Overview of Risk Assessment in the Pesticide Program

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 additional information.

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 registration review in the case of a general review of an existing chemical.

On this page:

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.

  • Planning - Planning and scoping process
    EPA begins the process of an ecological risk assessment with planning and research.
  • Phase 1 - Problem formulation 
    Information is gathered to help determine what plants and animals are at risk and need to be protected.
  • Phase 2 - Analysis 
    This is the determination of what plants and animals are exposed and to what degree they are exposed, and whether or not that level of exposure is likely to cause harmful ecological effects.
  • Phase 3 - Risk characterization 
    Risk characterization includes two major components: risk estimation and risk description. "Risk estimation" combines exposure profiles (i.e., the findings of exposure characterization) and effects from exposure. "Risk description" provides information important for interpreting the risk results and identifies a level for harmful effects on the plants and animals of concern.

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:

  • What types of health problems are caused by pesticides in the environment?
  • What is the chance that people will experience problems when exposed to different levels of pesticides?
  • Is there a low level below which some chemicals don’t pose a human health risk?
  • What pesticides are people exposed to and for how long?
  • Are legal limits for pesticide residues in food (tolerances or maximum residue limits) protective of human health?
  • Are people more likely to be susceptible or exposed to pesticides because of factors such as age, genetics, pre-existing health conditions, ethnic practices, gender, where they work, where they play, what they eat, etc.

EPA uses the National Research Council’s four-step process for its human health risk assessments:

  • Step 1 - Hazard Identification
    Examines whether a substance has the potential to cause harm to humans and/or ecological systems, and if so, under what circumstances.
  • Step 2 - Dose Response Assessment
    Examines the numerical relationship between exposure and effects.
  • Step 3 - Exposure Assessment
    Examines what is known about the frequency, timing, and levels of contact with a substance.
  • Step 4 - Risk Characterization
    Examines how well the data support conclusions about the nature and extent of the risk from exposure to pesticides.

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. Read more about cumulative risk assessment.

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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 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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