If you eat a daily serving of fruits and vegetables, critical components of a healthy diet, you’re likely ingesting a hefty dose of pesticides too, new peer-reviewed research shows.
U.S. farmers apply hundreds of millions of pounds of harmful pesticides to kill insects, pathogens and other agricultural pests every year. Consumers can be exposed to these chemicals if they drink contaminated water, live or work around treated fields or eat tainted food.
People who ate strawberries, spinach, kale and other produce with high levels of pesticide residues, even after washing them, had significantly higher amounts of pesticides in their urine than those who ate less-contaminated produce, scientists with the Environmental Working Group reported Wednesday in the International Journal of Hygiene and Environmental Health.
The EWG study builds on the nonprofit group’s annual Shopper’s Guide to Pesticides in Produce, which ranks fruits and vegetables from most to least contaminated based on pesticide residue monitoring data from the U.S. Department of Agriculture.
The EWG team took that approach one step further by linking the produce rankings to what people actually eat, to see how consumption affects pesticide levels in the body, based on biomarkers in urine.
To estimate total pesticide exposure, the team calculated a cumulative pesticide “load” based on the number of pesticides detected, their toxicity and the frequency and concentration at which they were detected on more than 40 fruits and vegetables. Then they compared the estimated exposure to pesticide biomarkers in urine.
More than one pesticide was detected on most samples, with raisins having more than 13.
“This method of ranking fruits and vegetables is actually a reasonable prediction of changes that you might see in pesticide exposure for people consuming those fruits and vegetables,” said study lead Alexis Temkin, EWG’s vice president for science.
Put simply, she added, “what we eat impacts what we’re exposed to.”
Eating fruits and vegetables with the highest pesticide exposure scores was associated with higher urinary biomarker levels for three classes of neurotoxic pesticides: organophosphates, pyrethroids and neonicotinoids. These insecticides have been linked to neurodevelopmental problems, including autism spectrum disorder, neurobehavioral problems such as aggression and depression, cancer, asthma and other respiratory ailments.
Infants, children and pregnant women are most susceptible to the effects of pesticide exposure.
The study used the most recent urine biomonitoring data with the most comprehensive pesticide tracking from the Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey, or NHANES. Although NHANES measures biomarkers for just a quarter of the 178 pesticides in the USDA’s residue monitoring program, the team managed to use that subset to demonstrate the reliability of their approach to estimate exposure.
“A really powerful component of this study is they found that asking people about what food they eat is a decent predictor of the pesticide levels that they measure in people’s bodies,” said Jennifer Kay, a research scientist who focuses on the toxic effects of environmental exposures at the nonprofit Silent Spring Institute and was not involved in the research.
That means that survey data collected in epidemiology studies, for example, can be translated into likely pesticide exposures when it’s not possible to measure biomarkers, Kay said.
And being able to use survey data to estimate pesticide exposure allows scientists to account for chemicals that metabolize too quickly to be detected, Kay said. “Chemicals can be metabolized very quickly and cause a lot of harm just in that short window.”
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Donate NowBlind Spots in Pesticide Monitoring
Interestingly, the team didn’t originally see an association between the presence of pesticides on produce people consumed and their levels in the body. That seemed unlikely, so they ran a series of tests to see if a specific fruit or vegetable could have been confounding the results.
When they removed potatoes from the mix, there was a strong association.
It’s hard to determine Americans’ pesticide risks from eating potatoes, Temkin and other researchers have discovered. That’s because there’s no U.S. biomonitoring information for chlorpropham, the main pesticide used on potatoes, which the European Union moved to ban in 2019 due to acute and chronic health risks.
“The study highlights some important blind spots in how we monitor pesticide exposures in the U.S.,” said Silent Spring’s Kay.
Fungicides were among the pesticides most commonly detected at the highest concentrations on produce, Kay said, but NHANES doesn’t measure them. And the USDA doesn’t monitor certain pesticides, including glyphosate, the most commonly used pesticide in the United States, she said.
Plus, regulators still assess risk based on “acceptable” levels of exposure to a single chemical, she said. “One of the things I liked about this study is that the group’s calculations incorporate the relative level of contamination and the relative toxicity of each pesticide on each food crop to help address that cumulative impact.”
The overarching goal of the research, Temkin said, is to fill a major gap in regulatory assessments by providing a foundation for understanding how exposure to pesticide mixtures affects health.
The only way to do a study like this is with publicly available government data sources, Temkin said. But the accessibility of those data sources, along with funding for studies linking dietary consumption to exposures in different cohorts, is uncertain after the Trump administration deleted government datasets and slashed funding for health research.
Both Kay and Temkin insist the study’s results don’t change the fact that fruits and vegetables are critical to a healthy diet.
Switching to an organic diet can reduce pesticide exposure, Temkin said, but she acknowledged that is harder for those on a tight budget. That’s where the shopper’s guide comes in, she added, to help consumers decide if they want to spend more on organic for the most heavily contaminated produce.
Buying organic produce also helps push markets and food producers to invest more in organic farming, said Kay. “That, in turn, protects farmworkers from being exposed to high levels of toxic chemicals in their jobs, and it reduces the amount of pesticides that end up in our food, drinking water and environment.”
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Liza Gross is a reporter for Inside Climate News based in Northern California. She is the author of The Science Writers’ Investigative Reporting Handbook and a contributor to The Science Writers’ Handbook, both funded by National Association of Science Writers’ Peggy Girshman Idea Grants. She has long covered science, conservation, agriculture, public and environmental health and justice with a focus on the misuse of science for private gain. Prior to joining ICN, she worked as a part-time magazine editor for the open-access journal PLOS Biology, a reporter for the Food & Environment Reporting Network and produced freelance stories for numerous national outlets, including The New York Times, The Washington Post, Discover and Mother Jones. Her work has won awards from the Association of Health Care Journalists, American Society of Journalists and Authors, Society of Professional Journalists NorCal and Association of Food Journalists.
