You are here:
Carcinogenicity of Disinfection By-products and Research Needs
Citation:
DEMARINI, D. M. Carcinogenicity of Disinfection By-products and Research Needs. Presented at Environmental Mutagen Society, San Juan, PUERTO RICO, October 18 - 22, 2008.
Impact/Purpose:
This research was initiated because the literature on the mutagenicity and carcinogenicity and occurrence of drinking water had never been reviewed in the 30 years since research in this area started. Evaluating this literature has provided a basis for the Agency to evaluate its current regulations and to consider future research and regulations in this area.
Description:
A review by S.D. Richardson et al. (Mutat. Res. 636:178, 2007) presents the first analysis of the 30-year literature on the genotoxicity, carcinogenicity, and occurrence of 87 disinfection by-products (DBPs) identified in drinking water. Of these, 11 are regulated by the U.S. EPA, and 76 are not. Of the regulated DBPs, 5 (bromodichloromethane, chloroform, dibromoacetic acid, dichloroacetic acid, and bromate) are trans-species carcinogens and exhibit the toxicological features of IARC- or EPA-declared human carcinogens. Interestingly, 2 (chloroacetic acid and chlorite) are negative each in two species, and 1 (bromoacetic acid) has not been tested for carcinogenicity. Of the unregulated DBPs that occur at µg/L levels, 2 are on test (bromodichloroacetic acid and dibromoacetonitrile), and 8 are carcinogenic (bromochloroacetic acid, dbromochloroacetic acid, chlorate, chloroacetaldehyde, acetaldehyde, formaldehyde, MX, and various nitrosamines). The last 4 exhibit some of the toxicological features of human carcinogens. MX is the most potent, followed by bromate. DBPs have been tested for rodent carcinogenicity by inhalation, drinking water, or gavage, but not by dermal exposure. No DPBs produce bladder or colorectal cancer in rodents, which are the types associated with drinking water in humans. Dermal/inhalation exposure studies in rodents with selected DBPs are needed, considering the emerging evidence that this route is associated with the bladder cancer in humans exposed to drinking water.