Health Risk Assessment Of Children Exposed To Trihalomethane In Indoor Swimming Pools In Summer

Objective:This study aimed to understand the exposure levels of trihalomethanes(THMs)in indoor swimming pools in summer and the related exposure factors of swimmers aged 6?17 years,and to conduct a health risk assessment and systematic review of THMs exposure to swimmers aged 6?17 Children's lifetime carcinogenic and non-carcinogenic risks in indoor swimming places in Beijing,ChinaMethod:Taking an indoor swimming pool A in Beijing as the research site and taking 6?17 year-old children swimmers swimming in swimming pool A as the study subjects,the relevant exposure factors of children swimmers in the swimming pool were investigated by questionnaire survey.The THMs in swimming pool water,shower water,stadium air,and locker room air in the swimming pool were sampled and sent to the laboratoryto test the concentration levels.The survey data was entered using Epidata 3.1,and the obtained data was subjected to rank sum test and Speannan correlation analysis through SPSS 22.0.Finally,based on the results of questionnaire surveys and laboratory tests,and referring to the United States Environmental Protection Agency(USEPA)exposure model,health risk assessment was performed on children swimmers exposed to THMs in swimming places.Results:Through questionnaire survey and laboratory test,the basic exposure factors and THMs concentrations required for health risk assessment were obtained.Finally,the health risk assessment was conducted with USEPA exposure model.The main results are as follows:(1)According to the questionnaire survey,the average weight of children swimmers aged 6-17 is 40.46 kg,the average swimming duration is 2 years.The swimming frequency is about 4 events/month.The swimming time,shower time,dressing time,preparation activity and rest time are 59 min/event,15 min/event,11 min/event,10 min/event,respectively.The body surface area is 1.369 m2,and the water consumption is 40.50 mL/event.Compared with female children swimmers,the swimming frequency of male children swimmers was slightly lower,while the length of changing clothes and showering was significantly longer than that of male children swimmers(P<0.05).There was no significant difference in other factors.There were some differences in swimming duration,swimming frequency and swimming time in different age groups,and the differences were statistically significant(P<0.05).There was no significant difference in other factors.Some exposure factors were correlated,among which dressing time was positively correlated with shower time in a low degree(r=0.347)(2)The concentrations of THMs in swimming pool water,shower water,air around the swimming pool and dressing room air in a swimming place in Beijing were measured by laboratory test.The average concentrations of THMs in swimming pool water,female shower water and male shower water were 67.17?g/L,13.03 ?g/L and 12.25 ?g/L,respectively.The concentrations of THMs in the air around the swimming pool and in the changing room were 358.66 ?g/m3.40.97 ?g/m3 and 40.98 ?g/m3,respectively.The concentrations of four species of THMs in each water sample were quite different,TCM was the highest,accounting for 93%?97%of THMs,while DBCM and TBM were the lowest,and these two kinds of THMs were not detected in the air of male and female dressing rooms(3)Children aged 6?17 years are exposed to THMs in indoor swimming pools,and there is a certain cancer risk.TCM is the main exposure substance.Through inhalation is the main exposure pathway of THMs,accounting for 99%of the total risk of all exposure pathways.In this study,the risk of THMs in the whole year is estimated from the summer child swimmer's behavior pattern.If the summer swimming behavior pattern is maintained throughout the year,the cancer risk of TCM through inhalation in children aged 6?8,9?11,12?14 and 15?17 years was 2.59×10-6,6.69×10-6,8.15×10-6 and 9.56×10-6,respectively.The cancer risk of TCM in boys and girls was 6.69×10-6 and 5.40×10-6,respectively.The non-carcinogenic risk of children aged 6-17 exposed to THMs was less than 1.It means that non-carcinogenic risk was not significant.Conclusion:The main conclusions are as follows:(1)The study found that the duration of non-swim sports such as showers,changing clothes,warm-up activities and rest accounted for about 40%of the total time,which was only slightly lower than the proportion of swimming activities(60%),which indicated that there is also a certain risk during non-swim sports.Therefore,when conducting health risk assessment,the risks arising from other non-swim sports such as showers and changing clothes should also be included in the corresponding exposure models to facilitate a more comprehensive health risk assessment at a later stage(2)Judging from the THMs laboratory test results,the concentration of THMs in the air is high.China should formulate relevant standards for the concentration of THMs in the air of swimming places,and take various measures(such as improving disinfection methods)to reduce the THMs concentrations in water and air in swimming places.(3)If the summer swimming behavior pattern is maintained throughout the year,the carcinogenic risk value is higher than the USEPA recommended value,indicating that there is a certain carcinogenic risk.Among them,TCM is the main carcinogen,and through inhalation is the main exposure pathway.Swimming pools should strengthen public health education on swimming pool hygiene and control the production of precursor substances(such as urea,hair,cosmetic residues,etc.)that are disinfection by-products in swimming pool water.Thereby reducing the risk of carcinogenic and non-carcinogenic,providing a safe and clean sports space for humans.