Report:Effect of pesticide exposure on birth outcomes

Researchers unravel the negative effects of pesticide exposure on birth outcomes, such as weight, gestation and abnormalities.  A new study by researchers at UC Santa Barbara addresses the issue in a novel way — by analyzing birth outcomes in California’s San Joaquin Valley.With more than one-third of the country’s vegetables and two-thirds of its fruits and nuts produced there, the San Joaquin Valley, not surprisingly, is a heavy pesticide-use region. The UCSB team investigated the effect of exposure during pregnancy in this agriculturally dominated area and observed an increase in adverse outcomes accompanying very high levels of pesticide exposure.Their findings appear in the journal Nature Communications. “For the majority of births, there is no statistically identifiable impact of pesticide exposure on birth outcome,” said lead author Ashley Larsen, an assistant professor in UCSB’s Bren School of Environmental Science & Management. “Yet mothers exposed to extreme levels of pesticides, defined here as the top 5 percent of the pesticide exposure distribution, experienced between 5 and 9 percent increases in the probability of adverse outcomes with an approximately 13-gram decrease in birth weight.”They found negative effects of pesticide exposure for all birth outcomes — birth weight, low birth weight, gestational length, preterm birth, birth abnormalities — but only for mothers exposed to very high levels of pesticides — the top 5 percent of the exposure distribution in this sample. This group was exposed to 4,200 kilograms of pesticides applied in the 1-square-mile regions encompassing their addresses during pregnancy.