When mothers are exposed to very high levels of pesticide use in agricultural areas during pregnancy, their babies may have an increase in adverse birth outcomes across a range of metrics, a new study suggests.
Although common opinion holds that exposure to pesticides increases adverse birth outcomes, the existing body of scientific evidence is ambiguous. Logistical and ethical barriers鈥攑esticide use data are not widely available and randomized control trials are impossible鈥攈ave gotten in the way of more accurate conclusions.
For the new study, researchers addressed the issue in a novel way鈥攂y 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 research 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.
“For the majority of births, there is no statistically identifiable impact of pesticide exposure on birth outcome,” says lead author Ashley Larsen, an assistant professor in the Bren School of Environmental 糖心视频 & Management at the University of California, Santa Barbara. “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.”
Using individual birth certificate records for more than 500,000 single births between 1997 and 2011, coupled with pesticide use data at a fine spatial and temporal scale, the scientists were able to determine if residential agricultural pesticide exposure during gestation鈥攂y trimester and by toxicity鈥攊nfluenced birth weight, gestational length, or birth abnormalities.
Common pesticide may cause lung problems in kids
They found negative effects of pesticide exposure for all birth outcomes鈥攂irth weight, low birth weight, gestational length, preterm birth, birth abnormalities鈥攂ut only for mothers exposed to very high levels of pesticides鈥攖he 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.
“If we can identify where and why these extremely high levels of use are occurring, particularly near human settlements, policymakers and health workers can work to reduce extreme exposures near agricultural communities via information campaigns or farmer outreach,” Larsen explains.
Kids exposed to pesticides have smaller lungs
Numerous chemicals are used daily in close proximity to residential areas, making it difficult to ascertain a specific responsible agent. As a result, in this study, the researchers looked at the combined results from all pesticides used in the region.
“We don’t have a good understanding of how different chemicals interact with each other in the environment,” Larsen says. “Additional work is needed to understand which chemicals or combinations of chemicals are most dangerous to human health.”
The findings appear in the journal .
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