Pesticide Regulation

Public Notification 

Research Needs 

Research that builds an evidence-base for improving public notification in advance of pesticide applications as a public health intervention, such as: 

• Research utilizing California’s Spray Days notification system to advance understanding of the health impacts of environmental pesticide applications 
• Research on how to utilize existing, publicly available data (e.g. field locations, crops grown, etc.) to provide stakeholders with a more precise estimated location for pesticide applications than the state notification system is currently able to provide 
• Research on the health impacts of pesticides that are not currently restricted in California (which in some cases are banned in other states or countries)   
• Research on impacts of pesticide drift (typically from fumigants) on public health 
• Research that examines the public health impacts of providing advance public notifications of pesticide applications 
• Research on the effective risk mitigation strategies that individuals can take when pesticide applications are planned nearby 

Background & Policy Context 

In 2018, as part of the state’s effort to reduce air pollution in heavily impacted communities, California AB 617 established community steering committees in 10 locations across the state - including one in Shafter - charged with developing Community Emission Reduction Plans (CERPs). The 2019 Shafter CERP included a commitment from DPR to work with the Air District, California Air Resources Board (CARB), and the Kern County Agricultural Commissioner (CAC) to explore options for a public, advance notification system for pesticide applications in the Shafter area. 

[Note: As of 2025, there are 19 Community Air Protection Communities across the state, including several working on pesticide-related issues, including Arvin-Lamont; Eastern Coachella Valley; Westmorland, Brawley, and Calipatria, and Calexico, El Centro, Heber.] 

Pre-application notifications, known as NOIs (Notices of Intent) are reported to County Agriculture Commissioners and, in some counties (including Kern), are also shared with other farmers. In 2021, it was expected that NOIs for applications in Shafter would be made public, and an EHSC Pilot Project was funded to utilize them to develop an app to provide rural communities with effective advance notifications of pesticide applications. However, the Kern County agricultural commissioner did not agree with DPR’s interpretation that his office had to provide these notices to the public under the terms of the CERP. 

In part as a result of the inability to implement a notification system in Shafter through AB 617, the state allocated $10 million in the 2021-22 California state budget to develop and implement a statewide Pesticide Notification Network. DPR conducted four small notification pilot programs in 2022, two of which the EHSC pilot team participated in. The pilots were evaluated in a separate report by the UCD Center for Regional Change (results published May 2023). 

DPR’s statewide notification system, “Spray Days California,” was released in March of 2025 and incorporated many of the components community stakeholders had advocated for. It was updated to include additional community-requested features in August 2025, including the ability to see planned pesticide applications over the previous four days (in addition to upcoming planned applications) and to subscribe to alerts based on square-mile sections on a map, rather than by providing an address.  

One notable feature that rural community groups have asked for throughout the development process that has not yet been adopted is the ability to see precise application locations. While growers do provide these locations to County Agricultural Commissioners in their NOIs, there is currently a lack of standardization in how those locations are formatted (i.e. address, field number, GPS coordinates).  As a result, Spray Days currently uses Public Land Survey System (PLSS) sections as the unit of notification, which identifies the square mile within which an application will take place. This is the same unit used in DPR’s pesticide use reporting system. Community members living and working in agricultural areas have raised concerns that while PLSS sections may be appropriate in the context of state and county level pesticide use reporting, they are too imprecise to enable individuals to take appropriate health-protective actions prior to applications, such as closing windows or moving children inside to play. 

Additional Resources  

• Letter to Governor: Dear Governor Newsom: Pesticides are Air Contaminants too! (2019) 
• The Fresno Bee: California launches 1st online system to notify public of pesticide applications (2025)  

1,3-Dichloropropene (Telone) 

1,3-dichloropropene (1,3-D; Telone) is a fumigant pesticide used as a preplant treatment to control insects, nematodes, and other organisms in a range of crops including nuts, berries, and grapes. It is a Prop 65-listed carcinogen, a Volatile Organic Compound, and a Toxic Air Contaminant. It is the 3rd most heavily used pesticide in California by weight. It is banned in 40 countries. For the last several years, California has been attempting to develop more health protective regulations for the use of 1,3-D in California. This process is nearing completion, but rural community groups have raised concerns that the final rule is insufficient to protect public health, particularly the health of agricultural workers.  

