Neonicotinoid Pesticides May Cause ADHD, Behavioral Problems, Other Long-Term Side Effects: Study

Researchers warn that rodents exposed to neonicotinoid pesticides have developed neurological issues similar to those caused by tobacco in humans, suggesting that children exposed to these chemicals may also experience similar problems. However, federal regulators have consistently ignored these findings, according to a new report.

Neonicotinoid pesticides are promoted as safer for humans than older insecticides, since they target insect nicotinic receptors, more so than mammalian ones. They have been approved by the U.S. Environmental Protection Agency (EPA) for agricultural and household use for decades, and are often sprayed on rice, cotton, soybean, fruit and vegetable crops, as well as being used as seed coatings to protect against aphids and other pests.

These commonly used chemicals are currently produced by many major agricultural manufacturers, including Bayer CropScience, Syngenta, Sumitomo Chemical, Mitsui Chemicals and others. However, recent studies have shown that neonicotinoids are accumulating in soil, water and human bodies, raising concerns about their potential impact on people.

According to findings published earlier this month in Frontiers in Toxicology, a number of studies have been presented to the EPA that show rodents exposed to neonicotinoids experience brain tissue shrinkage, similar to effects seen in children whose mothers smoked during pregnancy. Researchers warn that this suggests children exposed to these chemicals could experience similar side effects from neonicotinoid pesticides, including ADHD, reduced motor skills, behavioral problems and slower auditory reflexes.

The study was conducted by a team of researchers led by Jennifer Beth Sass of the Natural Resources Defense Council in New York, as part of an effort to provide the first assessment of multiple other studies previously submitted for evaluation to the EPA by manufacturers, which show the potential effects of five different neonicotinoids on rodents.

The neonicotinoids examined in the report were:

• Acetamiprid
• Clothianidin
• Imidacloprid
• Thiacloprid
• Thiamethoxam

In one study, researchers gave female rats three different neonicotinoid doses during pregnancy and lactation. Their offspring were then subjected to different neurological tests, including brain measurements.

The research team found statistically significant brain shrinkage in regions that correlate with ADHD in humans, which is consistent with findings in children whose mothers smoked cigarettes during pregnancy.

These findings led researchers to conclude that neonicotinoids may have a similar effect on human children as nicotine from tobacco. However, it appears that the EPA has ignored these potential safety signals.

“Shrinkage of the brain regions most consistently affected across studies—the corpus callosum and caudate-putamen—suggests a possible role in the genesis of attention-deficit hyperactivity disorder (ADHD),” Sass said. “The studies also demonstrated reduced auditory startle response and suggested adverse effects on learning and memory.”

As a result, Sass and her team recommend further research into the neurotoxicity of neonicotinoids. They also recommend that the EPA take rodent studies like the ones they looked at into consideration when approving or re-approving any pesticides.

The EPA often provides waivers on rodent studies for the approval of many pesticides, including recent reapprovals of many neonicotinoids.