Corrigendum to "Risk assessment on disinfection by-products of drinking water of different water sources and disinfection processes" (vol 33, pg 219, 2007)

Institute of Geographic Sciences and Natural Resources Research, CAS Beijing 100101, China.
Environment International (Impact Factor: 5.66). 03/2007; 33(2):219-25. DOI: 10.1016/j.envint.2006.09.009
Source: PubMed

ABSTRACT The occurrences of trihalomethanes (THMs) and haloacetics (HAAs) in the water supply in Beijing and Canada were investigated. The concentrations of THMs and HAAs in Beijing and Canada were below the maximum contaminant levels specified by the USEPA and WHO standards. The multi-pathway risk assessment (assessed through oral ingestion, dermal absorption and inhalation exposure to drinking water) was used to assess the cancer risk and the hazard index of THMs and HAAs from fifteen waterworks in Beijing, China and three treatment plants using different disinfection processes in Canada. Residents in Beijing and residents who were served by three treatment plants using different disinfection processes in Canada had a higher risk of cancer through oral ingestion than through the other two pathways. The cancer risk resulted from disinfection by-products (DBPs) was 8.50E-05(for males), 9.25E-05(for females) in Beijing, China, while it was 1.18E-04, 1.44E-04 in Canada. The risk was higher when water treatment plants used surface water source than when they used ground water source and mixture water source in Beijing. The risk showed different changes in three treatment plants using different disinfection processes in Canada. The lifetime cancer risk for THMs followed the order: Plant 2>Plant 1>Plant 3. And, the lifetime cancer risk for HAAs was: Plant 1>Plant 2>Plant 3.

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Available from: Linsheng Yang, Jul 08, 2015
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    • "In this study, a deterministic approach to human health risk assessment was used based on the United States Environmental Protection Agency guidelines (USEPA 1999, 2002) and recently adopted by many researchers (Lee et al. 2004; Uyak 2006; Wang et al. 2007b). "
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    ABSTRACT: The main objectives of this study were to investigate the concentration and lifetime cancer risk and hazard index of trihalomethanes (THMs) through multiple routes like oral ingestion, dermal absorption, and inhalation exposure in the water samples collected at water treatment plant endpoints. Bromoform has been found in highest concentration followed by chloroform. A lesser concentration of dibromochloromethane has been found than dichlorobromomethane in most of the studied water, which is an unusual scenario, in spite of the high concentration of bromide in the water which can be attributed to the formation, speciation, and distribution of THMs in the breakpoint chlorination curve. Among the three pathways studied, inhalation contributed 80-90% of the total risk followed by oral exposure and dermal contact. Chloroform was found to be the major THM which is having cancer risk in its gaseous form whereas bromoform contributed highest cancer risk through oral ingestion. The average hazard index of total THMs through oral route was higher than unity, indicating high noncarcinogenic risk. The discrepancy between the three exposure pathways may be attributed to different concentration and speciation of THMs present in the waters. The sensitivity analysis by tornado diagram confirmed the highest positive impact of chloroform to the total cancer risk and, indirectly, confirmed inhalation as the major pathway of exposure. This study suggests the modification of the regulatory issues related to THMs based on the health risk associated with each THM and exposure pathway.
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    ABSTRACT: Disinfection of water supplies with chlorine is essential to water treatment, but can lead to the formation of trihalomethanes (THMs) in the presence of natural organic matter. Exposure to THMs via inhalation during daily activities such as showering can significantly increase cancer risks. An innovative decision support system was developed for evaluating THM exposure and risks in water supplies in the Gulf Coast region of Texas by combining a shower THM volatilization model, geospatial analysis techniques, and risk assessment methodologies. Based on THM data from fourteen locations in the region, a power-law equation was developed to predict the formation of THMs in groundwater wells. Health risks associated with THMs in the water supplies of the Gulf Coast of Texas were evaluated. Cancer risks were found to vary from 7.14 9 10 -7 to 7.75 9 10 -6 . While two-thirds of the geographical area was below the threshold risk of 1 9 10 -6 , it accounted for only a tenth of the total popu-lation. Metropolitan areas such as Corpus Christi and McAllen, which currently use surface water sources, and Houston, which is seeking alternate water sources due to subsidence issues, were found to have significant cancer risks (in excess of one in a million). A third of the popu-lation of Texas is housed in the Gulf Coast region, and with more population migration toward the metropolitan areas, it is recommended that water resource management deci-sions be made taking into consideration both the quantity and quality of water available. List of symbols C w THM concentration in cold water (lg/l) C hw THM concentration in heated water (lg/l) C A THM concentration in air (lg/l) C A,avg Average THM concentration in air (lg/l) C A0 Initial THM concentration in air prior to shower (lg/l) k w Growth rate of THM in cold water (min -1) k hw Growth rate of THM in heated water (min -1) E r Absorption efficiency through respiratory system R Air inhalation rate (l/min) t Duration of shower (min/shower) F Shower frequency (showers/day) EF Exposure frequency (days/year) ED Exposure duration (years) BW Body weight (kg) AT Averaging time (days) Q w Flow rate of water into stall (m 3 /min) V Volume of shower stall (m 3) T 1 Temperature of cold water (°C) T 2 Temperature of heated water (°C) k a Air exchange rate between shower and bathroom (min -1) p v THM transfer percentage from water to air phase A s Area of skin exposed to water (m 2) P d Permeability of THMs through skin (m 2 /min) CDI Chronic daily intake (mg/(kg d)) RfD Reference dose (mg/(kg d)) SF Slope factor (kg d/mg) HI Hazard index
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