(461) Seasonal Associations Between Gastroschisis Rates and Pesticide Application in California

Gastroschisis is a congenital abdominal wall defect with unclear etiology. We investigated associations between seasonal rates of gastroschisis and pesticide application during the critical window of development.

Study Design:

This is a retrospective cohort study of CA linked hospital discharge-vital statistics data from 2016-2020. Gastroschisis rates were determined by zip code of maternal residence. Gastroschisis rates were organized by counties growing commodities with high pesticide application ( > 4 mill pounds applied or >3 mill acres treated). Data from the CA Department of Pesticide Regulation was used to identify the month of application of the top 100 pesticides applied. County-wide applications were categorized as “any” or “high” ( > 25%ile or >75%ile by pounds per land area, respectively). Risk of gastroschisis was analyzed by month, commodity, and amount of application by county for pesticides applied during the critical window. Statistical analysis was performed by chi squared or multivariable logistic regression.

Results:
Rates of gastroschisis births were higher in May and June (0.04%) and lower in December (0.01%) in California (p< 0.001). Analysis by commodity grown confirmed seasonal rates of gastroschisis for 9 of 13 commodities (Figure 1). Counties growing cotton had the greatest seasonal variation in gastroschisis rates (0.08% in May-June and 0.03% in December, p=0.018). We analyzed risk of gastroschisis for 14 pesticides highly applied during the critical window (Figure 2). Any application of sulphur, paraquat dichloride, and chlorpyrifos was associated with increased risk of gastroschisis. High application of pendimethalin, sulphur, paraquat dichloride, chlorpyrifos, urea dihydrogen sulfate, methoxyfenozide, and azoxystrobin was associated with increased odds of gastroschisis.

Conclusion:

There are seasonal trends of gastroschisis births in CA that are also associated with specific commodities. Pesticides highly applied during the critical window of development are associated with increased risk of gastroschisis.