Effects of Pesticides on Human Health

Organophosphate and carbamate pesticides harm the body by inhibiting acetylcholinesterase, which affects the nervous system. Short-term effects are neurological, gastrointestinal, skin and eye, and respiratory, and severe poisoning can follow. Long-term effects include cancer, endocrine disruption, reproductive effects, neurological disorders and respiratory issues. Agricultural workers, applicators and chemical manufacturing workers are most at risk. People take in pesticides through ingestion, dermal absorption, inhalation or the eyes. Doctors diagnose poisoning from an exposure history and the symptom pattern. Prevention starts with adequate protection for the people who spread pesticides, and regulators set use limits before approval.

How Do Pesticides Harm the Human Body?

Organophosphate and carbamate pesticides harm the human body by inhibiting acetylcholinesterase. Acetylcholinesterase inhibition lets acetylcholine accumulate at nerve endings. Inhibition of acetylcholinesterase is the primary mechanism common to all organophosphates. A 1993 study by L J Fuortes from the University of Iowa College of Medicine found irreversible inhibition by organophosphates. Carbamate pesticides produce reversible effects, because the body quickly reverses their action. Carbamate illness is usually less severe and shorter than organophosphate illness. Carbaryl, a methylcarbamate, is an organic compound that Union Carbide discovered and commercialized in 1958. Pesticides enter the human body through contact with the skin and through the mouth, lungs and eyes. Organophosphate poisoning is poisoning due to organophosphates, and it typically follows inhalation, ingestion or dermal contact. WHO states that adverse effects from these pesticides occur only above a certain safe level of exposure. Toxicity depends on the function of the pesticide, and insecticides tend to be more toxic to humans than herbicides. Malathion is a nonsystemic, wide-spectrum organophosphate that requires conversion to malaoxon to become an active anticholinesterase agent.

What Are the Short-Term Effects of Pesticides?

The short-term effects of pesticides are neurological, gastrointestinal, skin and eye, respiratory and severe poisoning effects. Acute pesticide poisoning produces them, and illness may occur quickly or be delayed a few hours. Key types include:

• Neurological effects: Muscle twitches, pupil constriction and weakness mark nerve involvement, and severe poisoning constricts the pupil of the eye.
• Gastrointestinal effects: Nausea, vomiting, stomach cramps and diarrhea appear in mild organophosphate poisoning, with excessive sweating and salivation.
• Skin and eye irritation: Contact with the skin or eyes produces redness, blisters or irritation.
• Respiratory effects: Breathing difficulty and asthma-type symptoms appear, and severe cases bring secretions from the mouth and nose.
• Severe poisoning: Severe poisoning causes unconsciousness and death if untreated.

A 2008 study by Michael Eddleston from the University of Oxford reported case fatality generally above 15% with medical management. Mild poisoning causes fatigue, headache, dizziness and blurred vision. Symptoms that start more than 12 hours after exposure point to some other illness.

Intermediate syndrome shows an unpredictable course, and its neurologic symptoms typically occur 24 to 96 hours after exposure. Unlike acute poisoning, chronic poisoning may stay hidden for weeks, months or even years. Symptoms of poisoning are nonspecific and often misdiagnosed, so acute cases are often missed. Malathion is a slightly toxic compound in EPA toxicity class III.

Do Pesticides Cause Skin and Eye Irritation?

Yes. Pesticides cause skin and eye irritation, and allergic contact dermatitis occurs after repeated chronic exposure. A single exposure usually causes primary irritant dermatitis. Symptoms range from slight redness of the skin to blisters or ulcerated lesions. Allergic contact dermatitis develops when the allergenic substance contacts previously sensitized skin.

The US Environmental Protection Agency stated in 2026 that some pesticides can irritate the skin or eyes. The severity of the irritation is influenced by the chemical properties of the substance, duration and method of exposure. Pyrethrins and pyrethroids usually cause respiratory concerns and irritation to the skin and eyes.

Of 45 reports of dermatitis, 22 were confirmed to be allergic contact dermatitis due to pesticide exposure. Regulators test skin irritation and corrosion with the rabbit Draize test, which many agencies require.

