Developmental toxicity - Adverse effects on the developing organism (including structural abnormality, altered growth, or functional deficiency or death) resulting from exposure through conception, gestation (including organogenesis), and postnatally up to the time of sexual maturation.

Developmental Neurotoxicity - Developmental neurotoxicity is any effect of a toxicant on the developing nervous system before or after birth that interferes with normal nervous system structure or function.


University studies of several different groups of children with presumed prenatal exposure to insecticides and other substances have reported conflicting results for chlorpyrifos on issues relating to cognition and learning. One ongoing study by Columbia University researchers of children in the inner city of New York has reported subtle effects on cognitive and psychomotor development that the authors believe are linked to prenatal exposure to chlorpyrifos. But another study by University of California at Berkeley researchers of presumed prenatal exposures in a different group of children found no chlorpyrifos-specific effects. Inherent issues with study design and exposure assessment limit the confidence that can be placed on the findings of these studies. The weight of the evidence continues to demonstrate that chlorpyrifos does not cause developmental effects.

Further Resources

Whyatt, R.M. et al., “Prenatal Insecticide Exposures and Birth Weight and Length Among an Urban Minority Cohort,” Environmental Health Perspectives, 2004, Volume 112(10):1125-1132

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

Eskenazi, B., et al., “Association of in utero organophosphate pesticide exposure and fetal growth and length of gestation in an agricultural population.” Environmental Health Perspective, 2004, Volume 112(10):1116-1124

Prueitt, R.L., et al. “Hypothesis-based weight-of-evidence evaluation of the neurodevelopmental effects of chlorpyrifos.” Critical Reviews in Toxicology, 2011, Volume 41(10):822-903

Rauh, V.A., et al. “Brain anomalies in children exposed prenatally to a common organophosphate pesticide.” Proceedings of the National Academy of Sciences, PNAS Early Edition, April 30, 2012.

Li, A.A., et al., “Evaluation of epidemiology and animal data for risk assessment: chlorpyrifos developmental neurobehavioral outcomes.” Journal of Toxicology and Environmental Health, Part B Critical Reviews, 2012, Volume 15(2):109-184.

“Limitations of the Columbia University Study”, Dow AgroSciences, (2012)

“A Closer Look at Chlorpyrifos and Brain Scans”, Dow AgroSciences, (2012)

U.S. Department of Health & Human Services. Environmental Health & Toxicology site. IUPAC glossary: