Toxic Pesticides

Pesticides are chemicals and other substances that kill unwanted insects, plants, fungi and animals — and they’re especially important for agriculture. Most farmers rely on pesticides to increase the production of their crops and protect them from pests and disease.

But pesticides can also harm the environment and injure people.

Agricultural laborers and others who work directly with pesticides are most susceptible to the toxic effects. The everyday consumer may also encounter these chemicals in much lower levels through pesticide residue in food and water.

According to a 2016 article on chemical pesticides and human health in the journal Frontiers in Public Health, washing and peeling foods can’t entirely remove residues. And “safe limits” established by regulatory bodies may underestimate potential health risks because of chronic exposure to multiple chemicals.

“The combination of substances with probably carcinogenic or endocrine-disrupting effects may produce unknown adverse health effects,” the authors wrote. “Therefore, the determination of ‘safe’ levels of exposure to single pesticides may underestimate the real health effects, ignoring also the chronic exposure to multiple chemical substances.”

Pesticides are regulated at the federal level by the Environmental Protection Agency. States also oversee pesticide use, usually through their state agriculture office.

Pesticide manufacturers are required to register with the EPA and file production reports. Before a pesticide is approved for use, the agency is supposed to evaluate the potential health and environmental effects of the pesticide. The EPA can also ban pesticides it’s already approved if it later discovers they are dangerous.

Every pesticide that’s registered with the EPA must have a label that provides important information on how to safely handle the product. These labels are legally binding — meaning that it’s illegal to use a pesticide in a manner that’s not consistent with the label.

The EPA also decides the maximum levels of pesticide residues that are allowable in food.

Unfortunately, the dangers of pesticides aren’t always discovered right away.

After it was developed in the 1940s, Dichloro-diphenhyl-trichloroethane, better known as DDT, was used on a widespread basis to combat the spread of insect-borne diseases such as malaria. It wasn’t until 1972 — after DDT was linked to cancer and found to threaten wildlife — that the United States banned the use of DDT.

Today, other pesticides are generating similar concerns.

As the EPA notes, paraquat is “highly toxic,” one “small sip can be fatal” and “there is no antidote.” It is also one of the most widely used herbicides in the United States.

In July 2021, after reviewing public comments, the EPA released an interim decision that established elevated prohibitions, limitations and requirements in an effort to further limit paraquat exposure. The EPA’s new “enforceable mitigation measures” include: 

• Prohibiting: pressurized handgun and backpack sprayer application methods, as well as the use of human flaggers.
• Limiting: aerial applications to a maximum of 350 acres per applicator per 24-hr period for all uses except cotton desiccation and the maximum application rate for alfalfa to one pound of paraquat cation per acre.
• Requiring: a residential area drift buffer for all aerial applications; enclosed cabs if area treated in 24-hour period is more than 80 acres; enclosed cabs or PF10 respirators if area treated in 24-hour period is 80 acres or less; a 7-day restricted entry interval (REI) for cotton desiccation; a 48-hour REI for all crops and uses except cotton desiccation; and mandatory spray drift management label language. 

Because the dangers of paraquat exposure are so extreme, all paraquat products registered for use in the U.S. are Restricted Use Pesticides (RUPs) and are not available for consumer use. Only professionals who are trained and certified can use them. However, the EPA did update its Restricted Use Pesticide statement on paraquat labels. Uncertified truck drivers can transport paraquat under certain conditions.

While the EPA has toughened rules around paraquat’s use, people have been exposed and experienced serious health complications. Because of these long-term health effects, as well as allegations that paraquat product manufacturers knew of the dangers and did not adequately warn the public, the volume of paraquat lawsuits filed led the the United States Judicial Panel on Multidistrict Litigation to consolidate them. As of July 2021, 173 federal cases were pending.

In 2018, The New York Times reported that a study conducted by the Environmental Working Group had found elevated levels of glyphosate in Cheerios, granola bars and 29 other breakfast foods made from oats. The controversial herbicide is the main ingredient in Monsanto’s Roundup weed killer, the most-used pesticide in the world.

California scientists have said Roundup can cause cancer in humans, and the World Health Organization has declared it a “probable human carcinogen” — one of five categories the EPA uses to classify chemicals based on their likelihood to cause cancer in humans.

A California jury agreed and, in 2018, awarded $289 million in damages to a former school groundskeeper who claimed he had developed cancer after regular exposure to the chemical.

The EPA has said glyphosate is “not likely carcinogenic.” But hundreds of other Roundup lawsuits are pending against Monsanto, which is a division of Bayer AG.

On August 6, 2024, the EPA used its emergency authority to ban the sale and use of Dacthal, citing its link to severe fetal health issues. Dacthal, known as Dimethyl Tetrachloroterephthalate (DCPA), is produced by AMVAC Chemical and widely used on crops like broccoli, onions, and lawns, including golf courses and sports fields. However, growing evidence suggests that Dacthal exposure poses significant risks to pregnant women and their unborn babies.

