The current study, published in the April issue of Environmental Health Perspectives, looked at 314 mother-infant pairs and is part of an ongoing project by Colombia University evaluating the effects of indoor air pollutants on minority mothers and their newborns in New York City. Study authors had reported earlier that pesticide residues were detected in virtually all low-income pregnant mothers studied, noting a strong correlation between dilapidated housing and pesticide exposures. In a previous study, the project also reported associations between levels of chlorpyrifos in umbilical cord plasma and low birth weight.
This study, which compares infants born before and after the insecticides were banned for household use, demonstrated that, on average, babies born before the ban weighed 6.6 ounces less than infants born after the ban - a difference comparable to the effects of smoking on infant birth weight.
Robin M. Whyatt of Colombia Mailman School of Public Health, principal author of the study remarked, "We were surprised to see such a significant association between exposure to the pesticides and birth weight. There is no question that this is an instance where regulation worked, the EPA imposed a ban, and there was an immediate benefit."
All retail sales and indoor use of chlorpyrifos and diazinon ended in December 2001, and December 2002 respectively. U.S. EPA has estimated prior to the ban that approximately 75% of U.S. diazinon and 50% of U.S. chlorpyrifos was used for residential pest control. The ban did not affect use of the insecticides on food crops, however. An estimated 10 million pounds of chlorpyrifos continue to be used in agricultural settings, putting farmworkers, their families and surrounding communities at the greatest risk of continued exposure. Consumers are also at risk of exposure from residues in food and water.
The Columbia study combined interviews on pesticide exposure and use, data from personal air monitors worn during pregnancy, and analysis of umbilical cord plasma and infant blood. Levels of the banned insecticides were substantially lower among infants born after January 2001, after the chlorpyrifos ban was in place, while habits of using other pesticides did not appear to change over the same period.
The study found combined exposures to diazinon and chlorpyrifos were common among the mothers in the study before the ban, with both insecticides detected simultaneously in 100% of the maternal personal air samples and in over a third of cord blood samples. The study also reported a significant correlation between the two insecticides in personal air and cord blood. Higher exposures (exposure levels in the highest 25%) to the two pesticides combined was most closely linked with lower infant birth weights. Prior to the bans, 34% of infants had exposure levels of combined chlorpyrifos and diazinon; after chlorpyrifos was banned in January 2001, only one infant had high combined exposure levels.
These study findings point to an immediate, positive health effect for infants when use of chlorpyrifos and diazinon are curtailed. They also present proof that pesticide exposures that U.S. EPA once determined to present "acceptable risks" are, in fact, linked with unacceptable damage. U.S. EPA must both strengthen its assessment of health risks of pesticide exposure during pregnancy, and act immediately to ban agricultural uses of chlorpyrifos, to protect agricultural workers, their children, and consumer health.
Prenatal Insecticide Exposures, Birth Weight and Length Among an Urban Minority Cohort, Environmental Health Perspectives, April, 2004, (online March 22, 2004) http://ehp.niehs.nih.gov/docs/2004/6641/abstract.html; Birth Weights Up After EPA Pesticide Ban, Study Finds, Washington Post, March 25, 2004.