Toxic Pesticides: Health Harms, Residues, and Farmworker Risks

Toxic pesticides are chemicals used to kill pests that also carry documented risks to human health, and in the United States several of the most contested ones — chlorpyrifos, glyphosate (Roundup), paraquat, atrazine, dicamba, and 1,3-dichloropropene — remain legal even though they are banned or sharply restricted in dozens of other countries. Lawsuits involving these products have produced some of the largest product-liability settlements in American history, and the regulatory status of each continues to shift through court rulings, EPA reviews, and state-level bans.

The gap between the U.S. and the rest of the world is wide. Seventy-two pesticides currently approved for outdoor agricultural use in the U.S. are banned or being phased out in the European Union, 17 are similarly restricted in Brazil, and 11 in China. The EU prohibits pesticides recognized as mutagens, carcinogens, reproductive toxicants, or endocrine disruptors under a precautionary “safety threshold” approach, while the U.S. system weighs economic and social factors alongside health and environmental risk. In the 18 years before 2019, the EPA took only five non-voluntary cancellation actions against agricultural pesticides; most U.S. prohibitions come from voluntary withdrawals by manufacturers.¹

How Pesticides Harm People

Acute Poisoning

Short-term exposure through inhalation, ingestion, or skin contact can cause headaches, nausea, dizziness, skin irritation, and respiratory problems. Severe cases involve seizures, cardiac arrest, and death, particularly with highly toxic substances like aluminum phosphide and certain rodenticides.² Organophosphate poisoning produces a distinct cluster of symptoms — excessive salivation, sweating, vomiting, and muscle weakness — and can be assessed by measuring acetylcholinesterase levels in the blood.³ Because these symptoms overlap with common illnesses like gastroenteritis, acute pesticide poisoning is frequently misdiagnosed.

Chronic Disease

Repeated or prolonged exposure has been linked to Parkinson’s and Alzheimer’s disease, various cancers, endocrine disruption affecting reproductive health, cardiovascular disease, and damage to the liver and kidneys.²³ Chlorpyrifos and paraquat have been specifically associated with an increased risk of Parkinson’s disease, and glyphosate has been linked to non-Hodgkin lymphoma.

Children face heightened vulnerability because of developing organs, higher relative intake of air and food per pound of body weight, and hand-to-mouth behaviors. Prenatal and early childhood exposure has been associated with autism, ADHD, childhood leukemia, and brain tumors.⁴ Research from the University of California has tied prenatal exposure to pesticides such as acephate and bromacil to retinoblastoma, a childhood eye cancer.⁵

The “Inert” Ingredient Problem

A commercial pesticide product is not just its active ingredient. The rest of the bottle, labeled “inert,” can be biologically active and toxic. A systematic review found that 75% of studies comparing active ingredients alone against full formulations showed increased toxicity when inert ingredients were present.⁶ Some glyphosate formulations are 10 to 100 times more acutely toxic to fish than the active ingredient alone, and certain inert ingredients can increase dermal absorption of the active ingredient by three to 30 times.⁷

Despite this, most registration testing is done on the active ingredient in isolation. Medium- and long-term tests for cancer, reproductive harm, or genetic damage almost never use the full commercial formulation. Inert ingredients are not required to be named on product labels, because manufacturers typically claim that information as confidential business data. A 2021 EPA Office of Inspector General report found the agency had failed to implement endocrine-disruption testing for all pesticide chemicals, including both active and inert ingredients.⁶

Chlorpyrifos

Chlorpyrifos is an organophosphate insecticide linked to neurological damage and developmental harm in children. In August 2021, the EPA revoked all food tolerances for the chemical, effectively banning its use on food crops. That decision was vacated by the U.S. Court of Appeals for the Eighth Circuit on November 2, 2023, which ruled the EPA should have considered whether some food uses could safely continue rather than imposing a blanket ban.⁸⁹

As of mid-2026, chlorpyrifos tolerances are back in effect, and the chemical is legally permitted on 11 specific food crops: alfalfa, apple, asparagus, tart cherry, citrus, cotton, peach, soybean, strawberry, sugar beet, and wheat. These 11 uses represent roughly 55% of total agricultural chlorpyrifos use, and the EPA plans to issue an amended proposed interim decision for public comment in 2026.¹⁰ Several states have gone further than federal law and imposed their own restrictions or bans, including California, Hawaii, Maine, Maryland, New York, and Oregon.⁸

