The United States Environmental Protection Agency has said an insecticide widely used on cotton plants and citrus groves can harm bees that come into contact with those crops under certain conditions.
The agency said a preliminary risk assessment of imidacloprid, a neonicotinoid insecticide chemically similar to nicotine, found that chemical residues of more than 25 parts per billion would likely harm bees and their hives and result in the bees producing less honey.
Reuters Newsagency reports the EPA, which collaborated with California’s Department of Pesticide Regulation, said data showed imidacloprid residues in pollen and nectar above that threshold level in citrus and cotton crops.
However, residues found on corn and leafy vegetables were below at-risk levels, the agency said. Some crops needed more testing.
The federal agency is expected to finalise a broader assessment of risks the chemical may pose to pollinators by the end of the year.
Debate over neonicotinoids, also known as neonics, has intensified as concern grows over the health of pollinators crucial to the production of many foods.
The EPA proposed a rule last year to create temporary pesticide-free zones when crops are in bloom and farmers are using commercial pollinators such as bees.
As the EPA warning came, the Centre for Food Safety and a coalition of farmers and agriculture groups filed a lawsuit against the EPA, accusing it of failed oversight over millions of pounds of neonic-coated seeds sold and planted.
Pesticide critics called on the EPA on Wednesday to suspend the sale and use of imidacloprid and other neonicotinoid pesticides.
“They’re not taking into account the realistic exposures in the field, they’re not looking at the impact of these pesticides on bees or wild pollinators over time,” said Lisa Archer, food and technology program director at Friends of the Earth.
Bayer Cropscience said in a statement it was reviewing the EPA’s preliminary findings, but added they appeared to “overestimate the potential for harmful exposures in certain crops, such as citrus and cotton, while ignoring the important benefits these products provide and management practices to protect bees.”