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Risk Assessment of DBPs and other Contaminants in Drinking Water of Taiwan
risk assessment,trihalomethanes,disinfection byproducts,heavy metals,typhoon scenario,
|Publication Year :||2020|
Safe drinking water is essential to our daily life since it is inevitable that people expose to contaminants in drinking water through multiple exposure routes every day. As a result, the main purpose of this study is to investigate the cumulative cancer risks of co-occurring contaminants in drinking water through oral ingestion, inhalation, and dermal absorption exposures in Taiwan. On the other hand, due to the effects of climate change, typhoons and extreme weather events are occurring more frequently in past decades, resulting in much higher concentrations of trihalomethanes (THMs) in the treated water during the typhoon period. Therefore, the second purpose of this study is to elucidate the lifetime cancer risk resulting from exposure to higher concentrations of THMs during typhoon seasons.
The water quality data used in this study were obtained from the database of the Environmental Protection Administration of Taiwan from January 2002 to December 2019 and the analytical results of collected samples from February 2019 to October 2019. Based on the occurrence data and the available cancer potency information, eight metals (arsenic, lead, selenium, chromium, cadmium, barium, antimony, and nickel) and seven disinfection byproducts (chloroform, bromodichloromethane, dibromochloromethane, bromoform, dichloroacetic acid, trichloroacetic acid, and bromate) were chosen for investigation. Based on the United States Environmental Protection Agency (USEPA) risk assessment guidelines and the lifestyles of residents in Taiwan, the equations and the parameters for calculation of risk assessment were simulated using Monte Carlo simulations with Crystal Ball software.
The results of cumulative cancer risks of these fifteen contaminants from drinking water in northern, central, southern, eastern, and offshore islands of Taiwan were all higher than 10-6, the acceptable risk level defined by USEPA. The highest cancer risk of 1.38×10-4 was in drinking water from offshore islands because the total THM concentration was higher than that in the other areas. All of the results of the hazard index in Taiwan were much lower than 1, the negligible hazard level defined by USEPA. Moreover, the increased cancer risk of exposure to THMs in the typhoon scenario was not apparent for the results of lifetime cancer risk because the five days of exposure duration per year is considerably short when compared to our lifetime.
In conclusion, the cumulative cancer risks from exposure to multiple contaminants in drinking water were higher than 10-6 although there were other water contaminants not included in the assessment. These results suggested that risk assessment should concern about the cumulative health impacts of co-occurring contaminants in drinking water. Besides, it is also necessary to prevent the high exposure to THMs in typhoon seasons by controlling the turbidity and natural organic matters in drinking water, which were the precursors of THMs, during the typhoon.
|Appears in Collections:||環境與職業健康科學研究所|
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