Lower birth weight as a critical effect of chlorpyrifos: a comparison of human and animal data

Qiyu Zhao, Bernard Gadagbui, Michael Dourson
Regulatory Toxicology and Pharmacology: RTP 2005, 42 (1): 55-63
Chlorpyrifos is an irreversible inhibitor of cholinesterase (ChE), and inhibition of ChE is believed to be the most sensitive effect in all animal species evaluated and in humans. Recent epidemiology studies reported associations between umbilical cord plasma chlorpyrifos levels and fetal birth weight decreases among minority women living in New York City during pregnancy. These associations raise questions whether impaired fetal development is the critical effect rather than the inhibition of ChE as is currently believed so. We analyze the available information from epidemiology studies and animal studies in order to identify the relative sensitivity of decreased birth weight and inhibition of ChE from exposure to chlorpyrifos. We find that the positive associations from some epidemiology studies are different from other epidemiology investigations. Moreover, a direct comparison of experimental animal neonatal information shows that cholinesterase inhibition is a more sensitive indicator of adverse effect than reduced body weight, and that neonates are equally, or perhaps less sensitive to cholinesterase inhibition than their maternal parent. Based on a review of human studies and comparison of human cord blood chlorpyrifos concentrations with blood chlorpyrifos concentrations that in animals caused effects with good dose-response, it appears unlikely that the exposure level encountered by the population reported in [Whyatt, R.M., Rauh, V., Barr, D.B., Camann, D.E., Andrews, H.F., Garfinkel, R., Hoepner, L.A., Diaz, D., Dietrich, J., Reyes, A., Tang, D., Kinney, P.L., Perera, F.P., 2004. Prenatal insecticide exposures and birth weight and length among an urban minority cohort. Environ. Health Perspect. 112, 1125-1132.] study would cause any fetal developmental effect. Moreover, the critical effect for chlorpyrifos still appears to be cholinesterase inhibition.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"