Certain fruits and vegetables can increase the amount of pesticide chemicals found in the human body, according to a new peer-reviewed study conducted by scientists at the Environmental Working Group (EWG).
Pesticides are thought to be linked to cancer in children, reproductive problems, hormonal interference, and harm to the nervous system. Traces of these chemicals are frequently found in agricultural products, so many consumers may be exposed through their diet. The researchers say this finding could inform future research into how long-term dietary exposure to pesticides affects human health.
“The results of this study confirm that what we eat has a direct impact on the levels of pesticides in our bodies,” said Dr. Alexis Temkin, vice president of science at EWG and lead author of the study. “Eating produce is essential to a healthy diet, but it can also increase exposure to pesticides.”
Increased agricultural residues are associated with increased pesticide levels
People who reported eating large amounts of fruits and vegetables known to have high levels of pesticide residues, such as strawberries, spinach, and peppers, had significantly higher levels of pesticides in their urine than those who primarily consumed low-residue produce. The results point to diet as a major driver of pesticide exposure and lay the foundation for investigating potential long-term health effects.
“This study builds on previous research showing that certain fruits and vegetables are the primary route of pesticide exposure for millions of Americans,” Temkin said. “Young children and pregnant people are particularly vulnerable to harm from exposure.”
How did researchers measure exposure to pesticides?
This study International Journal of Hygiene and Environmental Hygiene.
To conduct their analysis, EWG researchers collected U.S. Department of Agriculture data on pesticide residues in agricultural products collected between 2013 and 2018. The researchers combined these findings with dietary survey responses and urine biomonitoring data from 1,837 participants in the 2015-2016 National Health and Nutrition Examination Survey (NHANES) conducted by the U.S. Centers for Disease Control and Prevention. These datasets represent recent years of extensive pesticide tracking. NHANES biomonitoring data is currently available only through 2018.
Using this information, scientists developed a “dietary pesticide exposure score” designed to estimate an individual’s exposure based on the types of fruits and vegetables consumed and the residue levels detected in those foods. The score takes into account how often a particular pesticide is detected, the amount detected, and the relative toxicity of each chemical.
The researchers then compared those exposure scores to 15 pesticide biomarkers measured in the participants’ urine. These biomarkers represented three major pesticide categories: organophosphates, pyrethroids, and neonicotinoids.
This analysis showed a strong association between the types of produce people ate and the levels of pesticide biomarkers detected in their urine. This means that your exposure to pesticides depends on both your dietary choices and the residue levels in those foods.
Key findings regarding diet and pesticide mixtures
In addition to confirming the association between increased agricultural residues and increased levels of pesticides in the body, the study identified several important patterns.
Diet plays a big role. People who ate more produce with high pesticide residues were more likely to have those chemicals detected in their urine than those who chose options with fewer pesticide residues.
Monitoring gaps remain. NHANES tracks only a portion of the pesticides found in food and was investigated in this study. People are exposed to a variety of pesticides, which may require more extensive monitoring.
Exposure includes mixtures. Fruits and vegetables tested by the USDA contained measurable residues of 178 pesticides. However, only 42 of these chemicals matched biomarkers measured in urine samples, suggesting that total exposure may be broader than current biomonitoring capture.
Potatoes complicated the analysis. The association between agricultural product intake and pesticide levels only became apparent after potatoes were removed from the dataset. Estimating pesticide exposure from potatoes is even more difficult because potatoes are consumed in many different forms. Additional research is needed to better understand how potato consumption affects overall pesticide exposure.
Questions regarding pesticide regulations
Much of the previous research on pesticide exposure has focused on farmworkers and residential use. This study highlights that everyday food choices can also significantly contribute to pesticide exposure in the general public.
Given the wide range of exposures observed here and in other studies, this finding raises concerns about whether current safety standards set by the Environmental Protection Agency are fully protecting public health.
Although studies have linked exposure to low levels of pesticides with potential health risks, the EPA typically places limits on individual pesticides. These standards do not account for cumulative exposure to multiple pesticide residues that are commonly found together on produce inspected by the USDA.
The researchers say their exposure scoring method could help regulators and scientists better assess real-world dietary exposures and improve protection for vulnerable populations, especially children and pregnant people.
“This study, made possible only because of robust federal data, highlights why strong public health institutions remain a top priority for policymakers,” said Varun Subramaniam, a scientific analyst at EWG.
“Pesticide residue testing and CDC biomonitoring data represent the type of important research that only the government can provide, and the scale of which cannot be matched by efforts in the private sector or academic institutions,” he said.
What consumers can do
EWG continues to encourage people to eat a diet rich in fruits and vegetables, whether conventionally or organically grown.
Studies have shown that switching from conventional produce to organic produce, which is not grown using certain synthetic pesticides, can significantly lower pesticide biomarkers in the body in just a few days.
EWG recommends that when possible, prioritize purchasing organic for the most contaminated items listed in the Shopper’s Guide to Pesticides in Produce. The guide includes a “Dirty Dozen” list of produce with the most pesticide residues and a “Clean Fifteen” list of products with the lowest pesticide residues.