The EPA warned that exposure to Dacthal could lead to dangerous levels of pesticide in the body, potentially affecting fetal thyroid hormone levels. This disruption can result in congenital disabilities, including low birth weight, impaired brain development and motor skill issues in children.

The EPA’s decision followed years of the agency urging AMVAC Chemical to provide detailed safety studies. Despite these requests, AMVAC’s responses were delayed and incomplete, further heightening concerns. Prior studies, including one from the University of California at Berkeley, revealed that Dacthal was detected in over 50% of teenage girls from farmworker communities, emphasizing its widespread impact.

The Dacthal ban aims to prevent further exposure and protect public health. However, people already harmed by the herbicide may seek legal action, filing Dacthal lawsuits claiming that the manufacturer failed to warn about these severe dangers.

Malathion, an organophosphate, is another common pesticide under scrutiny. Farmers, residential landscapers and other workers in the United States use about 1 million pounds of the insecticide every year to control a range of pests.

Public health officials use it to get rid of mosquitoes. Others use it to combat fruit flies. It’s also a common ingredient in shampoos used to kill lice.

Accidentally inhaling or ingesting malathion can disrupt your nervous system and make you sick.

Some studies have suggested a link between malathion exposure and possible developmental disorders in children. And the World Health Organization has classified the chemical as a probable human carcinogen.

A 2017 “biological analysis” of the chemical by the EPA found that malathion is “likely to adversely affect” 97 percent of the federally protected species it comes in contact with.

In 2018, several conservation and public health groups sued the EPA, the U.S. Fish and Wildlife Service and the Department of Interior for “failing to protect endangered wildlife and the environment” from the “dangerous pesticide.”

A chemical called dicamba is also generating controversy. The 1960s-era herbicide controls weed growth in certain grain crops, grasslands and pastures. But because many plants are extremely sensitive to the toxic weed killer, the EPA for many years only permitted dicamba spraying on fields before they were planted.

That changed in 2017 when Monsanto Co. and the German chemical company BASF introduced a less volatile formulation of dicamba alongside new varieties of soybean and cotton seeds that had been genetically altered to tolerate the herbicide.

The idea was to provide an alternative to Roundup because weeds were becoming resistant to it. Many farmers jumped on board and planted 25 million acres of the new seed varieties.

But there was a problem.

Dicamba doesn’t always stay put, and when the chemical drifted into neighboring farms that weren’t using dicamba-resistant seeds, it devastated their crops.

Since 2017, farmers in 17 states have filed more than 1,400 complaints regarding 2.5 million acres of crops damaged by dicamba drift. Many filed dicamba lawsuits against Monsanto that claimed the company acted recklessly and should have warned them about the potential dangers of the herbicide.

Most household uses of chlorpyrifos were banned in 2000. But the controversial insecticide is still sprayed on food crops to combat a variety of pests, including roundworms, caterpillars, beetles and weevils. It’s also used on golf courses to eradicate fire ants.

Chlorpyrifos is sold under a number of brand names, including Lorsban, Dursban, Lock-On and Cobalt. It essentially works as a nerve agent by preventing chemical communication between nerve cells, but it can also disrupt humans’ nervous systems and studies have linked the chemical to developmental delays and autism in children.

Developing fetuses exposed to the chemical via their mothers are also at risk. Even low levels of exposure can lead to potentially permanent changes in a child’s brain structure, according to a 2012 study by researchers at Columbia University, Duke University, Emory University and New York State Psychiatric Institute.

Environmental groups have attempted for years to get the EPA to ban the pesticide. While EPA scientists at the agency have also supported a ban, farm groups have fought back, arguing that it would harm food production. The U.S. Department of Agriculture has also defended the pesticide’s use, and in 2017, then-EPA Administrator Scott Pruitt rejected an outright ban on the chemical.

Since then, the battle over chlorpyrifos has moved to the courts. In August of 2018, a federal appeals court ordered the EPA to ban the pesticide. The EPA appealed that decision and the 9th U.S. Circuit Court of Appeals agreed to rehear the case in 2019. In the meantime, the controversial chemical continues to be used.

Most pesticides can pose a risk to humans and animals. To reduce your exposure to toxic chemicals, wash produce before consuming it and remove the outer leaves of lettuce and other leafy vegetables.

Some people prefer to buy organic vegetables to minimize their exposure, but it’s still important to wash your produce. While organic farmers use fewer toxic chemicals in general, most still use certain pesticides to protect their crops.

If you are using a pesticide in or around your home, be sure to read and follow all label instructions on the product.

In the event of a pesticide emergency, call 911 and the Poison Control Centers’ national hotline phone number, 1-800-222-1222. If your pet is poisoned, get emergency advice from the ASPCA Animal Poison Control Center at 888-426-4435. A $65 consultation fee may apply. You can also call the Pet Poison Helpline at 800-213-6680 and receive help for $59.