Natural Health Journals

Pesticides and Farmers’ Mental Health

Farming tractor

Use of Pesticides Linked to Suicides, Depression Among Farmers

As people have become increasingly concerned about toxic chemicals in our food, air and water, worries have been raised about what synthetic pesticides could be doing — or are doing — to those who eat foods treated with them, to the farmers and laborers who apply the compounds to crops, and to the environment.

An article published recently in Environmental Health News and in Scientific American discussed growing numbers of studies that are showing pesticides and herbicides may not only be bad for the pests and weeds they were designed to kill, but also for humans (and lower species, including fish).

In people, the studies show that long-term exposure to low doses of pesticides or herbicides from crop applications is linked to higher rates of depression and even suicide among farmers. Evidence also seems to indicate that pesticide poisoning — exposure to a heavy dose in a short period of time — doubles the risk of depression; depressive symptoms sometimes appear soon after a high exposure.

Most pesticides and herbicides work by paralyzing the nervous systems of insects, bringing natural processes to a halt and thereby killing the insect. So, it is not far-fetched to ask whether at high levels or over long periods, pesticides could harm the nervous systems of higher species, including humans.

The above article detailed the tragic example of a 55-year-old farmer in Iowa whose family had farmed for four generations. According to the farmer’s wife, who was quoted in the article, there came a point when he went from being a calm, sensible and loving man, to having a lot of trouble sleeping and thinking; he became agitated and depressed and told his wife that he felt “paralyzed.”

Before the farmer was seen by a mental health specialist, he committed suicide. His wife is convinced that it was the chemicals applied to the seeds planted on the family’s 1,500 acres that affected his brain. She now works to spread the word among other farming families about the possible risks of pesticides to human mental health.

Farming is in itself a stressful job: the farmer usually manages his own business, does physically demanding work for long hours, takes few days off — on top of the fact that weather cannot be controlled, the health of his crops or animals may falter, and changing national and global politics affect the price and demand for his products.

But some health experts believe that the chemicals used to control pests and weeds may be making things even worse for farmers and agricultural workers, by altering neurotransmitters in their brains.

An epidemiologist and psychology professor from Colorado State University who was quoted in the article stated that for many years, the farming community didn’t pay a lot of attention to the concept of mental health — farmers are traditionally no-nonsense, emotionally strong people. But in recent years, more of them have become interested in mental health issues such as depression because greater numbers are finding themselves feeling “mentally incapacitated,” according to the CSU professor.

Previous studies with rats published in, a website of the National Institutes of Health, found that giving low doses of several pesticides to the rodents, both alone or in combination, caused cellular damage in different organs and tissues.

One of the studies found that giving rats small doses of the pesticides three times a week for five weeks produced oxidative stress in their livers and brains. Oxidative stress is a term describing when a biological system produces more reactive, disease-causing “free radicals” than it is able to neutralize, or when the system is unable to keep up and repair the damage caused by the free radical atoms or molecules. Oxidative stress is a sign that a system is under duress and may be on its way to developing illness (or has already done so).

A second study investigated the effects of two synthetic compounds in the family of pyrethroids, which are pesticides and insecticides that have been increasingly used in the United States in recent years. Pyrethroids are more toxic to insects, aquatic life and mammals, and linger in the environment much longer than the natural chemicals they were patterned after, pyrethrins, which have insecticidal properties and are found in some varieties of the chrysanthemum flower.

Researchers found that giving the pyrethroids to rats “significantly lowered” production of kynurenic acid (KYNA) in the rodents’ cerebral cortex. KYNA is a natural product of the metabolism of the amino acid L-tryptophan; previous animal studies show that KYNA has anticonvulsant properties and protects the brain’s neural cells. Abnormal levels of KYNA in the system may be involved in some brain disorders like schizophrenia, and could play a role in neurologic conditions such as tremors in Parkinson’s disease and epileptic seizures. Several studies funded by the National Institute of Environmental Health Sciences in the last several years found that farmers and others who are persistently exposed to pesticides in California’s agricultural Central Valley are more likely to have Parkinson’s disease than those who are not exposed.

In September 2014, epidemiologist Freya Kamel, PhD, of the NIEHS, and her colleagues reported the results of a study involving 19,000 American farmers and other pesticide applicators. The researchers found that farmers who used two classes of pesticides and seven individual pesticides had a greater chance of having been diagnosed with depression. Farmers using organochlorine insecticides were up to 90 percent more apt to have been diagnosed with depression, compared to those who had not used them. That study’s authors concluded that there is a “positive association” between depression and occupational exposure to those pesticides. (Source: Environmental Health Perspectives.)

Dr. Kamel’s large study found that farmers in Colorado who sustained pesticide poisoning doubled their risk of depression in the next three years. North Carolina and Iowa pesticide applicators in the study who had gotten pesticide poisoning were 2.5 times more apt to be diagnosed with depression later on.

The effects of pesticides and herbicides on the nervous systems of applicators are being seen worldwide. A study published in 2013 found that farmers in France who used synthetic herbicides were almost twice as likely to have been diagnosed with depression than those who did not use the chemicals. The risk of depression was even greater when the farmers had used the herbicides for more than 19 years.

Studies done in Brazil, where suicide rates are increasing in rural areas, found that heavy pesticide use was linked to more suicides among agricultural workers, more hospitalizations due to suicide attempts, and mood disorders, including depression, when compared to three reference populations.

In China, a World Health Organization survey of close to 10,000 people in rural Zhejiang province found that those who stored pesticides at home were more than twice as likely to have suicidal thoughts.

Farming, what should be a less stressful occupation than life in the big cities, seems to have become unduly taxing for the minds and brains of many who practice it. Occupational Safety and Health Administration data for the last 19 years show that farmers are 3.6 times more likely to die from suicide than people in other professions.

Studies show that many synthetic pesticides can also harm some species of fish, crustaceans and smaller aquatic organisms; they can also pose a danger for insect-eating birds, as the insects have the poisons in them.

In addition, pesticides are often toxic not only to the insects they’re intended to kill, but to beneficial insects such as bees. Neonicotinoids, a newer class of pesticides currently in use in the United States, are suspected of causing bee die-offs by damaging the insects’ brains and nervous systems, leading to paralysis. Sometimes, beneficial insects are harmed by lower doses of the poisons than the pests for which they’re used. It is unknown at this time what effect neonicotinoids may have in mammals, as no studies have been done so far.

In view of the sizable evidence that synthetic pesticides and herbicides are harming much more than just the pests and the weeds they were intended to kill, it is clearly time for food producers to start using only natural, non-toxic methods of controlling weeds, insects and fungal infestations.

And natural methods do exist; these include rotating crops, so that the soil won’t be continually depleted of or filled with the same nutrients, as different crops use and deposit different nutrients in the land. Keeping the soil in healthy condition helps prevent plant diseases.

Another natural strategy is to plant “cover crops,” plants seeded into agricultural fields during or outside of the growing season. Cover crops help attract beneficial insects, repel pests and weeds, nourish the soil, improve its quality and manage water content.

Natural ways to control weeds include mechanical or manual pulling of weeds, and tillage, which is turning over the soil using tractor-mounted plows.

By Cynthia Sanchez. A graduate of the University of Washington, Cynthia has extensive experience writing about health and wellness topics for different media.

Leave a Reply

Your email address will not be published.