Pesticides and human health

Pesticides can cause short-term adverse health effects, called acute effects, as well as chronic adverse effects that can occur months or years after exposure. Examples of acute health effects include stinging eyes, rashes, blisters, blindness, nausea, dizziness, diarrhea and death. Examples of known chronic effects are cancers, birth defects, reproductive harm, neurological and developmental toxicity, immunotoxicity, and disruption of the endocrine system.

Some people are more vulnerable than others to pesticide impacts. For example, infants and young children are known to be more susceptible than adults to the toxic effects of pesticides. Farm workers and pesticide applicators are also more vulnerable because they receive greater exposures.

Acute (Immediate) Health Effects

Immediate health effects from pesticide exposure includes irritation of the nose, throat, and skin causing burning, stinging and itching as well as rashes and blisters. Nausea, dizziness and diarrhea are also common. People with asthma may have very severe reactions to some pesticides, particularly pyrethrin/pyrethroid, organophosphate and carbamate pesticides.

In many cases, symptoms of pesticide poisoning mimic symptoms of colds or the flu. Since pesticide-related illnesses appear similar or identical to other illnesses, pesticide poisonings are often misdiagnosed and under-reported. Immediate symptoms may not be severe enough to prompt an individual to seek medical attention, or a doctor might not even think to ask about pesticide exposure. Still, seek medical attention immediately if you think you may have been poisoned by pesticides.

Chronic (Long-term) Health Effects

Chronic health effects include cancer and other tumors; brain and nervous system damage; birth defects; infertility and other reproductive problems; and damage to the liver, kidneys, lungs and other body organs. Chronic effects may not appear for weeks, months or even years after exposure, making it difficult to link health impacts to pesticides.

Pesticides have been implicated in human studies of leukemia, lymphoma and cancers of the brain, breasts, prostate, testis and ovaries. Reproductive harm from pesticides includes birth defects, still birth, spontaneous abortion, sterility and infertility.

Endocrine disruptors are chemicals that — often at extremely low doses — interfere with important bodily functions by mimicking or blocking hormones (the chemical messengers that circulate in blood and regulate many body processes including metabolism, brain development, the sleep cycle and stress response). Some pesticides act as endocrine disruptors and have been shown to cause serious harm to animals, including cancer, sterility and developmental problems. Similar impacts have been associated with human exposure to these chemicals.

Children are More Vulnerable to Pesticide Exposure

Children are not simply “little adults.” Children are more vulnerable to pesticides exposure because their organs, nervous systems and immune systems are still developing; their higher rates of cell division and lower body weight also increase children’s susceptibility to pesticide exposure and risks. Their immature organs and other developing biological systems are particularly vulnerable to toxic contaminants. Exposure during certain early development periods can cause permanent damage.

In addition to being more vulnerable to pesticide toxicity, children’s behavior and physiology make them more likely to receive greater pesticide exposure than adults. Most pesticide exposure occurs through the skin and children have more skin surface for their size than adults. Children have a higher respiratory rate and so inhale airborne pesticides at a faster rate than adults. Children also consume proportionately more food and water — and pesticide residues — than adults. With their increased contact with floors, lawns and playgrounds, children’s behavior also increases their exposure to pesticides.

Health Effects of Certain Classes of Pesticides

Organophosphates & Carbamates: These pesticides are like nerve gas: they attack the brain and nervous system, interfering with nerve signal transmission. Symptoms include headaches, nausea, dizziness, vomiting, chest pain, diarrhea, muscle pain and confusion. In severe poisoning incidents, symptoms can include convulsions, difficulty breathing, involuntary urination, coma and death. Acute poisoning of the nervous system by these pesticides affects hundreds of thousands of people around the world each year.

Fumigants: Fumigants like methyl bromide and metam sodium can severely injure any tissue they touch. Effects from even minor exposures can include burning and itching of the eyes and skin, respiratory tract irritation as well as coughing and nose bleeds. Fumigants can severely injure the lungs.

Organochlorines: Many banned pesticides (including DDT) are organochlorines, although several organochlorine pesticides are still in use in California, including lindane and parathion. Organochlorines are central nervous system stimulants that can cause tremors, hyperexcitability and seizures. Although these pesticides are generally less acutely (immediately) toxic than organophosphates or carbamates, since they persist in the environment and tend to accumulate in tissue as they pass up the food chain, they are extremely hazardous. Organochlorine pesticide residues and breakdown products are found in human breast milk worldwide, and also in soil and plant and animal tissue from the middle of the Pacific Ocean to the Arctic Circle.

Pyrethroids: These organic compounds, similar to the natural pyrethrins produced by chrysanthemum flowers, are promoted by their manufacturers as harmless to humans, and are in increasingly wide use. In fact, pyrethroids are a synthetic copy of a natural poison. While pyrethroids are among the least toxic pesticides to humans, they are an excitatory nerve poison and known carcinogen. They are also highly toxic to insects, fish and birds, even in very small doses. While natural pyrethrum breaks down in as little as twelve hours, the synthetic forms have been engineered to be more stable, and persist in the environment for weeks.

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