Setting criteria and MCLGs for contaminants in ambient and drinking water based on carcinogenic effects
- Environmental Protection Agency, Washington, DC (United States). Office of Water
For the protection of human health from contaminants in ambient and drinking water, EPA is required to set the Ambient Water Quality Criteria and Maximum Contaminant Level Goals (MCLGS) for contaminants in ambient and drinking water. The current method has been driven by the cancer effect via ingestion. For ambient water quality, the criteria were published in 1980; the risk (10{sup {minus}5} to 10{sup {minus}7}) for all carcinogens was estimated by the linearized multistage model. The method for setting the MCLGs is based on 1986 EPA Cancer Guidelines. These Cancer Guidelines classify chemicals into alpha-numerical groups. To estimate cancer risk, the practice has been to rely on the default linearized multistage model (LMS) for low-dose extrapolation. The LMS assumes non-threshold and gives a 95% upper bound on risk. Cancer biology has advanced substantially since 1986, EPA is in the midst of revising the existing cancer guidelines. In parallel, EPA`s Office of Water is proposing to revise the methodology for both ambient water quality criteria and MCLG, including cancer. This new approach will provide more narratives with rationale as to whether the agent is likely to be a human carcinogen. Risk assessment will integrate the whole database, including human and animal tumor data, mode of action, genotoxicity, pharmacokinetics, physical/chemical properties, structure-activity relationship and the route and level of exposure on the agent. Also, depending on biological and physical/chemical considerations, either linear, nonlinear or both approaches will be used for low dose extrapolation. Applications of the revised cancer guidelines to ambient water quality criteria and MCLG development will be presented.
- OSTI ID:
- 212038
- Report Number(s):
- CONF-9511137--; ISBN 1-880611-03-1
- Country of Publication:
- United States
- Language:
- English
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