Research Needs 

• Research on 1,3-D drift dynamics to better understand the relationship between applications, exposures, and human health outcomes (see DPR investigation of 2018 1,3-D detections in Shafter) 
• Follow-up to a 2019 UC Merced study (using data from 2005-2011) examining the association between the use of 1,3-D and asthma emergency department visits in California. 
• Research into effective, evidence-based pesticide monitoring strategies with a public health focus (including but not limited to 1,3-D) 
• Research that identifies safe alternatives to fumigant pesticides, for example, by examining agricultural practices and health outcomes in countries where 1,3-D is banned

Background & Policy Context 

The California Department of Pesticide Regulation (DPR ) issued a draft regulation for residential bystanders in November 2022 following a 2018 court judgment and subsequent appeals process. In March 2023, the court determined that the draft regulation failed to comply with the court order, and ordered DPR to work jointly with the Office of Environmental Health Hazard Assessment (OEHHA) to develop a separate regulation for occupational bystanders (i.e. agricultural workers). This is significant because DPR's target lifetime cancer risk level of 0.56 ppb is 14 times higher than OEHHA's No Significant Risk Level of 3.7 micrograms per day (the equivalent of an average annual concentration of 0.04 ppb). In December 2023, OEHHA released recommendations to mitigate the cancer risk to agricultural workers from 1,3-D, which were updated in June 2024. OEHHA’s target level of an average concentration of 0.21 ppb or less over the work life was integrated into DPR’s Risk Management Directive for 1,3-D released in March 2024, which stated that additional control measures would be necessary to reduce exposures to this level. 

In November 2024, DPR released its proposed draft 1,3-D regulation DPR 24-001 to mitigate the potential 40-year working lifetime cancer risk to occupational bystanders. DPR held public hearings in January 2025 to receive public comments, then issued limited regulatory revisions in June 2025, followed by a 15-day comment period. DPR and OEHHA are on schedule to submit the final package to the Office of Administrative Law by November 2025. 

Rural community groups have raised serious concerns with the soon-to-be finalized draft regulation, noting that it has failed to address numerous technical issues that were flagged during the public comment period. These include: 

Estimating exposure based solely on working hours: The draft regulation only addresses worker exposure during work hours, not taking into account the potential for exposures before or after shifts, on non-workdays, and across the lifespan (including during childhood and retirement). 

Inaccurate assumptions about farmworker schedules: The draft regulation assumes fieldwork occurs between 8 am and 4 pm, which does not reflect the common practice of working early mornings or nights to avoid heat, or that fumigants like 1,3-D are also often applied during these cooler hours to minimize drift. As a result, DPR’s modeling may miss periods of peak exposure. 

Low breathing rate that does not reflect conditions of manual labor: The breathing rate used to calculate acceptable air concentration likely underestimates exposure, as it is lower than OEHHA’s risk assessment guidance for moderately intensive labor. 

Model failure at high concentrations: When tested against real-world air data from 2011–2017, the model consistently underestimates higher concentrations.  

