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Overview of Risk Assessment in the Pesticide Program

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The process EPA uses for evaluating the potential for health and ecological effects of a pesticide is called risk assessment.  This page provides a brief introduction to the Pesticide Program’s risk assessment program and includes links to other pages where further information is available.

Risk assessment is crucial to the process of making decisions about pesticides, both new and existing.  New pesticides must be evaluated before they can enter the market.  Existing pesticides must be re-evaluated periodically to ensure that they continue to meet the appropriate safety standard. The decision process is part of a risk management process, which is conducted in registration for new pesticide chemicals or new uses of existing chemicals, or reregistration or registration review in the case of a general review of an existing chemical.

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Ecological Risk Assessment

EPA conducts ecological risk assessments to determine what risks are posed by a pesticide and whether changes to the use or proposed use are necessary to protect the environment. Many plant and wildlife species can be found near or in cities, agricultural fields, and recreational areas. Before allowing a pesticide product to be sold on the market, we ensure that the pesticide will not pose any unreasonable risks to plants, wildlife and the environment. We do this by evaluating data submitted in support of registration regarding the potential hazard that a pesticide may present to non-target plants, fish, and wildlife species. In addition, EPA reviews studies available in the open literature.

Ecological risk assessment includes three phases, and is generally conducted following the Guidelines for Ecological Risk Assessment (U.S. EPA, 1998).

For more information on ecological risk assessment in the Pesticide Program see:

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Human Health Risk Assessment

A human health risk assessment is the process to estimate the nature and probability of adverse health effects in humans who may be exposed to chemicals in contaminated environmental media, now or in the future. Human health risk assessments address questions such as:

EPA uses the National Research Council’s four-step process for its Human Health Risk Assessments:

For more information on human health risk assessment in the Pesticide Program, see:

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Assessing Pesticide Cumulative Risk

The Food Quality Protection Act of 1996 required EPA to conduct a new type of risk assessment for pesticides that were found to have a common mechanism of toxicity. A common mechanism of toxicity is identified when two or more chemicals or other substances cause a common toxic effect(s) by the same, or essentially the same, sequence of major biochemical events. This new assessment is called a cumulative risk assessment and is designed to evaluate the risk of a common toxic effect associated with concurrent exposure by all relevant pathways and routes of exposure to a group of chemicals that share a common mechanism of toxicity.

EPA has guidance for performing cumulative risk assessment (PDF) (90 pp, 490k, About PDF) as well as for identifying pesticides chemicals and other substances that have a common mechanism of toxicity (PDF) (14 pp, 76k, About PDF).

EPA has determined that pesticides have four common mechanism groups of toxicity and has performed cumulative risk assessments for these groups. Future assessment will be conducted for any other common mechanism groups identified in the future.

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Models, Databases, and Guidelines

The risk assessment process depends on having appropriate data and using well tested models.  Data required for pesticide registration are found in 40 CFR Part 158.  EPA also has guidelines for how testing is to be conducted, which are harmonized into a single set of guidelines is to minimize variations among the testing procedures that must be performed to meet the data requirements under the Toxic Substances Control Act (TSCA) (15 U.S.C. 2601) and the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) (7 U.S.C. 136 et seq.).

EPA’s test guidelines also are harmonized with those established by the Organisation for Economic Co-operation and Development (OECD). Harmonized test guidelines reduce the burden on chemical producers and conserve scientific resources, including the minimal use of laboratory test animals. They also form a basis for work sharing and cooperation among all OECD countries. EPA accepts data developed based on an OECD test guideline.

For more information on Models, Databases, and Guidelines in the Pesticide Program, see:

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