Most common US pesticide may affect brain development similarly to nicotine

Industry research reviewed by independent scientists show that exposure to the nation’s most common pesticides, neonicotinoids, may affect developing brains the same way as nicotine, including by significantly shrinking brain tissue and neuron loss.

Exposure could be linked to long-term health effects like ADHD, slower auditory reflexes, reduced motor skills, behavioral problems and delayed sexual maturation in males, the new review found.

The industry science will be used by the Environmental Protection Agency (EPA) to set new regulations, but the independent scientists say they found pesticide makers withheld information or did not include required data, and allege the EPA has drawn industry friendly conclusions from the research.

Neonicotinoid residue is common on produce, and the EPA seems poised to set limits that are especially dangerous for developing children. The health threat is “worrisome stuff”, said Nathan Donley, the paper’s co-author with the Center for Biological Diversity.

“If you’re pregnant or hoping to get pregnant, I can say with certainty that the current level of human exposure deemed safe by the EPA is not protective of your future child, and it boils my blood,” Donley said. The Natural Resources Defense Council and Food & Water Watch also co-authored the paper.

The EPA said in a statement that it had not yet reviewed the new study, but the industry research has been “independently reviewed by EPA and incorporated into the most current human health risk assessments for these neonicotinoid pesticides”.

Neonicotinoids are a controversial class of chemicals used in insecticides spread on over 150m acres of US cropland to treat for pests, in addition to being used on lawns.

The pesticides work by destroying an insect’s nerve synapse, causing uncontrollable shaking, paralysis and death – but a growing body of science has found it harms pollinators, decimates bee populations and kills other insects not targeted by the chemical.

Neonicotinoids are similar in chemical structure to nicotine, and impact the same human neurotransmitters that are responsible for nervous system development and ongoing health. Though scientists long thought that neonicotinoids only impacted insects, they break down into smaller compounds that are as potent as nicotine in their effects on the human brain, Donley said.

Recent research has found the chemicals in the bodies of over 95% of pregnant women, and in human blood and urine at alarming levels. While agricultural workers face the highest exposures, the chemicals are water soluble, easily leach into soils and streams, and are common in drinking water. Neonicotinoid residue is also regularly found on produce.

The EPA is required by law to review pesticides for safety every 15 years, and the industry research reviewed by Donley’s team is part of that process.

The low- to-mid level exposures in water and food are what concerns the paper’s authors. The pesticide industry did not submit data for these levels in many cases despite the EPA asking for it, Donley said.

Still, the EPA seems poised to set new regulations without the data and has simply claimed that mid- to low-level exposures are safe, Donley added. But the available data points to health risks and research that supports the industry claim is missing.

“The strategy by pesticide companies seems to be to ignore the EPA, and instead of receiving any consequence, the EPA just kind of shrugs its shoulders and gives it a rubber stamp,” Donley said.

In another instance, EPA management overruled one of its own scientists that raised concern about neurotoxic effects, and instead adopted a statistical analysis that claimed lower doses do not have neurotoxic effects, Donley said.

It is unclear why the EPA is not demanding more data. However, it is the latest in a long string of controversies surrounding the pesticides division largely stemming from its alleged ties to the pesticide makers, and its financial reliance on them.

“It’s clear that industry is gaming the system and we don’t have anyone calling them out on it,” Donley said.