Health advisory values for drinking water contaminants and the methodology for determining acute exposure values.

The Health Advisory (HA) Program of the Office of Water provides informal technical guidance to Federal, State and local officials responsible for protecting health when emergency spills or contamination situations occur. Under this program, first initiated in 1985, HA values are developed for 1-day, 10-day, longer-term (approx. 7 years) and lifetime exposures based on data describing non- cancer endpoints of toxicity. For substances that are known or probable human carcinogens, lifetime HAs are not recommended. In these situations, the HA document provides an estimate of the drinking water concentration that is equivalent to a l0(-4) 10(-6) cancer risk. US EPA has HA documents for over 175 chemicals dating from 1987 to 1998. A tabular summary of HA values can be accessed through the EPA Office of Science and Technology (OST) web page. The HA support documents provide a concise technical summary of and references for information on chemical, physical and toxicological properties, analytical methods, and treatment technologies. Some of the lifetime HA and cancer values in the HA documents may no longer agree with the most recent Agency assessment for Reference Dose (RfD) and cancer effects. However, the lifetime HA and cancer values presented in the HA tables have been updated to correspond with agency consensus values as presented in the Integrated Risk Information System (IRIS) database.