How Pesticides are Evaluated
Our Evaluation Process
All pesticides must be registered with the U.S. Environmental Protection Agency (U.S. EPA) before they can be used. To address California-specific conditions to protect human health and the environment, the California Department of Pesticide Regulation (DPR) evaluates all pesticides before they can be sold or used in California. We also conduct a continuous evaluation process following registration to assess new information on the potential risks and impacts of pesticide use to people and the environment.
Registration Evaluation (Before Registration, Before a Pesticide Can Be Used)
At DPR, we evaluate pesticides before they are eligible for registration. We conduct an extensive review of scientific studies on potential human health and environmental impacts, as well as overall efficacy, before a pesticide is eligible for registration in California.
Risk is a product of pesticide toxicity and organism exposure. To identify potential risks or significant adverse effects, our scientists evaluate submitted data on toxicity and exposure, available literature, and monitoring data to model how a product would behave under California-specific conditions once it has been applied. Registrants can mitigate some identified risks by changing label language. Examples of common mitigation include drift reduction instructions, reduced application amounts, and changes to use patterns such as removing bee attractive crops to protect bees or adding space between an application site and waterbody to protect aquatic species. Products with significant adverse effects that cannot be mitigated during the registration process are not registered for use in California.
How Pesticides Are Registered
Human Health Evaluation
We evaluate the potential risk of pesticide use on human health, including what potential health impacts could occur when pesticides are used, and how to protect humans from potential exposure.
We require registrants to submit data on a product’s potential chronic (long-term), sub-chronic, and acute (short-term) health effects. DPR scientists review the data for compliance with federal and state guidelines, and the highest standards of science in evaluating potential health hazards before making a recommended registration action. The evaluation also reviews the accuracy of pesticide labels first aid statements, and requirements for personal protective equipment (PPE), and restricted entry intervals (REIs) to protect worker health and safety. Products with significant adverse effects that cannot be mitigated during the registration process are not registered for use in California.
More information on the standards DPR uses to evaluate toxicity data to protect human health can be found in the resources below.
Environmental Evaluation
We evaluate the potential risks of pesticide use to nontarget flora (plants), fauna (wildlife), air, and water quality.
Product and Efficacy Evaluation
We evaluate all pesticide products to check that they contain only approved ingredients and will work as described on the product’s label. To do this, our scientists review the ingredients in formulations and information about the overall product.
For active ingredients (the main ingredient that makes a pesticide work), we look at data about the physical or other properties, persistence in the environment, and its ability to move through the environment to assess a pesticide’s risks or impacts. Inert (non-active) ingredients are also reviewed and must be listed on U.S. EPA’s Inert Finder list or U.S. EPA’s Trade Name Database, indicating that they have been reviewed and approved by U.S. EPA.
Performance is not evaluated by U.S. EPA for most products. The review of product claims is, however, an essential step in California, both for evaluating whether a product will function as expected in California when used following the label’s directions and for identifying effective alternatives to high-risk pesticides.
Continuous Evaluation (After a Pesticide is Registered in CA)
After a pesticide is registered, we enter a phase called continuous evaluation. Continuous evaluation addresses new information about pesticide risks and impacts on human health and the environment. Key to this process is ongoing monitoring and human health and environmental assessments of the pesticides used in California.
We collect data on levels of pesticides in the environment, potential exposure patterns, potential adverse impacts on human health or the environment, and how well our mitigation efforts are working to protect human health and the environment.
What is Continuous Evaluation?
What is Included in Continuous Evaluation?
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Analysis
Review and evaluate data and literature, including studies and public submissions of data to help inform our understanding of pesticide risks and impacts.
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Investigation
Investigate reported pesticide illnesses. We track and evaluate all reports to add or improve measures to protect workers and the public.
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Monitoring
Monitor and model pesticides in the air, groundwater, surface water, fresh fruits and vegetables, and within ecosystems. We compare any pesticide detections against health protective or environmentally protective screening levels.
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Assessment
Conduct health assessments of pesticides detected in fresh fruits and vegetables, drinking water, air, cannabis, and for pesticide spill or release incidents, as well as assessments of human health exposure and risk from pesticide use in California.
When a pesticide is newly detected in groundwater from legal agricultural use, we initiate a public process outlined in the Pesticide Contamination Prevention Act. This process leads to a determination by committee of whether continued agricultural use of the pesticide can be allowed and under what conditions.
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Research
Conduct fieldworker exposure studies to model potential sources of exposure to pesticides. We also study the impact of mitigation measures on decreasing potential exposure.
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Tracking
Track the pesticides used in the state through Pesticide Use Reports, which include detailed reporting on the quantity and type of pesticides used in all agricultural and some non-agricultural settings across the State. We look at use rates as part of our studies on risks or impacts.
Continuous Evaluation Actions to Assess Risk?
When we identify a pesticide risk, we can address it through a variety of actions including adoption regulations and required mitigation measures, working with the registrant to change the use requirements on the pesticide label, and conduct training to reduce the potential for exposure.
We may determine that more data is needed to evaluate risks and inform mitigation measures, which could include initiating a risk assessment to quantify risk or determine if mitigation is effective. We can also launch a formal reevaluation to collect additional data to inform department actions.
Our actions to assess risk can include:
Risk Assessments
A human health or ecosystem risk assessment can determine the significance of an adverse impact to inform mitigation actions such as label or use changes, permit conditions, or other regulatory changes. Risk assessments are part of our continuous evaluation as well as the latest scientific research and used to identify or quantify risks.
Reevaluation
The department may initiate a reevaluation as part of continuous evaluation where DPR investigation has identified a pesticide may have caused or is likely to cause a significant adverse impact on people or the environment. It is a formal statutory process that provides us the authority to request registrants to generate new scientific data to better understand and characterize pesticide risks. We evaluate the data and determine if there are ways to reduce or eliminate significant adverse impacts associated with the use of a pesticide. Reevaluations can vary in complexity depending on new data, the number of sites where products are used, the number of products containing that specific active ingredient, and the importance of data gaps. If additional mitigation is needed, DPR is subject to applicable timelines established in AB 2113 or as otherwise provided by law.
AB 2113 (Chapter 60, Statutes of 2024) established the requirement that DPR post on its internet website an estimated completion time for the pesticides that the department has under reevaluation as of January 1, 2024. In accordance with that requirement, DPR is publishing the estimated completion times for all current reevaluations (see “Active Reevaluations” table below). Individual reevaluations with statutorily imposed timelines are also noted below. Scientific assessment is necessary to determine if there are pesticide use scenarios that require mitigation. Under AB 2113, DPR will provide annual updates on its progress, allowing for better resolution on specific timelines.
Active Reevaluations
For each active ingredient currently under reevaluation, the planned stages of the reevaluation with estimated completion dates. More detail for each reevaluation can be found on the Status of Current Actions to Continuously Evaluate Pesticide & Mitigate Risks page.
More Information on Continuous Evaluation
To view current risk assessments, reevaluations and other actions in progress at DPR, visit our Look Up Pesticide Information page.
To learn more about environmental monitoring, pesticide illness surveillance, residue monitoring and other data and reports, visit our Data and Reports Directory.
To view information on pesticides in the process of reevaluation, visit our Registrant Stakeholder Notices and Information page and select the “Reevaluation Semiannual Report” from the drop-down menu.
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Still have a Question or Need More Information?
Please contact us with questions or visit the Contact Us page on our website to connect with other programs at DPR.
Email: cdprweb@cdpr.ca.gov
Phone: (916) 445-4300