A UC-Santa Barbara study of 500,000 birth records in the San Joaquin Valley from 1977-2011 found that high exposure to pesticides as a result of living near farm fields appeared to increase the risk for women to give birth to a baby with “abnormalities” by 9 percent, said the Independent. The risks were highest for women exposed to four times the average amount of pesticides.
“Writing in the journal Nature Communications, the researchers compared this to the 5 to 10 percent increase in adverse birth outcomes that can result from air pollution or extreme heat events,” said the British newspaper. The researchers said publicly available data on pesticide use are unavailable in most of the world although there has long been interest in the impact of environmental conditions on fetal development.
Exposure to pesticides varied widely in the San Joaquin Valley, with more than half of the births in some areas with no reported use of pesticides. The Independent quoted the researchers as saying, “Yet, for individuals in the top 5 per cent of exposure, pesticide exposure led to 5 to 9 percent increases in adverse outcomes.” For women in the top 1 percent of exposure, there was “an 11 percent increased probability of preterm birth, 20 per cent increased probability of low birth weight, and about a 30 gram (1 ounce) decrease in birth weight.”
The researchers said they were unable to identify the roles of different pesticides. Leeds University professor Alastair Hay, an environmental toxicologist, told the Independent, “The sheer size of the study, and the meticulous way it has been carried out, suggest that there is an environmental hazard for mothers resident in an area with large-scale pesticide usage and that investigation of measures to mitigate exposures to the chemicals are needed.”