Pesticides

Overview

Pesticides kill, repel, or control forms of animal and plant life considered to damage or be a nuisance in agriculture and domestic life. Because of widespread use, people are exposed to low levels of pesticides in their food and drinking water, homes, schools, workplaces, and other facilities. Pesticides can get inside the human body from eating, drinking, breathing them in, and through skin contact.

There are several types of pesticides:

• Herbicides destroy or control weeds and other unwanted vegetation. They are commonly used on lawns, golf courses, farms, and landscapes.
• Insecticides kill or control insects. They are used in agriculture, industry, businesses, and households.
• Fungicides control fungi and can be used on plants or other surfaces where mold or mildew grow. They are also used on numerous crops including berries and apples.

Related Health Effects

There are different kinds of pesticides, each of which acts differently, and thus have different health risks. In many cases, the molecular target of a pesticide is shared by non-target species, including humans, leading to the potential for toxicity.

Some effects are rapid and can be severe, even fatal, while other outcomes, such as cancer and Parkinson’s disease, may develop later in life. For example, a dose of paraquat as small as 3 grams (roughly the weight of a penny) can be fatal. Acute exposure to organophosphate pesticides such as chlorpyrifos can result in paralysis, coma, or death, while exposure to lower doses can cause both short and long-term health effects, ranging from nausea and headaches to nervous system problems and respiratory failure.

Research has linked pesticides to a wide range of health conditions. These include risk for Parkinson’s disease, thyroid disease, diabetes, kidney diseases, cancer, rheumatoid arthritis, and shingles (herpes zoster), among other health issues. Evidence suggests that children are particularly susceptible to adverse effects from exposure to pesticides, including neurodevelopmental effects. Many pesticides target the nervous system and are thus neurotoxic by design.

Parkinson’s disease

Some pesticides may contribute to the development and progression of Parkinson’s disease. Several studies, including research from the National Toxicology Program, have identified a link between paraquat exposure and Parkinson’s disease.

Pregnancy and Children’s Health

Many pesticides have long been suspected of being disruptive to thyroid functioning. Disruption of thyroid action during pregnancy can disrupt neurodevelopment in the fetus resulting in cognitive impairment, motor deficits, behavior problems, and greater risk of neurodevelopmental disorders.

Because many pesticides are neurotoxic by design, there is concern that they could harm neurodevelopment. In pesticide applicators and their families, neurological effects including cognitive impairment and features of attention-deficit/hyperactivity disorder (ADHD) have been reported following exposure to insecticides called pyrethroids.

Atrazine can disrupt levels of testosterone and estrogen and induce reproductive dysfunction in both sexes including testicular abnormalities and dysfunction, such as reduced sperm production and viability. Atrazine has also been linked to preterm birth and miscarriage along with later in life risk of breast, prostate, kidney, and ovarian cancer.

Children are more vulnerable and face a higher risk for health problems from harmful environmental factors for several reasons:

• Children eat, drink, and breathe more chemicals than adults relative to their size.
• Children frequently put objects in their mouths and play on the floor and ground.
• Protective bodily systems, such as those that filter pollutants from inhaled air and process chemicals in the body, are not yet fully developed.
• During periods of rapid growth and development, normal biological processes may be disrupted by environmental chemicals.

When pregnant women improved their nutrition and reduced exposure to hazardous chemicals, they were more likely to have healthy babies, and their children were better able to cope with environmental stressors later in life.

Routes of Exposure

Pesticides can enter the body through eating, drinking, breathing them in, and through skin contact.

Farmers have unique work-related exposures to herbicides and insecticides, animals, and dust, as well as risks from operating machinery. Take-home contamination occurs when farmworkers inadvertently take pesticides home on their boots, clothing, and skin. This can introduce a source of exposure to farm workers’ families.

Prevention Guidance

Protective Behaviors include:

• Wearing gloves during work, washing hands, and removing work shoes before entering the home minimize the transfer of pesticides from work clothes to the home. For some applications, use of a respirator may also be recommended along with long sleeves to avoid respiratory and skin exposures.
• Because pesticide residues can be present on foods, selecting organic produce, dairy, and other food products can reduce exposure.
• Water filtration can help remove pesticides from drinking water.

Find Clinical Trials

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Research Information

The National Institutes of Health (NIH) is the largest public funder of biomedical research in the world. NIH invests most of its budget in medical research seeking to enhance life and to reduce illness and disability. NIH-funded research has led to breakthroughs and new treatments helping people live longer, healthier lives, and building the research foundation that drives discovery.

Since 1993, NIH has led the Agricultural Health Study. The study is funded by NIH in collaboration with the U.S. Environmental Protection Agency and the National Institute for Occupational Safety and Health.

Additional NIH-supported research covers:

• Health effects of pesticide exposure
• Effects of pesticides on children’s brain development and respiratory health
• Methods to reduce pesticide exposures
• Interaction of stress and early-life adversity on health in people exposed to chemicals like pesticides
• Environmental factors that contribute to preterm birth

Find NIH-funded research projects using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies.