Simulation Method And Human Health Risk Assessment Of Trihalomethanes In Natatorium

Flaws of previous studies were in the following aspects:modelling of environmental systems,like natatorium,failed to quantitatively consider the impact of customer behaviors;the exposure in showering and dressing during swimming activities were usually neglected in health risk assessment of swimmers;few researches focused on the health risk assessment of staff members in natatorium.Aimed at filling the gaps of those issues,systematic research was carried out in Natatorium M in Tianjin,China,so as to study the simulation method for Trihalomethanes?THMs?in natatorium,and assess the THMs health risk for swimmers and staff members.In order to investigate the swimming patterns in natatorium,a survey was conducted where adult amateur swimmers from Tianjin completed 916 self-administered questionnaires.The duration of swimming and dressing were 43.9min/event,and 9.8 min/event,respectively;swimming frequency and monthly duration of swimming were 9.3 event/month and 328 min,respectively.The THMs in water and air in Natatorium M were monitored.The annual average of total THMs in pool water was 303?g/L,0.5 times over the environmental standards;the annual average in pool air was 408?g/m³.In the light of queuing theory,the natatorium random service system was established,which resolved the problem of quantitatively describing the random customer behaviors when modelling.Next,a customer-behaviors-based model for the prediction of THMs in air was proposed,coupled with the three-compartment model and the number of customers computed in random service system.Field monitoring indicated fair accuracy of the model.Furthermore,this model is available for the modelling of contaminants,especially volatile organic chemicals,in water-related public places,and conducive to human health risk assessment.Based on the survey of swimming patterns,field monitoring and modelling results of THMs,carcinogenic risk assessments of staff members and swimmers were conducted,using models recommended by the United States Environmental Protection Agency.The average THMs cancer risk for swimmers in the full cycle of swimming activities was 5.86×10^-5,with 14.9%chance exceeding 10^-4.Inhalation during swimming was the leading exposure route.Assessments of staff members resulted in high occupational health risk,and the risk for the lifeguard ranked first(7.65×10^-4).When the chemical concentrations were close in the main exposure locations,risk in all compartments should be considered and added up,or it would be underestimated.It indicated that some modifications should be made to the framework,so as to ensure the soundness of health risk assessment of swimmers.