WASHINGTON— The Environmental Protection Agency is set to reapprove several neonicotinoid pesticides now in use across hundreds of millions of acres despite evidence from rodent studies of their potential harms to human brain development, according to a newly published scientific study.
The peer-reviewed article, published this month in the journal Frontiers in Toxicology, also documented numerous deficiencies in the EPA's regulatory oversight and analysis of the rodent studies, which were submitted to it by pesticide manufacturers. The deficiencies include the agency's failure to require the companies to provide data detailing their products' impacts at low doses, evidence that is critical to assessing potential risks.
"The data prove that neonicotinoids are terribly toxic to the mammalian brain during early life development — EPA should follow the science and restrict these harmful pesticides," said Jennifer Sass, senior scientist at NRDC (Natural Resources Defense Council) and co-author of the study.
The new study provides the first comprehensive assessment of unpublished evidence of the risks of developmental neurotoxicity, or damage to the developing nervous system, in the offspring of maternal rats who were fed the insecticides during pregnancy and lactation. The neonicotinoids tested in the five regulatory studies were acetamiprid, clothianidin, imidacloprid, thiacloprid and thiamethoxam.
The authors noted a consistent pattern: Rodents exposed to neonicotinoids in their mothers' wombs and while nursing often grew into adults with various brain regions smaller than those in unexposed rats. The study also explores similarities in the developmental effects of neonicotinoids and their chemical cousin, nicotine, a well-known developmental neurotoxin that also has brain-shrinking effects.
"Our study contributes to the growing body of evidence suggesting that neonicotinoids are hazardous to the developing human nervous system and should be avoided just as mothers abstain from smoking during pregnancy," said Bill Freese, co-author and science director at Center for Food Safety. "EPA must act to reduce the use of and human exposure to these toxic insecticides."
Because neonicotinoids are the world's most widely used group of insecticides, and are quite persistent, they are frequently found in drinking water and food and have been detected in human urine, breast milk, cerebrospinal fluid, and amniotic fluid.
Overall, the study's authors found, the EPA allowed the companies seeking approval of the neonicotinoid pesticides "to unduly influence agency decision-making." They concluded that the exposure limits set by EPA "are either not protective or not supported by available neurotoxicity data."
"These are extremely disturbing findings that expose an agency strong-armed by pesticide makers into ignoring glaring problems with critical safety assessments," said Nathan Donley, the Center for Biological Diversity's environmental health science director and a study co-author. "When the agency charged with protecting us all from harmful poisons doesn't even require the necessary data to determine significant health risks, its pesticide approvals simply can't be trusted as scientifically valid."
The study comes as the EPA is set to reapprove use of neonicotinoid pesticides for the next 15 years in a statutorily required review process now underway. Unless the agency reverses course. the deficient assessments and inadequate exposure thresholds identified by the study will be included in the approvals that are set to be finalized in 2025.
The authors of the study proposed regulatory changes to empower the EPA to provide some measure of protection to people, including: