One in three people across America have detectable levels of a toxic herbicide linked to cancers, birth defects and hormonal imbalances, a major nationwide survey has found. Human exposure to the herbicide 2,4-D has substantially risen amid expanding use among farmers despite a multitude of health and environmental concerns, according to the first nationally representative study evaluating the footprint of the chemical. Researchers from George Washington university examined the urine samples of 14,395 people (aged six and older) from all walks of life who take part in the annual National Health and Nutrition Examination Survey. They looked for biomarkers to the pesticide, and compared the exposure levels detected with the use of 2,4-D from 2001 until 2014. As the pesticide grew in popularity among farmers and gardeners, so did evidence of human exposure, rising from a low of 17% in 2001-02 to a high of almost 40% a decade later. Exposure to high levels of 2,4-D, an ingredient of Agent Orange used against civilians during the Vietnam war, has been linked to cancers including leukemia in children, birth defects and reproductive problems among other health issues. The study, published online in Environmental Health, found exposure was not uniform, with several subgroups including children aged six to 11 and women of childbearing age showing substantially higher levels of 2,4-D in their urine. Overall, the amount of 2,4-D applied in agriculture increased 67% between 2012 and 2020.