BELLEVUE, WASH. – Early gestational exposure to agricultural pesticides is only weakly linked to the risk of gastroschisis in offspring, suggests a case-control study conducted in California’s San Joaquin Valley, an area having among the highest levels of pesticide use nationwide.
Using data from the state and the National Birth Defects Prevention Study for the years 1997-2012, investigators led by Gary M. Shaw, Dr.P.H., assessed maternal exposure during early pregnancy to hundreds of chemicals as ascertained from state pesticide reporting data by geographic area and the women’s address of residence, obtained during interviews.
Dr. Gary M. Shaw
Analyses were based on 156 live births, fetal deaths, or pregnancy terminations affected by gastroschisis and 785 unaffected matched controls.
"Gastroschisis is a rather unique birth defect. It has a very unique epidemiology," noted Dr. Shaw, who is a professor of clinical research and a doctor of public health in the pediatrics department at Stanford (Calif.) University. "It’s one of a few or perhaps the only one that has been increasing around the world for the last 20-30 years, and it really looks like it’s a disease of young women from what we observe." Teenagers, for example, have a seven to nine times higher risk than do older women.
Overall, 35% of cases and 38% of controls had maternal pesticide exposure in early pregnancy, Dr. Shaw reported at the annual meeting of the Teratology Society. The most common chemical groups to which women had been exposed were poly-alkyl-oxy compounds, glycophosphates, organophosphorus insecticides, alcohols/ethers, and pyrethroids.
However, in adjusted analyses of 52 chemical groups restricted to those for which more than four cases or controls were exposed, only one – the triazine group – was associated with an increased risk of gastroschisis (odds ratio, 1.7), and that association was merely borderline significant, with the confidence interval including unity.