Neurotoxicity - An adverse change in the structure or function of the central nervous system (CNS) and/or peripheral nervous system (PNS) following exposure to a chemical (natural or synthetic) or physical agent.

Neurotoxic - Able to produce chemically an adverse effect on the nervous system: such effects may be subdivided into two types. 1.Central nervous system effects (including transient effects on mood or performance and pre-senile dementia such as Alzheimer's disease). 2.Peripheral nervous system effects (such as the inhibitory effects of organophosphorus compounds on synaptic transmission).


Chlorpyrifos controls insects by disrupting their nerve systems. Insects are far more susceptible to chlorpyrifos than people, which is why the product can be used as an insecticide. While neurological effects can be produced with chlorpyrifos in laboratory animals based on excessive cholinesterase depression, the doses used in these cases are typically hundreds to thousands of times greater than real-world exposures from authorized product use. Used as directed, authorized chlorpyrifos applications are restricted by EPA to keep potential human exposures well below levels that could cause even nontoxic biological effects.

Further Resources

Richardson, R.J. “Assessment of the neurotoxic potential of chlorpyrifos relative to other organophosphorus compounds: a critical review of the literature” Journal of Toxicology and Environmental Health, 1995, Volume 44(2):135-165

Clegg, D.J. and van Gemert, M. “Expert Panel Report of Human Studies on Chlorpyrifos and/or Other Organophosphate Exposures.” Journal of Toxicology and Environmental Health, Part B Critical Reviews, 1999, Volume 2(3):257-79

Albers, J.W. “Absence of sensory neuropathy among workers with occupational exposure to chlorpyrifos.” Muscle and Nerve, 2004, Volume 29(5):677-686.

Eaton et al., “Review of the Toxicology of Chlorpyrifos With an Emphasis on Human Exposure and Neurodevelopment,” Critical Reviews in Toxicology, 2008, Volume 38, Supplement 2:1-125