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Member Research and Reports

Maryland Researchers Investigate Prevalence of Potentially Toxic Insecticides

Neonicotinoids are the most widely used class of agricultural insecticide in the world, but researchers are increasingly concerned that their residues are contaminating the food supply, potentially leading to harmful developmental and neurological effects for humans.

A recent study led by assistant professor Dr. Devon Payne-Sturges of the University of Maryland School of Public Health, examines how prevalent these insecticides are among foods sold and consumed in the United States.

The study comes from the Maryland Institute for Applied Environmental Health (MIAEH), whose work explores the impacts of our natural and man-made environments — including air, water and food, plus our sociocultural, economic, work and family environments — on human health.

The researchers — Dr. Hillary Craddock,  Ms. Dina Huang, Dr. Paul Turner,  Dr. Lesliam Quiros-Alcala and senior author, Dr. Devon Payne-Sturges– used data collected by the U.S. Department of Agriculture between 1999 and 2015 to examine the prevalence of seven neonicotinoids among food supplies, including fruit, vegetable, meat, dairy, water, grain, honey, and baby food.

The study found that, on average, 4.5 percent of the domestic and imported commodities had detectable levels of neonicotinoids. They were most frequently identified on fruits and vegetables, including apples, cauliflower and celery, largely because the insecticides are commonly used to treat fruit and vegetable crops. But their presence on a few “off-target” items, like water and a sample of dairy, shows that they’re infiltrating the broader ecosystem, too.

[Photo: Dr. Devon Payne-Sturges]

The study notes that many of the contaminated foods are frequently consumed by young children, and some of those insecticides made their way into samples of peach-, pear- and apple-based baby food, too. Those results highlight the need to evaluate the potential health risks of ingesting neonicotinoids, especially among children and pregnant women.

Most commodities’ residue levels were far below the Environmental Protection Agency’s legal standards, but the maximum residue levels found among samples of some commodities — including tomatoes, green beans and strawberries — approached or even exceeded those thresholds.

The findings raise concerns about the cumulative risks of neonicotinoid exposure, which have never been assessed by the EPA to determine tolerance levels. Documenting the prevalence of residues in food is an important step towards understanding potential risks, the study notes.

“Our results help to identify specific foods that are sources of exposure and will inform evaluation of regulatory policies regarding agricultural practices of neonicotinoid insecticide applications,” said Payne-Sturges, an assistant professor with MIAEH and senior author on the article.

Little research exists on the extent of neonicotinoid residue in U.S. food, and the researchers say this is the first study focused on the spread of seven neonicotinoids covering the entire period since the USDA first started testing for their presence in food.

The study, “Trends in neonicotinoid pesticide residues in food and water in the United States, 1999-2015,” was published in Environmental Health.