What Are the Long-Term Health Effects of Pesticides?

The long-term health effects of pesticides include cancer, endocrine disruption, reproductive effects, neurological disorders and respiratory issues. Chronic pesticide poisoning produces them, and its symptoms may not become evident for weeks, months or even years. Key types include:

• Cancer: Oncogenicity and carcinogenicity are listed effects of chronic pesticide poisoning, and some pesticides are carcinogens.
• Endocrine disruption: Many pesticides act as endocrine disruptors that affect the hormone system.
• Reproductive effects: Chronic pesticide poisoning includes reproductive effects, such as decreased sperm count and infertility.
• Neurological disorders: Neurotoxicity is a listed effect of chronic poisoning, and many pesticides are neurotoxic.
• Respiratory issues: Respiratory issues were often associated with occupational exposure to pesticides.

A 2024 systematic review by Chander Shekhar in Toxicology reports found consistent links between chronic pesticide exposure and non-communicable diseases. Those diseases include cancer, neurological disorders and endocrine disruptions. Prolonged or high intensity exposure, particularly among agricultural workers, made long-term health effects more likely. Several factors limit definitive conclusions, including variations in pesticide types, exposure levels and health outcomes. Additional research is necessary to elucidate dose-response relationships and mechanisms of action.

The Agricultural Health Study is a prospective cohort of licensed pesticide applicators and their spouses from Iowa and North Carolina. It tracks cancer and other health outcomes. Dieldrin and aldrin are two structurally similar compounds that were once used as insecticides.

Can Pesticides Cause Cancer?

It depends. Some pesticides can cause cancer, but the risk depends on the exposure level and the pesticide. WHO states that none of the pesticides currently authorized for use on food in international trade are genotoxic. Adverse effects from authorized food pesticides occur only above a certain safe level of exposure.

A 2019 meta-analysis by Luoping Zhang from the University of California Berkeley linked glyphosate-based herbicide exposure to non-Hodgkin lymphoma. Growing evidence indicates that exposure to organochlorine pesticides could increase non-Hodgkin lymphoma risk. A 2016 meta-analysis by Zhen Liang in Oncotarget associated pesticide exposure with an increased risk of bladder cancer.

Chander Shekhar from the Central University of Himachal Pradesh Shahpur Campus identified consistent associations between chronic pesticide exposure and cancer. Applicators exposed to high levels of pesticides over many years run the greatest risk of developing chronic effects. EPA evaluates pesticides for potential carcinogenicity, and some pesticides may be carcinogens.

Glyphosate has a regulatory consensus: national pesticide regulatory agencies judge labeled uses unlikely to be carcinogenic to humans. The European Food Safety Authority peer reviewed the initial glyphosate risk assessments. France, the Netherlands, Sweden and Hungary carried them out. A conclusion by the International Agency for Research on Cancer triggered a reconsideration of carcinogenicity evidence in the EU. The Joint Meeting on Pesticide Residues is an expert ad hoc body administered by FAO and WHO. That body later reconsidered the evidence.

Do Pesticides Disrupt Hormones?

It depends. Some pesticides disrupt hormones by affecting the endocrine system, and the human evidence is strongest for organophosphates. Many pesticides act as endocrine disruptors and are associated with diabetes mellitus and reproductive disorders.

A 2020 study by Linda G Kahn from New York University linked organophosphate pesticides to reduced semen quality. Endocrine disruptions are among the consistent associations with chronic pesticide exposure. More research is needed on dose-response relationships and mechanisms of action.

Following a 1996 amendment, EPA established the Endocrine Disruptor Screening Program to study estrogen, androgen and thyroid effects of pesticides. Before approving a pesticide, EPA sets limits on how the pesticide may be used.

Do Pesticides Affect Reproduction?

Yes. Pesticide reproductive harm includes birth defects, stillbirth, spontaneous abortion, sterility and infertility. Pesticides affect reproduction as part of chronic poisoning, whose effects include reproductive effects. Reproductive disorders linked to pesticides in men include decreased sperm count.

A 2004 study by Sunil Kumar in the Journal of occupational health reported adverse male reproductive outcomes. Occupations involving the manufacture or application of persistent chemicals are associated with reproductive dysfunction.