Reliance on outdated monitoring data: The current draft regulation relies on air monitoring data that has since been revised by the California Department of Food and Agriculture (CDFA), showing prior estimates undercounted 1,3-D levels by 12–58%

Additional Resources 

• Californians for Pesticide Reform Homepage 
• California Department of Pesticide Regulation Report on Elevated Telone Detections (2018) 
• California Department of Pesticide Regulation Memo: Risk Management Directive for Occupational Bystander Cancer Risk from1,3-D 
• Californians for Pesticide Reform: Open Letter to Department of Pesticide Regulation Director Julie Henderson (April 22, 2024) 
• Californians for Pesticide Reform: Open Letter to Department of Pesticide Regulation Director Julie Henderso

Alternatives to Hazardous Pesticides 

In January 2023, DPR, CalEPA and CDFA released the Sustainable Pest Management (SPM) Roadmap, California’s long-term plan to a) eliminate the use of Priority Pesticides by 2050 by transitioning to sustainable pest management practices, and b) make sustainable pest management the de facto pest management system in California by 2050. As hazardous pesticides are phased out, agricultural communities want to ensure that alternatives are not introduced without comprehensive safety evaluation. 

Research Needs 

Research that provides communities and advocacy groups with accurate information on the human health impacts of proposed alternatives to hazardous pesticides, such as: 

• Research on the human health impacts of classes of pesticides rather than of individual pesticides (e.g. organophosphates rather than just chlorpyrifos). A broader approach can help avoid situations in which the use of a specific product is limited or discontinued and similarly hazardous alternatives continue to be used in its place. 
• Research on the public health costs associated with hazardous pesticide use, including medical care, lost wages/productivity, and educational and other support needs resulting from developmental, cognitive, and motor function impacts. 
• Research comparing public health outcomes in communities in proximity to farms using organic versus conventional pest management practices. 
• Research around the potential harms or health impacts of novelty issues in the pesticide field, including PFAS pesticides, the use of microplastics in pesticide encapsulation (microencapsulated pesticide formulations), gene silencing RNA interference (RNAi) in pest control (a technique that “silences” essential genes in target pests using double-stranded RNA) and genetic biocontrol technologies (such as genetically engineering insects). 

Background & Policy Context 

In response to the 2019 California state ban on chlorpyrifos that went into effect in January 2021, the Department of Pesticide Regulation convened an Alternatives to Chlorpyrifos Work Group and released a list of alternative pesticides in a 2020 Action Plan. A Sustainable Pest Management Work Group was then convened in spring 2021 as a collaborative forum to help identify ways to minimize the use of hazardous pesticides and expand the use of integrated pest management practices. This group’s report, Accelerating Sustainable Pest Management: A Roadmap for California, was released by DPR in 2023. 

Neonicotinoids 

Neonicotinoid insecticides (also known as “neonics”) are a class of widely used neurotoxic insecticides. In addition to agricultural use, they are also widely used in veterinary medicine and commercial and residential pest control. 

Neonics were originally introduced as a lower risk alternative to previous generations of pesticides, but quickly became known for causing significant harm to pollinators and other beneficial insects. Evidence of risk to non-insect animals including humans is emerging, and their most common use (as seed coatings) is not regulated as a pesticide at the federal level due to the novel application method. California passed a law banning non-agricultural uses of neonics that went into effect in 2025, and also agreed as part of a lawsuit settlement to develop a process to regulate coated seeds as pesticides by 2027. 

Research Needs 

Research that characterizes the distribution, concentration, and health impacts of neonicotinoid exposure, such as: 

• Research on the human health risks of exposure to neonicotinoid insecticides 
• Research on neonicotinoid levels in surface, ground, and drinking water in California 
• Research on the specific contribution of neonicotinoid seed coatings to environmental levels 
• Research on neonicotinoid levels in human biosamples 

Background 

Neonicotinoids (often abbreviated “neonics”) are a class of neurotoxic insecticides that act as agonists to nicotinic acetylcholine receptors (nAChRs), which are present in both insects and mammals. Neonicotinoids (imidacloprid, acetamiprid, dinotefuran, thiamethoxam, and clothianidin) are some of the most widely used insecticides in the world, with agricultural, veterinary, commercial, and residential applications. 

