Studies have linked long-term health issues, while regulators insist breaches of safe limits are rare
What are pesticides?
The Environmental Protection Agency (EPA) defines pesticides as any chemical substance used to regulate, prevent or destroy plants or pests – usually insects, rodents or microorganisms such as fungi and bacteria – or that acts as a nitrogen stabilizer in soil.
One billion pounds of conventional pesticides are used annually in the US, according to the latest EPA data available. The Food and Drug Administration (FDA), which monitors residues in food, found tested samples very rarely exceeded limits on pesticides and other chemicals, which the EPA says are calculated on “reasonable certainty of no harm”.
Residues are in up to 70% of produce sold in the US, according to the latest annual analysis of US Department of Agriculture (USDA) data by the health advocacy group Environmental Working Group.
Some persistent pesticides have been found to concentrate in the milk and meat of farmed animals through contaminated animal feed, various researchers around the world have found, as well as in fish in contaminated waters. A 20-year study by the US Geological Survey, for example, found pesticides at levels potentially harmful to aquatic life in 60% of the country’s rivers and streams in agricultural areas (that figure jumps to 90% in urban areas).
Up to 50 million Americans could be drinking from groundwater potentially contaminated with pesticides, according to a 2000 study by the USDA. Pesticides have also been found in pet shampoos, building materials and boat bottoms.
Can pesticides cause harm?
A growing number of studies have linked pesticides to various human health effects, though these are still hotly debated. A 2004 review co-authored by the National Cancer Institute concluded that “epidemiological evidence clearly suggests that at current exposures pesticides adversely affect human health”. Some pesticides are also known to disrupt endocrine or hormone function, research reviewed by the EPA and published in a toxicology handbook states. A 2013 report commissioned by the European Food Safety Authority reviewed 600 research studies on pesticides and found the strongest associations with certain cancers, asthma, childhood leukemia and Parkinson’s disease, but couldn’t draw any firm conclusions. A response to that report noted limitations of the data and recommended new approaches to using epidemiological data in risk assessments. Pesticides are “intrinsically toxic”, the World Health Organization says.
The EPA says its regulatory actions and improvements in science over recent years has led to “an increase in the use of safer, less toxic pesticides … [and an] overall trend of reduced risk from pesticides”.
In a landmark ruling in August last year, Monsanto was found liable for causing a school groundskeeper’s cancer through exposure to Roundup, the company’s leading pesticide. Earlier this month, in a later case, Monsanto was ordered to pay more than $2bn to a couple that got cancer after using its weedkiller. Roundup, a glyphosate-based, organophosphate weedkiller, is one of, if not the most widely-used pesticides in the world. A formal review of glyphosate by the EPA and the Agency for Toxic Substances and Disease Registry (ATSDR) released this month found some statistically significant links to certain cancers, such as non-Hodgkin’s lymphoma.
Farm workers face significantly higher exposure than the general population. Pesticides have been linked to a list of long-term health issues, including: prostate, lung, thyroid and bone marrow cancer; diabetes; Parkinson’s disease; asthma and macular degeneration, according to the Agricultural Health Study, a government-funded research study that has monitored nearly 90,000 farmers and their spouses since the early 1990s. Acute pesticide poisoning may cause, along with short-term effects, long-term neurological damage, an EPA manual for healthcare providers warns.
Organophosphate (OP) pesticides, which include glyphosate and chlorpyrifos, have been targeted by some researchers as especially harmful. University of California researchers found, in a 2018 meta-review of OP health studies, “compelling evidence” that prenatal exposure leads to increased risk of neurodevelopmental disorders and cognitive and behavioral deficits. Those researchers urged governments around the world to phase out the chemicals entirely. As of April, the EPA is under court order to decide whether to ban chlorpyrifos, which the agency found in 2017 to exceed safe standards of pesticide residue in food and water, by July.
How can consumers limit any risks?
Pesticides can enter the body through inhalation, through the skin from contaminated soil or water, or through contaminated food.
Reduce your exposure through food by peeling produce and trimming the fat from meat and fish (where pesticides might collect); washing and scrubbing fruits and vegetables under running water (not all pesticides can be washed off, the EPA says); and selecting food from different sources to avoid potentially high exposure to a single pesticide.
Buy organic where you can. But don’t avoid fresh foods if you can’t buy organic. Eat different kinds of produce to avoid potentially high exposure to a single pesticide.
Shop at your local farmer’s market and ask about pesticide practices straight from the source, or you can go even further if you have a garden and grow your own.
How are pesticides regulated?
The EPA has oversight of all pesticides used or produced in the US and sets certain safety standards for pesticides used in food in animal feed. The agency also regulates maximum limits of some pesticides in drinking water, but many remain unmonitored. While manufacturers must register all pesticides with the EPA, inert ingredients are considered “trade secrets” and do not have to be disclosed.
The US continues to use several pesticides banned in the EU or other countries, including atrazine, glyphosate, 1,3-D, paraquat and neonicotinoids. All have been linked to serious health or environmental consequences. For example, researchers at the University of California, Los Angeles found exposure to paraquat and two other pesticides increased the risk for Parkinson’s disease by three-fold, and the European Commission severely restricted neonicotinoids because of the risks to bees.
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