Low level exposure to pyrethroid insecticides found in common pesticide brands like RAID and ORTHO result in neurodevelopmental damage to laboratory animals, reinforcing evidence of harm found in epidemiological studies on human exposure to these chemicals. According to research published in PNAS Nexus, mice exposed to the pyrethroid deltamethrin displayed atypical behavior similar to humans with developmental disorders. “We are not saying these mice have autism or that they have ADHD. That’s not the goal here,” said James Burkett, PhD, study coauthor and assistant professor of neuroscience in the UToledo College of Medicine. “What we are saying is that something in their brain has been altered by this exposure and it’s resulting in the same kinds of behaviors that we see in children with autism.”
Scientists arrived at this determination by exposing a group of mouse mothers to consistent low levels of deltamethrin in their food during preconception, pregnancy, and lactation. The study notes that the amount of pesticide provided was “well below the benchmark dose for regulatory guidance.” A separate control group was given no pesticide in its food. Offspring from the female mice were then put through behavioral tests on social behavior, restrictive or repetitive behaviors, cognition and communication.
Results found that mouse pups whose mothers were exposed to deltamethrin increased their repetitive behaviors. In tests, they buried more marbles than control pups, and performed more self-grooming than the control group. Male pups exposed to deltamethrin also produced fewer vocalizations when being separated from their mothers. Pesticide exposure also impaired learning and memory; in a fear conditioning test, exposed mice were less likely to react to a fearful event they encountered before.
In addition to behavior, scientists observed physiological changes in pups whose mothers were pyrethroid-exposed. These mice exhibited significant changes in dopamine levels and transport around the body. For autistic individuals, the metabolite homovanillic acid (HVA) is considered the earliest biomarker for the condition, and exposed mice pups displayed increased levels of the substance.
“These are all similar to symptoms human patients with neurodevelopmental disorders might have,” Dr. Burkett said.
Synthetic pyrethroids are hazardous pesticides that have flown below even pesticide advocates radar for far too long, not receiving nearly as much attention as other dangerous and commonly used pesticides like glyphosate….