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OVERVIEW OF DRINKING WATER MUTAGENICITY AND CARCINOGENICITY AND RISK FOR BLADDER CANCER
Citation:
DEMARINI, D. M. OVERVIEW OF DRINKING WATER MUTAGENICITY AND CARCINOGENICITY AND RISK FOR BLADDER CANCER. Presented at Asian Environmental Mutagen Society Conference, Pattaya, THAILAND, December 15 - 18, 2010.
Impact/Purpose:
This is a review of recent work from our lab and elsewhere that indicates that the brominated THMs in drinking water and pool water are a risk for bladder cancer (especially among a susceptible sub-population) and for genotoxicity (among swimmers).
Description:
Among the 11 disinfection by-products (DBPs) in drinking water that are regulated by the U.S. EPA, (a) 2 DBPs (chloroacetic acid and chlorite) are not carcinogenic-in either of 2 species; (b) chlorite is not carcinogenic in 3 rodent assays and has never been tested for genotoxicity; (c) 1 DBP (bromoacetic acid) has never been tested for carcinogenicity; (d) 2 DBPs, chloroform and trichloroacetic acid, are carcinogenic via nongenotoxic mechanisms; (e) 6 DBPs have significant genotoxicity data gaps; and (f) 5 DBPs have been assessed as possible or probable human carcinogens. Among 74 unregulated DBPs, 29 that occur at <1 ug/L levels are genotoxic; and another 14 that occur at this level have no toxicological data except for 2, which are carcinogenic. The toxicity of halogenated DBPs is iodo > bromo> chloro, and 50% of the organic carbon and organic halogens of drinking water are not yet chemically characterized. A recent case-control bladder cancer study in Spain showed that the 28% of those who used water containing >49 ug/L of the 4 trihalomethanes (THMs) combined and who had a specific genotype (GSTTl + and a SNPin GSTZ) had a 6-fold risk for bladder cancer. Additional studies have found that dermal/inhalation exposure to DBPs via swimming in a chlorinated pool for 40 min produced micronuclei in the blood and mutagenic urine that were associated with the concentration of brominated THMs (not chloroform) in exhaled breath. Collectively, these studies indicate that a sub-population with the "at-risk" genotype and who are exposed to the brominated THMs in disinfected water primarily via the dermal/inhalation routes have the potential for increased risk for bladder cancer. [Abstract does not necessarily reflect the policy of the U.S. EPA.]