EPA Targets Cancer-Causing Contaminants
US EPA Administrator Lisa Jackson recently announced plans to strengthen regulations on four known carcinogenic compounds often found in drinking water. With this decision, tetrachloroethylene, trichloroethylene, acrylamide, and epichlorohydrin will face increased scrutiny, and perhaps stricter regulation.
The Safe Drinking Water Act requires the US EPA to review National Primary Drinking Water Regulations (NPDWR) at least once every six years and to make revisions as necessary. In March 2010 administrator Jackson announced the results of the second “six-year” review of national drinking water standards. Of the 71 NPDWR that were reviewed, four were found to be in need of regulatory revision, while the others were deemed to be sufficiently structured. The recommendation to revise the NPDWR starts a regulatory process for increased examination of health effects, costs, benefits, occurrence, and more.
Acrylamide is primarily used in wastewater treatment, paper and pulp processing, and mineral processing. Other uses include as a water-soluble polymer in crude oil production, as a cosmetic additive, for soil and sand stabilization, grouting agents for sewer line sealing and manhole sealing, and in electrophoresis gels used in research. Acrylamide has been detected in a wide range of baked and fried foods. The detection of acrylamide in food prompted intense international interest and on-going research to better characterize its hazard effects, and to modify cooking practices to minimize levels in processed foods.1
Epichlorohydrin has been used in the production of various synthetic materials, including epoxy resins (68% of the epichlorohydrin produced), synthetic glycerin (19%), elastomers (3%), and others (10%) (NCI 1985). It has also been used to cure propylene-base rubbers, as a solvent for cellulose esters and ethers and in resins with high wet-strength for the paper industry (IARC 1999).2
Trichloroethylene or “TCE” is a solvent that has been widely used for vapor degreasing of metal parts. It is also used as an ingredient in adhesives, paint removers, typewriter correction fluid, and spot removers, as an extractant, and as a chemical intermediate. Trichloroethylene has been identified at various levels in the environment, particularly in groundwater. EPA’s Office of Research and Development has developed a draft Integrated Risk Information System (IRIS) toxicological review for TCE and has requested that the SAB conduct a peer review of its assessment.3
The nonfiction book “A Civil Action” by Jonathan Harr describes a case of TCE groundwater contamination in Woburn, MA, which became nationally publicized after it was made into a movie.
Tetrachloroethylene, aka perchloroethylene or “perc,” is widely used for dry-cleaning fabrics and metal degreasing operations. The main effects of tetrachloroethylene in humans are neurological, liver, and kidney effects following acute (short-term) and chronic (long-term) inhalation exposure. Results from epidemiological studies of dry-cleaners occupationally exposed to tetrachloroethylene suggest increased risks for several types of cancer. In the mid-1980s, EPA considered the epidemiological and animal evidence on tetrachloroethylene as intermediate between a probable and possible human carcinogen (Group B/C). The agency is currently reassessing its potential carcinogenicity.3
References
1. US EPA Science Advisory Board: Acrylamide IRIS Assessment
2. NIH National Toxicology Program: Report on Carcinogens, 11th Edition – Epichlorohydrin
3. US EPA Science Advisory Board: Trichloroethylene IRIS Assessment
4. US EPA Air Toxics Website: Tetrachloroethylene (Perchloroethylene)