Glyphosate (Roundup)

Glyphosate, the active ingredient in Roundup, is at the center of one of the largest product-liability litigations in American history. Plaintiffs allege the herbicide causes non-Hodgkin lymphoma and that Monsanto (now owned by Bayer) failed to warn users. In February 2026, Bayer proposed a $7.25 billion class settlement to resolve current and future claims from people exposed to Roundup who developed the disease.¹¹ The settlement would pay eligible class members between $10,000 and $165,000 based on exposure history and age at diagnosis.¹²

A Missouri court granted preliminary approval in March 2026, with a fairness hearing scheduled for July 9, 2026. Attorneys representing nearly 20,000 potential class members have filed motions to intervene, objecting that the proposed class definition and liability release are too broad. Separately, the U.S. Supreme Court is considering Monsanto v. Durnell, which could determine whether federal pesticide labeling requirements preempt state-level failure-to-warn claims.¹² Bayer maintains that glyphosate-based herbicides are safe and do not cause cancer, and the settlement contains no admission of liability.¹¹

Paraquat

Paraquat, one of the most acutely toxic herbicides still in use, is the subject of thousands of lawsuits alleging it causes Parkinson’s disease. It is banned in more than 40 countries, including the EU, Brazil, and China, but remains registered in the United States.¹ Federal litigation is consolidated in a multidistrict proceeding (MDL No. 3004) in the Southern District of Illinois, where roughly 6,500 to 6,650 cases were pending as of early 2026.¹³ Another 1,600 to 1,800 cases are pending in the Philadelphia Court of Common Pleas.

In April 2025, the parties in the federal MDL announced a settlement framework, and by March 2026 the court approved a Qualified Settlement Fund to disburse payments.¹⁴ Experts estimate individual payouts could range from $20,000 to $1.5 million, though exact terms remain confidential. The first bellwether trial in the Philadelphia litigation settled in January 2026 the night before opening statements. Primary defendants include Syngenta, Chevron, and FMC Corporation.¹³

Atrazine

Atrazine is banned in more than 60 countries and remains the second most widely used pesticide in the U.S., with roughly 70 million pounds applied annually.¹⁵ In 2025, the International Agency for Research on Cancer classified it as “probably carcinogenic to humans,” and research has linked it to birth defects, fertility problems, and endocrine disruption. It is also a persistent drinking water contaminant; the federal legal limit stands at 3 parts per billion, while California has set a stricter standard of 1 ppb.¹⁶ In 2012, Syngenta paid $105 million to settle a lawsuit brought by more than 1,000 Midwestern water providers over the cost of filtering atrazine from their supplies.

The EPA has been in a prolonged registration review of atrazine. In July 2024, the agency updated the concentration level at which the herbicide is expected to harm aquatic plant communities to 9.7 micrograms per liter, and in December 2024 it proposed new mitigation measures to protect endangered species. In May 2026, conservation groups filed formal notice to compel the EPA to establish water-quality criteria for atrazine under the Clean Water Act, a process the agency began in 1999 but has never completed.¹⁵ HHS Secretary Robert F. Kennedy Jr. has publicly called for a ban on the herbicide, and the administration’s “Make American Healthy Again” report highlighted its health harms.

Dicamba

Dicamba is a volatile herbicide used on genetically modified cotton and soybean crops, and its tendency to drift onto neighboring farms has produced years of damage disputes. On February 6, 2026, the EPA issued a two-season registration for over-the-top dicamba application with what it called the “strongest protections in agency history.”¹⁷ The new rules cut the maximum annual application rate in half (from 2.0 to 1.0 pounds per acre), require a volatility reduction agent with every application, and prohibit spraying when temperatures reach 95°F or above.¹⁸ Aerial application remains banned.

