EPA tightens limit on popular weedkiller

By Marc Heller | 07/10/2024 01:28 PM EDT

The agency ditched the Trump-era approach for atrazine with a new standard geared to better protect aquatic plants and animals.

An ear of corn.

EPA settled on a middle ground in determining what level of the weedkiller atrazine poses a danger to aquatic plants. The herbicide is used widely on corn and sorghum crops. Sean Gallup/AFP via Getty Images

The Biden administration settled on a middle ground between a much more protective limit on the weedkiller atrazine that the Obama administration had endorsed and a level the Trump administration adopted over the objections of agency career staff.

In an announcement Monday, EPA said a 2023 scientific review indicated a level of 9.7 micrograms per liter was warranted and will be used in forthcoming regulations to protect aquatic plants as well as as fish, invertebrates and amphibians.

The revised minimum level hands a victory to farmers who use it widely on corn and sorghum.


The new level is an increase from the 3.4 micrograms per liter the Obama administration settled on in 2016. But it’s less than the 15 micrograms per liter adopted during Trump’s presidency, which EPA this week said had been a policy-based decision rather than a scientific one. The Biden administration had proposed returning to the Obama-era level shortly after taking office in 2021.