An official website of the United States government.

We've made some changes to EPA.gov. If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

Pesticide Registration

Understanding the Science behind EPA’s Pesticide Decisions

Science is the backbone of the EPA’s decision-making. The Agency’s ability to pursue its mission to protect human health and the environment depends upon the integrity and quality of the science on which it relies. The environmental policies, decisions, guidance, and regulations that impact the lives of all Americans must be grounded, at a most fundamental level, in sound, high quality science.

The EPA regulates pesticides to ensure that they do not pose unreasonable risks to human health or the environment. As part of that effort, the EPA requires extensive test data from pesticide producers that demonstrate pesticide products can be used without causing harm to human health and the environment.  

We evaluate information from all kinds of sources – pesticide companies, other governments, academia, and the published scientific literature. EPA scientists and analysts carefully review these data to determine whether to register (license) a pesticide product or use and whether specific restrictions are necessary. EPA maintains a transparent, public process for assessing potential risks to human health when evaluating pesticide products.

On this page:


Risk Assessment Process

The process EPA uses for evaluating the potential for health and ecological effects of a pesticide is referred to as a risk assessment. The risk assessment is crucial to the overall decision-making process for 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. EPA’s decision-making relies on 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.

There are two main components to the risk assessment:

  • Ecological Risk Assessment
  • Human Health Risk Assessment

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, the EPA ensures that the pesticide will not pose any unreasonable risks to plants, wildlife, and the environment. This is done 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 scientific studies available in the open literature.

Ecological risk assessments include three phases, and are generally conducted following the Guidelines for Ecological Risk Assessment.

Top of Page

Human Health Risk Assessment

A human health risk assessment process estimates the nature and probability of adverse health effects in people who may be exposed to chemicals in the food and water they consume or in the air they breathe; through their work; or as a result of activities that may lead to contact with pesticide residues on treated surfaces now or in the future. 

EPA uses the National Research Council’s process for human health risk assessments:

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

Top of Page

Epidemiology Studies

EPA considers epidemiology studies that are available as part of its human health risk assessment data and actively supports the Agricultural Health Study. EPA reviews the available epidemiological information using a peer reviewed framework with well-accepted evaluation factors that specifically consider links between pesticide exposure and health outcomes.

Epidemiology Framework: EPA developed a framework to incorporate epidemiology into risk assessment as one component of our work in this area. Concepts in the framework are based on peer-reviewed, robust principles and tools, and incorporate improvements based on recommendations from the National Academies’ National Research Council reports on Toxicity Testing in the 21st Century and Advancing Risk Assessment. This methodology was reviewed in 2010 by the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP), an advisory panel of outside experts.

View OPP's Framework for Incorporating Human Epidemiologic & Incident Data in Risk Assessments for Pesticides (PDF). (51 pp, 526 K, About PDF)

EPA is beginning to implement systematic review procedures consistent with the recommendations of EPA’s Integrated Risk Information System (IRIS) workshops, the National Toxicology Program, and others.  As this process proceeds, the EPA anticipates improved transparency of how scientific information across a broad spectrum of scientific disciplines are integrated into our risk assessment and decision-making process.

Top of Page

When EPA Receives New Studies

EPA actively seeks out and considers new studies, and accounts for this information in pesticide regulatory decisions. When compelling data make it clear that regulatory action must be taken, the Agency responds appropriately.

We look closely at every study to determine whether the results are scientifically sound. Our analysis gives greater weight to high quality and well documented studies and those findings confirmed by multiple sources. Ultimately, the Agency looks at all of the studies to decide what the preponderance of evidence shows.

EPA has practices in place and enforcement policies to help ensure that studies represent sound science. Once studies are submitted to the Agency, EPA scientists conduct extensive analysis of the data to ensure that the design of the study is appropriate and that the data are collected and analyzed accurately.

EPA uses its peer-reviewed framework to incorporate additional epidemiological studies into the risk assessment. Additional information on the risk assessment process for pesticides.

EPA guidance on the review of open literature.

Top of Page

Transparency and Scientific Integrity

At the EPA, scientific integrity is closely linked to transparency. The Agency remains committed to transparency in its interactions with all members of the public and has released Agency-wide principles and policies to clarify the importance of scientific integrity:

  • EPA's Scientific Integrity Policy February 2012 builds on the EPA’s long history of scientific safeguards and further ensures that sound science drives Agency decision making.
  • EPA's Principles of Scientific Integrity outlines foundational principles that promote a culture of scientific integrity, public involvement, the use of peer review and Federal Advisory Committees, and the development of Agency scientists. It also establishes a Scientific Integrity Committee to implement the Agency-wide Scientific Integrity policy. 
  • Annual Report on Scientific Integrity: The 2014 Annual Report highlights EPA's scientific integrity successes.

Additional information on EPA’s Scientific Integrity Policies.

Learn about EPA and the Open Government Initiative. 

Top of Page