Summary

Pursuant to a congressional request, GAO reviewed the Environmental Protection Agency's (EPA) data collection procedures and practices for toxic emissions and hazardous substances, specifically: (1) the types of data that EPA collects to support its regulatory decisions; and (2) EPA verification efforts to ensure the accuracy and reliability of the data it collects.

GAO found that: (1) EPA makes decisions on the extent to which data are collected on an individual chemical or substance basis and, to a large degree, bases decisions on the judgment of its staff; (2) although EPA has broad authority to obtain data it deems necessary to help identify and regulate chemicals manufactured in the United States, it generally does not attempt to obtain data on every individual hazardous substance; (3) to a large extent, EPA relies on available sources, such as published literature and state files, to provide the data it needs; (4) EPA only verifies data to a limited extent to ensure that it is accurate; (5) EPA focuses its efforts on those chemicals for which it has the greatest need for current information and those under regulation or being considered for regulation; and (6) the extent of EPA verification efforts varies depending on where data are obtained and for what purposes. GAO also found that: (1) EPA does not verify data obtained from literature searches and other available sources because it believes that the sources are reliable and accurate enough to identify and screen substances for assessment; (2) once substances are identified as potentially hazardous, EPA reviews the data for reasonableness and completeness; and (3) EPA may also conduct a limited number of on-site emission tests to obtain additional data, but these tests depend on the tradeoffs between costs and benefits.