Symptoms of aldrin and dieldrin poisoning have been seen in people exposed to very large amounts during manufacture. Workers involved in the manufacture of chemicals are at the greatest risk of chronic effects.

In 1962, Rachel Carson noted in Silent Spring that DDT bioaccumulates and biomagnifies up the food chain. The Center for the Health Assessment of Mothers and Children of Salinas runs the CHAMACOS study. CHAMACOS is the longest running longitudinal birth cohort study of pesticides among children in a farmworker community.

Do Pesticides Affect the Lungs?

It depends. Pesticides affect the lungs mainly in occupational settings, and systematic reviews associate exposure with asthma. A history of high pesticide exposure was associated with a doubling of asthma risk.

A 2014 study by Emma Doust from the University of Birmingham linked pesticide exposure to prevalent asthma. Methodological issues limit the evidence base, including exposure measurements and limited adjustment for confounders. Pyrethrins and pyrethroids usually cause respiratory concerns, for example asthma.

Chronic obstructive pulmonary disease carried a 13% increased risk after workplace exposure to pesticides at any point. Occupational exposure is the setting most associated with respiratory issues.

The Agricultural Health Study began in 1993 to study how agricultural, lifestyle and genetic factors affect farming populations.

Do Pesticides Cause Neurological Disease?

Yes. Organophosphates and carbamates affect the nervous system by inhibiting acetylcholinesterase. Pesticides cause neurological disease, because many pesticides and virtually all insecticides are neurotoxic. Parkinson’s disease is strongly associated with chronic exposure to chlorpyrifos and paraquat.

A 2019 meta-analysis by Wimonchat Tangamornsuksan from Naresuan University linked paraquat exposure to Parkinson’s disease. Environmental Health Perspectives stated in 2011 that exposure to herbicides and insecticides increases the risk of Parkinson’s disease.

Late neurological sequelae may appear two or more weeks following exposure, even when early neurologic function returns to normal. They include peripheral neuropathy and Parkinson-like symptoms.

Paraquat exposure over many years might lead to central nervous system toxicity in observational human studies and animal experiments. Agricultural workers are more likely to experience long-term health effects. Chlorpyrifos is an organophosphate insecticide that EPA evaluated with diazinon and malathion for risks to threatened and endangered species. Amyotrophic lateral sclerosis is another neurological disease where evidence suggests occupational pesticide exposure may increase the risk. Neurotoxic mechanisms activated by low-dose chronic exposure may not be associated with acetylcholinesterase inhibition.

Who Is Most at Risk From Pesticides?

The people most at risk from pesticides are agricultural workers who apply pesticides, applicators and chemical manufacturing workers. Children come next, followed by people in the immediate area during and after spraying. The rank follows the directness and length of exposure.

Children under 10 account for at least 50 percent of accidental pesticide deaths in the United States. Children are at the highest risk of accidental ingestion. Pesticides threaten children more because their exposure is greater in proportion to their body mass. Twenty years of CHAMACOS data and nearly 300,000 biological samples describe children’s development in a Latino farmworker community.

Chander Shekhar from the Department of Animal Sciences linked prolonged or high intensity exposure to long-term effects in agricultural workers. Applicators who handle high levels of pesticides over many years face the greatest risk of chronic effects.

Paraquat is not registered for home use. The highest exposures fall on people who manufacture or apply it, or live near farms.

How Do People Get Exposed to Pesticides?

To get exposed to pesticides, people take in the chemical through ingestion, dermal absorption, inhalation or absorption through the eyes. Most pesticide exposure comes through unrecognized inhalation, skin contact or ingestion, the Massachusetts Medical Society stated in 2022. Applying chemicals in enclosed areas, such as grain bins and barns, may expose a person to higher levels. Accidental ingestion usually happens when pesticides move from the original labeled container into an unlabeled bottle or food container.

The general population is exposed to significantly lower levels of pesticide residues through food and water. The National Health and Nutrition Examination Survey measures urinary metabolites of organophosphate pesticides. Researchers tested whether levels declined between NHANES III and NHANES 1999 to 2004.