Neonics were introduced in the 1990s as a lower-risk alternative to previous generations of insecticides. However, they quickly became known for their negative impacts on pollinators, which led to them being banned in the EU in 2018. Studies have also shown harm from neonic exposure to additional non-target insects, aquatic invertebrates, birds, mammals, and humans. 

Neonicotinoids are water soluble, mobile, and persistent in the environment, particularly in the absence of light (e.g. groundwater, soils) and have been detected in both surface and groundwater in California. 

In 2019, the CDC’s national biomonitoring program concluded that approximately half (49.1%) of the U.S. general population over 3 years old had been recently exposed to neonicotinoids in 2016, with young children (ages 3-5) and those of Asian descent showing the highest levels in their urine. Another more recent study (based on 2017-2021 data) detected neonicotinoids in the blood of 96% of the pregnant women participants (n=171). At least one study has also detected neonicotinoid metabolites in the urine of newborns. 

Policy Context 

Setting a health protective level of neonicotinoids in groundwater: From 2014 to 2020, the neonicotinoid imidacloprid was detected above the reporting limit of 0.05 ppb in 15 Central Valley wells, with concentrations ranging from 0.051 to 5.97 ppb. This triggered a Legal Agricultural Use (LAU) determination process in 2021, as mandated under the California Pesticide Contamination Protection Act (PCPA), which included one member each from DPR, OEHHA, and the State Water Resources Control Board. 

Outcomes of the LAU process included the following:

1. “Legal” finding: DPR’s Groundwater Protection Program (GWPP) found that the well detections of imidacloprid resulted from legal agriculture use.  
2. “No Pollution” finding: The LAU subcommittee found that the presence of imidacloprid in the groundwaters of the state has not polluted and does not threaten to pollute the state’s groundwaters within the meaning of “pollute” as defined under Food and Agricultural Code section 13142, which is based on DPR’s current human health reference level (HHRL) of 283 ppb. 
3. Recommendation for CA Health and Human Services to set a statewide health-protective level for imidacloprid, as OEHHA determined in their official response to the LAU process that DPR’s current HHRL is based on outdated (2006) data and is not health protective based on more recent studies, calculating instead an appropriate level between 2 and 23 ppb. 

Regulating treated seeds as pesticides: Neonicotinoids are systemic insecticides, meaning they are absorbed into a plant's tissues, making the plant itself toxic to insects. In agricultural settings, they are generally applied either as a soil drench (to be taken up by the plant's roots) or (the vast majority) as a seed coating. Seed coatings, regardless of composition, are not currently regulated as pesticides.  

In 2020, NRDC filed a legal petition demanding that the California Department of Pesticide Regulation treat seed coatings as pesticides when they contain ingredients that would be considered pesticides if applied to crops using any other method, which was settled out of court in late 2024 with DPR agreeing to propose regulations addressing pesticide-treated seeds by February 2, 2026, and to finalize these regulations within the following year. In addition, CA AB 1042 was passed in 2023 which will require accurate labeling of treated seeds, starting in 2027. 

The Center for Food Safety and the Pesticide Action Network of North American sued the EPA on similar grounds at the federal level in 2023, however this effort was unsuccessful, with federal court ruling in favor of the EPA in late 2024. 

Banning non-agriculture use of neonicotinoids: Neonicotinoids are widely used in non-agricultural settings, including homes, gardens, and landscaping, as well as in veterinary medicine. In 2022, California passed AB 2146, which would have banned non-agricultural use of neonicotinoids, but was vetoed by the Governor. The bill was reintroduced and passed with some modifications in 2023 as AB 363, and was signed by the governor. It went into effect in January 2025. 

Additional Resources 

• A critical review on the potential impacts of neonicotinoid insecticide use: current knowledge of environmental fate, toxicity, and implications for human health (2020).  
• Bigger than Bees: How Neonics Contaminate Water, Threaten Ecosystems, and Cause Human Health Concerns in New York (2020) 
• NRDC Sues to Close Huge California Pesticide Loophole (2023)