Risk of limb birth defects and motherʹs home proximity to cornfields Original Research Article

Background Although previous studies have linked proximity to crops and birth defects, they lacked individual-level exposure data and none was based on using planted area instead of linear proximity to crops as the exposure metric. We studied birth defects in relation to the area of corn or soybeans within 500 m of the motherʹs residence. Methods We selected all singleton births from rural areas conceived during the 2000–2004 spring-summer months (n = 48,216). We determined whether the area with corn or soybeans around the home was associated with birth defects using multiple unconditional logistic regression. Results We found that limb birth defects (ICD-9-CM 754.5, 755) increased in relation to cornfields (Adjusted OR = 1.22; 95 % CI = 1.01, 1.47 per additional 10 ha planted with corn within 500 m). None of the birth defect types studied was associated with soybeans. Conclusions In the Midwest, a significant and expanding proportion of the population is now living in close proximity to cornfields. Our results suggest that additional studies should be conducted to identify which factor(s) associated with cornfields are behind the observed increase in limb birth defects.