults within the range of 1.82×10^-53.15×10^-4,with potential carcinogenic risk or even serious carcinogenic risk.The variability of lifetime lung cancer risk is within the range of 0.93².12,indicating that it is feasible to apply the epidemiological data of the coke oven plant to evaluate the lifetime lung cancer risk of PAHs produced by burning incenses.?3?Burning one candle indoor results in PAHs lifetime lung cancer risk of adults is within the range of 1.66×10^-62.01×10^-5,with potential carcinogenic risk.The variability of lifetime lung cancer risk is within the range of 0.99².2,indicating that it is feasible to evaluate the lifetime lung cancer risk of PAHs generated by burning one candle with the epidemiological data of coke oven plant.?4?The incremental lifetime carcinogenic risk of PAHs caused by burning incenses and one candle indoor is logarithmic normal distribution.The median values of the incremental lifetime carcinogenic risk of PAHs generated by burning incenses for adults,children and infants is within the range of 9.58×10^-81.66×10^-6,3.35×10^-85.82×10^-7,and 2.22×10^-93.85×10^-8,respectively,and adults have a potential cancer risk.The median values of the incremental lifetime cancer risk of PAHs generated by burning one candle are in the range of8.56×10^-91.04×10^-7,2.99×10^-93.64×10^-8,and 1.98×10^-102.41×10^-9,respectively,and are within the acceptable range.?5?Through quantitative sensitivity analysis of the incremental lifetime carcinogenic risk of adults,children and infants,it is assumed that the contribution rate of variables to uncertainty from high to low is the carcinogenic slope factor,respiratory rate and body weight,respectively,and the carcinogenic slope factor is the key factor to improve the accuracy of the risk value.?6?In the same environment,incenses and candles are compared.The burning quality of a single candle is 1.01⁸6.28 times that of a single incense.The burning time of the candle is0.64¹0.21 times of that of incense.The emission rate of PM_2.5 produced by burning a single stick of incense is 0.17¹35.53 times that of a candle.The total PAHs emission factor produced by burning incenses is 1.53²02.39 times that of candles.?7?The risk assessment result of the point estimation model is about two orders of magnitude higher than that of the non-threshold model,because the carcinogenic slope factor and inhalational unit risk values.?8?In the absence of population epidemiological survey data,it is suggested to use the non-threshold model to evaluate the risk of PAHs from burning incenses and candles,and the result of the point estimation model can be used as a reference value.?9?This paper provides basic data for people to understand the PAHs pollution level generated by burning incenses and candles indoor,and meanwhile provides scientific basis for environmental managers to prevent and control PAHs pollution.