EPA renews approval of paraquat, including aerial application

After nine months of review, the EPA finalized its interim decision on the weedkiller paraquat on Monday, effectively keeping the herbicide on the U.S. market for 15 years. The agency decided to allow aerial application of the chemical on a broader range of crops than it proposed last October but also imposed additional steps to protect human health, such as 50- to 75-foot buffer zones around houses when applied by air.

Paraquat, first approved in 1964, is used on invasive weeds and grasses in corn, cotton, soybeans, and other crops. Usage has increased in the past decade to cope with “super weeds” that developed resistance to other herbicides.

As safety precautions, the EPA limited pilots to spraying 350 acres a day with paraquat except when it is being used to dry down cotton before harvest; required enclosed tractor cabs if a farmworker is treating more than 80 acres a day; banned the use of paraquat in backpack sprayers; and said workers cannot enter a field until 48 hours after paraquat is applied.

In October, the EPA proposed a ban on aerial applications of paraquat, except for drying down cotton. On Monday, it said aerial spraying would be allowed on all approved crops.

A 2020 study of farm families taking part in the long-term Agricultural Health Study found no association between exposure to paraquat and Parkinson’s disease, unlike a 2011 analysis. The EPA said after a thorough review of scientific literature, it “has not found a clear link between paraquat exposure from labeled uses and adverse health outcomes such as Parkinson’s disease and cancer.”

“Not only are we reapproving paraquat when the rest of the world is banning it, but we’re using more of it than ever before,” said the Center for Biological Diversity, an environmental group. The group pointed to the 2011 study on Parkinson’s and said paraquat was harmful to small mammals and birds, too.

Paraquat is highly poisonous — “one small sip can be fatal,” says EPA — and has a fearsome reputation. The form sold in the United States is dyed blue to prevent it from being confused with beverages, carries a sharp odor, and contains an agent to induce vomiting if ingested.