| Objective: Trihalomethane(THMs)is an organic by-product of chlorination treatment in indoor swimming poor,which can be harmful to human health.In recent years,the research on THMs mainly focuses on drinking water or tap water,and there are few studies on THMs in natatorium with more complicated actual situation.Therefore,this research through detected concentration of THMs contents in different location of the swimming pool,water and air,and analyzed the relationship between THMs and environmental factors,in order to understand the THMs distribution characteristics and influencing factors in indoor swimming pool,evaluate the health risks of THMs.This play an important role in developing effective management measures and reducing the swimmer THMs exposure,thus avoiding the potential risk of swimming.Methods: In this study,The concentrations of THMs in the water and air samples in different sampling times(T1-8: 00,T2-12: 00,T3-18: 00,T4-20:00)and different locations(shallow water area,deep water area,immersion foot disinfection pool area,and shower room)in the 2018 off-season(autumn)and the 2019 peak-season(summer)were tested,compare and analyze the differences in time and space;Recorded environmental factors such as free chlorine(FCR),ammonia nitrogen(AN),pH,water temperature(T),relative humidity(RH),and number of swimmers(CNS),and analyzed the correlation between these environmental factors and THMs;SPSS25.0software was used to analyze the exposure characteristics of trihalomethanes.R and Prism software were used to analyze and plot.The average daily THMs exposure and lifetime carcinogenic risk of swimmers were calculated by Excel.To evaluate the environmental health risks of trihalomethanes in swimming pools;SPSS25.0 software was used to statistics the characteristics of trihalomethane exposure,R software and Prism software were used toanalyze and plot,and the average daily exposure of trihalomethane and lifetime carcinogenic risk of swimmers were calculated by Excel.The exposure characteristics of THMs were summarized,and the environmental health risk of trihalomethane in natatorium was evaluated.Results:(1)Time distribution of THMs in indoor swimming poor: the concentration of TCM at T2 in off-season was significantly higher than T3(p<0.05).During peak season,TCM concentration at T1 was significantly higher than other three time points,and TTHMs concentration at T1 was significantly higher than T4.At the seasonal level,at the same sampling time,TCM and BDCM were significantly higher in the off-season than in the peak season(p<0.05).(2)Spatial distribution of THMs in indoor swimming pools: The concentrations of TCM,BDCM,and TTHMs in the pool area are significantly higher than those in the immersion pool water and bathroom tap water(p <0.05);The concentration of DBCM in pool water was higher than that in the pool water,and the concentration of TBM in tap water is significantly higher than in other areas(p <0.05);the proportion of TCM and BDCM was larger in the pool water area;the proportion of DBCM and TBM was larger in the tap water and immersion foot disinfection pool area.(3)The correlation between THMs and environmental factors showed that in the off-season,BDCM was negatively correlated with FCR,PH,RAH and CNS(p <0.05),and positively correlated with AN(p <0.05).During peak season,TCM and TTHMs were positively correlated with FCR,negatively correlated with RAH and CNS,and TCM positively correlated with and PH value.(4)Exposure amount of THMs and carcinogenic risk: from the perspective of exposure route,TCM exposure amount in the peak season was shown as respiratory tract inhalation > skin contact absorption > digestive tract intake,carcinogenic risk was shown as skin contact absorption >respiratory tract inhalation > digestive tract intake.From the perspective of THMs in general: in the two exposure pathways of digestive tract intake and skin contact absorption,the exposure volumes of the four substances in the peak season were all sequentially arranged as follows:TCM>BDCM>DBCM>TBM;However,under the digestive tract intake route,the carcinogenic risk of THMs was DBCM> BDCM> TCM> TBM.Conclusion:(1)The time distribution of THMs in indoor swimming poor was different.With the extension of sampling time,the concentration of THMs decreased.(2)The spatial distribution of THMs in indoor swimming poor was different.Generally speaking,the concentration of THMs in pool area was higher than other areas.(3)THMs concentration was closely related to environmental factors,and the correlation was complex.Some environmental factors had different relationships under different conditions.(4)The exposure route of THMs was mainly respiratory inhalation,and skin contact absorption of THMs had a greater carcinogenic risk than respiratory inhalation and ingestion.(5)The indoor swimming poor should strengthen daily environmental monitoring,increase vents,reduce THMs concentration,regulate swimmers' behavior,and prevent excessive exposure to THMs. |
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