Three products received the 2026 registration: Engenia, Stryax (a new Bayer formulation), and Tavium. The registrations expire on February 6, 2028. Some states have added further restrictions; Minnesota, for example, imposes cutoff dates and bans application above 85°F.¹⁹

1,3-Dichloropropene

The soil fumigant 1,3-dichloropropene, marketed as Telone, is banned in 40 countries. California classified it as a carcinogen in 1989, and the EPA labeled it a “likely carcinogen” in 2007.²⁰ Yet in 2024, more than seven million pounds were applied across 43,000 acres in California, and statewide applications increased by nearly 20% despite new regulations.²¹

California’s Department of Pesticide Regulation enacted buffer-zone rules for residential bystanders in January 2024 and for occupational bystanders on January 1, 2026.²² A February 2026 petition filed in Alameda County Superior Court alleges the state’s protective targets are far too lenient, the modeling assumptions about farmworker schedules are inaccurate, and the rules ignore cumulative exposure for workers who both live and work near treated fields.²³

Neonicotinoids

Neonicotinoids are a class of systemic insecticides tied to declining pollinator populations. Five active ingredients dominate the U.S. market: acetamiprid, clothianidin, dinotefuran, imidacloprid, and thiamethoxam.²⁴ Since 2015, the EPA has temporarily halted approval of most new outdoor neonicotinoid uses pending new pollinator data, and in 2020 released proposed interim decisions that included restrictions on application to blooming crops and a proposed cancellation of residential turf spray uses of imidacloprid.

The EU went further. After a 2013 moratorium on three neonicotinoids, EU member states in April 2018 voted to ban clothianidin, imidacloprid, and thiamethoxam on all field crops, permitting use only in permanent greenhouses.²⁵ A 2023 policy shift determined that individual EU countries can no longer legally grant exceptions for pesticides banned at the EU level.²⁶ In California, Assembly Bill 363 took effect on January 1, 2025, restricting the sale and outdoor non-agricultural use of all five neonicotinoids. These products may only be sold by licensed pest control dealers and used by certified commercial applicators for purposes such as treating trees, turf, and ornamental plants.²⁷

Residues in Food and Drinking Water

The EPA sets legal limits, called tolerances, for pesticide residues on food, and the FDA enforces those limits on domestic and imported products.²⁸ The USDA’s Pesticide Data Program independently tests thousands of food samples each year. Its 2024 annual summary, published in January 2026, found that more than 99 percent of the 9,872 samples tested across 19 commodities had pesticide residues below EPA-established benchmarks.²⁹ The program places particular emphasis on commodities heavily consumed by infants and children.³⁰

For drinking water, the EPA sets Maximum Contaminant Levels and health advisories and works with state and tribal governments to limit pesticide runoff from agricultural and residential sources.³¹ Atrazine remains the most persistent concern, and the federal 3 ppb cap is well above the 1 ppb standard California has set for itself.

Farmworkers and the Enforcement Gap

Farmworkers absorb more pesticide exposure than any other population. The EPA’s Agricultural Worker Protection Standard, originally established in 1992 and expanded in 2015, covers roughly 2.5 million workers and mandates safety training, personal protective equipment, restricted entry intervals after applications, and protections against employer retaliation.³² The government estimated the updated standard would prevent more than $64 million annually in health costs.

Enforcement is thin. The EPA delegates inspection authority to state agencies, and between 2015 and 2019 those agencies inspected roughly one percent of the 346,000 agricultural operations using pesticides. Nearly half of inspected farms had violations, yet only 19% of those faced consequences beyond a warning. During the same period, the EPA itself averaged only 13 inspections per year nationwide.³³ There is no comprehensive national system for tracking individual pesticide poisoning incidents. California, which operates a dedicated Pesticide Illness Surveillance Program, confirmed 859 cases of pesticide-related illness across 614 episodes in 2021 alone, with safety violations identified in 58% of those episodes.³⁴

Where the Fight Goes Next

The regulatory direction depends heavily on who holds office. A January 2025 executive order requires federal agencies to eliminate 10 existing regulations for every new one implemented, and EPA Administrator Lee Zeldin announced a review of 31 regulatory actions for potential rollback in March 2025.³⁵ At the same time, the administration’s own health report called out atrazine’s harms, and Kennedy has urged a ban. Environmental and public health groups are pressing through litigation, formal petitions, and public comment periods — on atrazine water-quality criteria, on 1,3-D buffer zones, on the Roundup class release, and on the Supreme Court’s pending preemption question in Monsanto v. Durnell.

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