If you live in Champaign County, odds are you’re close to soybean fields – and to the weed killers sprayed on them.
A new analysis by Tufts University researchers found that 45% of the county’s residents lived near heavy 2,4-D use in 2023, nearly double the share in 2017. Statewide, farmers applied more than 2 million kilograms of the chemical that year – over four times the level recorded just six years earlier.
What worries experts is how much of this spray can end up beyond the fields. 2,4-D is known to drift off fields and seep into homes, where it can collect in dust and persist long after spraying. The study notes that in an 11-state review of pesticide poisoning cases, drift exposure accounted for the largest share of illnesses among farmworkers and nearby residents, with chlorophenoxy herbicides like 2,4-D linked to dozens of incidents.
Researchers have linked it to hormone disruption, cancer and developmental harm in children – risks that grow as spraying ramps up across the state.
Farmers applied 482,335 kilograms (about 1 million pounds) of 2,4-D to soybeans in 2017, compared with 2,190,914 kilograms (4.83 million pounds) in 2023 – a 341% increase, according to the study. Some counties saw jumps above 600% while the area of soybeans planted statewide has remained relatively stable over time.
Once the fourth most-used pesticide on soybeans, 2,4-D has climbed to second place in Illinois, trailing only glyphosate.
Researchers say the timing isn’t accidental: 2,4-D-resistant soybean varieties became widely available in 2019, encouraging greater use. Illinois, the nation’s top soybean producer, devotes more than 30% of its farmland to the crop.
The surge has heightened potential exposure for people living near farm fields. In Champaign County, the study’s focus, nearly 99% of residents live within 1 kilometer (about two-thirds of a mile) of at least 10 acres of soybean crops.
Researchers combined government crop maps, pesticide use reports, and census data to pinpoint where potential non-farm exposure is highest. They say the results could help health officials target testing, monitoring, and education efforts in the most affected areas.
