It's known that pesticides reach the fetus, "because we find traces of pesticides in umbilical cord blood," Spaeth said. "Pesticides can also accumulate in breast milk, so you get a double whammy for infants who can be exposed in the womb, and then after birth."
Dr. Michael Katz, interim medical director for the March of Dimes, cautioned against drawing firm conclusions from the study. Although it was carefully designed and conducted, he said, researchers found an association between pesticide exposure and shorter pregnancies and lower birth weights, but they don't show that the pesticides caused the fetal effects.
That would require a randomized controlled trial, which is unlikely to ever be done because ethical constraints prevent scientists from deliberately exposing kids to pesticides.
In addition, the differences in birth weight and pregnancy length were minor and fall within what are normal variations, Katz added.
"The differences were very small, and there are things that can be statistically significant but aren't biologically significant," he said.
Researchers can't explain why they saw racial differences in the effect on fetuses. Prior research, however, has shown racial differences in how people metabolize toxins, while blacks and whites may be exposed to different organophosphates, experts said.
The U.S. National Institute of Environmental Health Sciences has more on pesticides.
SOURCES: Bruce Lanphear, M.D., M.P.H., clinician scientist, Child & Family Research Institute, BC Children's Hospital, and professor, health sciences, Simon Fraser University, Vancouver, B.C., Canada; Kenneth Spaeth, M.D., M.P.H., director, Occupational and Environmental Medicine Center, North Shore-LIJ Health System, New Hyde Park, N.Y.; Mic
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