By Johnathan Hettinger and Carey Gillam
Pregnant women in a key US farm state are showing increasing amounts of a toxic weed killer in their urine, a rise that comes alongside climbing use of the chemicals in agriculture, according to a new study published Friday.
The study, led by the Indiana University School of Medicine, showed that 70% of pregnant women tested in Indiana between 2020 and 2022 had an herbicide called dicamba in their urine, up from 28% from a similar analysis for the period 2010-2012 that included women in Indiana, Illinois and Ohio.
Notably, the new study found that along with a larger percentage of women showing the presence of dicamba in their bodies, the concentrations of the weed killing chemical increased more than four-fold.
The study also looked for the presence of 2,4-dichloroacetic acid, better known as 2,4-D, in the urine samples, finding that 100% of the women in both the earlier study and the new one had 2,4-D in their urine, with detectable, but not significant, increases in concentration levels.
The new findings add to a growing body of literature documenting human exposure to chemicals used in agriculture, and various known and potential health impacts. Many scientists have particular concerns about how farm chemicals impact pregnant women and their children, but say more research – and more regulatory scrutiny – is needed.
“These are two chemicals we’re concerned about because of their increasing use,” said Paul Winchester, a neonatal physician in Indianapolis, Indiana, who was not involved in this study but has authored related studies.
Dicamba exposure has been linked to increased risk of liver and bile duct cancer. Some animal studies of 2,4-D exposure during pregnancy found low body weights and changes in behavior in the offspring, while other studies have found that exposure to 2,4-D appears to increase the risk of lymphoma.