Plasma cholinesterase adducts serve as biomarkers of pesticide exposure, because organophosphorus and carbamate pesticides bind the active site of butyrylcholinesterase.

Do Pesticide Residues Stay in Food?

Yes. Pesticide residues stay in food, and some residues linger for several months. Governments set maximum residue limits for pesticides in food from acceptable daily intakes. Consumers can limit their intake by peeling or washing fruit and vegetables.

A 2021 study by Anastasia Konstantina Sakali in Nutrients found residues largely in daily consumed food. Extensive use in farming and a long half-life explain this.

The Codex Alimentarius Commission is the intergovernmental body that sets food standards. WHO and FAO set limits that people can safely consume over a lifetime. EPA relies on Pesticide Data Program data for dietary risk assessments. The program ensures residues in foods remain at or below the levels EPA has set.

The Environmental Working Group ranks pesticide residues on fruits and vegetables in an annual Dirty Dozen list. It gives no context on what amounts regulatory agencies consider safe. EU Member States analysed 6,761 food samples for glyphosate residues in 2016.

How Are Pesticide Poisonings Diagnosed and Treated?

To get pesticide poisonings diagnosed and treated, start with an exposure history and check for the pesticide symptom pattern. With the exception of the organophosphates, diagnosis of pesticide poisoning is primarily clinical, due to a lack of diagnostic tests. Remove all contaminated clothing and wash contaminated skin with water. Call a physician or take the exposed person to a hospital without delay, and bring the pesticide container or label. Give supportive care, because rapid treatment within minutes prevents hypoxic brain damage and improves long term prognosis. Use oximes and atropine for organophosphate poisoning, the recognized antidotes. No specific treatment exists for any other pesticide exposure other than supportive care.

A 2024 study by Shafeajafar Zoofaghari in Advanced biomedical research reports that organophosphate diagnosis rests chiefly on clinical evidence.

Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings. Pralidoxime is the most often used oxime worldwide. Plasma cholinesterase testing identified the pesticide in 4 patients with 60 to 84 percent butyrylcholinesterase inhibition. It missed the pesticide in 2 patients with 8 and 22 percent inhibition.

How Can Pesticide Exposure Be Prevented?

To have pesticide exposure prevented, start with adequate protection for people spreading pesticides. Bystanders stay away from the area while spreading takes place, and for some time afterwards. Wear gloves and face masks as necessary. Avoid pesticides in unventilated or poorly ventilated spaces, and keep pets and children away following application. Before approving a pesticide, EPA sets limits on how it may be used and what protective clothing must be used.

A 2022 workshop report by Martin Röösli found limited evidence regarding which interventions reduce pesticide exposure.

The Federal Insecticide, Fungicide, and Rodenticide Act established examination and certification for applicators of restricted use pesticides. Paraquat dichloride is a restricted-use, broad-spectrum herbicide that controls weeds in agricultural and horticultural crops in the United States. Better education and training of farmers and pesticide handlers may help to reduce asthma risk.

How Do Regulators Limit Pesticide Health Risks?

Regulators limit pesticide health risks by assessing each pesticide and setting use limits before approval. EPA pesticide approval sets limits on use, frequency of use and protective clothing. EPA assesses risks for individual active ingredients and for groups of pesticides with a common toxic effect. This cumulative risk assessment evaluates exposure to multiple pesticides that act the same way in the body. The Joint Meeting on Pesticide Residues bases its assessments on all data submitted for national registrations worldwide. Peer-reviewed scientific studies add to that data. The World Health Organization stated in 2022 that maximum residue limits come from acceptable daily intakes. Codex standards cover more than 100 pesticides. Adverse effects occur only above a certain safe level of exposure. EPA has human health benchmarks for approximately 350 pesticides registered for food crops. The degree of toxicity determines what precautions must appear on the pesticide label, including the signal word. The Globally Harmonized System of Classification and Labelling of Chemicals is an internationally agreed standard managed by the United Nations. Under the Federal Insecticide, Fungicide, and Rodenticide Act, no individual may sell, use or distribute an unregistered pesticide. Atrazine is a chlorinated triazine systemic herbicide that EPA re-evaluates periodically through registration review.