“Epidemiology studies have shown that chlorpyrifos is a neurotoxin that can lead to neurodevelopmental issues, including decreased intelligence quotient (IQ) in children exposed prenatally to even low doses of the chemical.”
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Paper: https://ehjournal.biomedcentral.com/articles/10.1186/s12940-018-0421-y
Mie, A., Rudén, C. & Grandjean, P. Safety of Safety Evaluation of Pesticides: developmental neurotoxicity of chlorpyrifos and chlorpyrifos-methyl. Environ Health 17, 77 (2018). https://doi.org/10.1186/s12940-018-0421-y