CHEMICAL PROFILES|Environmental Protection Agency Risk Assessment Values or Standards

Risk assessment values (RAVs) are numbers that help define the level of health risk posed by a toxic chemical. RAVs are derived from dose-response data obtained from human or animal studies to provide a summary measure of the toxicity of a chemical. Regulatory agencies calculate separate numbers for carcinogens (potencies) and non-carcinogens (reference doses or concentrations). Cancer potencies express how much added cancer risk is associated with lifetime exposure to a unit dose of a chemical (presented as the additional cancer risk associated with an average daily dose of one milligram of a chemical per kilogram of bodyweight). Reference doses and concentrations are estimates of the daily exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects over a lifetime.

Risk assessment values or media quality standards can be used to evaluate the health risks posed by exposures to toxic chemicals. Media quality standards can be compared directly to information about the concentration of a chemical in the environment to identify potential health hazards. If a chemical concentration exceeds a relevant media quality standard, action to reduce environmental contamination or exposure is warranted. Unfortunately, there are relatively few chemicals with standards that define allowable concentrations in air, water, or food. More chemicals have risk assessment values, which can be combined with information about the dose of a chemical that someone receives to characterize health risks. See Scorecard's Guide to Health Risk Assessment for instructions about how to use RAVs to estimate health risks if you have information about chemical exposures.

Scorecard provides all risk assessment values that U.S. EPA has developed and made public in four central toxicity databases: the Integrated Risk Information System, the Health Effects Assessment Summary Tables, the Office of Pesticide Programs Reference Dose and Cancer Potency tracking systems, and the Superfund Chemical Data Matrix; plus several additional sources for specific chemicals. These sources contain all EPA risk assessment values that have undergone sufficient scientific or administrative review to be used in regulatory risk assessments.

More on the availability of RAVs.

The RAVs published on Scorecard have been derived to protect against chronic health effects only and are not appropriate for assessing acute (short-term) exposures.