Chlorpyrifos is an organophosphate pesticide commonly used in residences until the U.S. EPA banned it from domestic use in 2001 due to its alleged, but controversial impact on neurodevelopment in children. People living in poverty, amid dilapidated and crowded conditions, are more likely to be exposed to environmental toxins, such as chlorpyrifos. But both the socially-adverse environment and the toxin may independently have impacts on neurodevelopment.

This study is designed to analyze whether neighborhood characteristics correlate with early neurodevelopment and whether these impacts confound the previously-reported link between chlorpyrifos and neurodevelopment. The study included babies born between 1998 and 2002 to African American and Dominican women living in several impoverished New York City neighborhoods. Umbilical cord or prenatal maternal plasma levels of chlorpyrifos were analyzed; prenatal neighborhood and residential living conditions and levels of poverty were identified; and, at 36 months, children’s cognitive and psychomotor development was assessed. The final sample included 266 children.

Key Findings:

• The level of neighborhood poverty was the most significant predictor of lower psychomotor and mental development scores.
• High chlorpyrifos exposure was associated with statistically significant decreases in psychomotor and cognitive development by 36 months, after controlling for other individual-level and neighborhood-level variables.
• Neighborhood poverty and characteristics did not confound or modify the previously-reported association between chlorpyrifos exposure and neurodevelopment.
• Children born before the pesticide’s ban were more likely to have high chlorpyrifos exposure levels (51 of 180 births), compared to children born after the ban (1 out of 86 births).
• High chlorpyrifos levels were only weakly associated with neighborhood poverty, but this may have been because chlorpyrifos levels were decreasing generally during the study period.
• Interestingly, housing dilapidation was not associated with decreases in neurodevelopment. This could be chance; or it reflects a particularly protective subset of mothers who zealously identified housing problems for this study and are also active in other ways to protect their children from environmental impacts.

The ban of chlorpyrifos that went into effect during the study period introduced a complicating variable. But both neighborhood poverty and chlorpyrifos exposure during the prenatal period were associated independently with lower scores of neurodevelopment at age three among New York City’s minorities. This suggests that both improving prenatal neighborhoods and toxin exposures are opportunities to promote long-term health. The introduction of neighborhood characteristics into health studies can help public health advocates deploy resources more strategically.