One in three Americans exposed to toxic weedkiller: study

One in three Americans may have detectable levels of the cancer-linked herbicide 2,4-D — with young children incurring the most risk from exposure to these toxins, a new study from George Washington University has found. 

Among more than 14,000 participants surveyed, nearly 33 percent had detectable levels of the toxin in their blood, according to study, published on Wednesday in Environmental Health.

Human exposure to 2,4-D — which has been linked to cancer, reproductive issues and other health problems — has risen alongside increased agricultural use of the substance, the authors stated. 

“Our study suggests human exposures to 2,4-D have gone up significantly and they are predicted to rise even more in the future,”  Marlaina Freisthler, the study’s lead author and a George Washington University PhD student, said in a statement.

“These findings raise concerns with regard to whether this heavily used weed-killer might cause health problems, especially for young children who are very sensitive to chemical exposures,” Freisthler added. 

To conduct their assessment, the George Washington researchers looked for biomarkers of the pesticide in urine samples taken from the Centers for Disease Control and Prevention’s National Health and Nutrition Survey.

Of the 14,395 participants — from survey cycles between 2001 and 2014 — the scientists found that nearly 33 percent had detectable levels of 2,4-D in their urine. And while only 17 percent had detectable urine levels of the herbicide in 2001-2002, this figure surged to 40 percent a decade later, according to the study.

The scientists also determined that children ages 6-11 incurred 2.1 times the risk of having high 2,4-D urinary concentrations compared to participants aged 20-59 years, while women of childbearing age had 1.85 times higher odds than their male contemporaries.

While scientists have yet to determine what the impact of lower exposure to this herbicide might be, they have determined that 2,4-D is an endocrine disruptor, the researchers noted.

2,4-D was first developed in the 1940s and quickly became a popular weedkiller for farmers intent on increasing their crop yields, according to the study.

Use of 2,4-D began to decline in the 1960s, when herbicides like Roundup emerged. But by the mid-2000s, three types of “hard-to-control weeds had developed resistance to glyphosate” — the active ingredient in Roundup — leading to the reemergence of 2,4-D in weed control programs, the study said.

Some common brand names for 2,4-D, which is generally applied to foliage, include Hi-Dep, Weedar 64, Weed RHAP, Amine 4, and AquaKleen (Amines), according to the U.S. Department of Agriculture.

Children can be exposed to 2,4-D if they play barefoot on grass recently treated with the toxin, or if they put their hands in their mouths after playing in grass or soil contaminated with the chemical, the authors stated. People can also be exposed to the weedkiller by consuming soybean-based foods and through inhalation, according to the study.

“Further study must determine how rising exposure to 2,4-D affects human health–especially when exposure occurs early in life,” Melissa Perry, a professor of environmental and occupational health and senior author of the paper, said in a statement.

“In addition to exposure to this pesticide, children and other vulnerable groups are also increasingly exposed to other pesticides and these chemicals may act synergistically to produce health problems,” Perry added.