The federal government on Friday proposed eliminating restrictions on corn and soybean seeds that are genetically engineered to resist a common weed killer, a move welcomed by many farmers but worrisome to scientists and environmentalists who fear it could invite growers to use more chemicals on crops.
The herbicide known as 2,4-D has had limited use in corn and soybean farming because it becomes toxic to the plants early in their growth. The new seeds would allow farmers to use the weed killer throughout the plants' lives.
Farmers have been eager for a new generation of herbicide-resistant seeds because of the prevalence of weeds that have become immune to Monsanto's Roundup. But skeptics are concerned use of the new seeds and 2,4-D will only lead to similar problems with weeds resistant to that chemical.
Scientists and environmentalists also say 2,4-D can easily drift beyond the area where it is sprayed, threatening neighboring crops and wild plants.
Most corn and soybeans grown in the U.S. are already genetically engineered, usually with a Roundup-resistant trait.
The U.S. Department of Agriculture's plant-inspection agency concluded that the greatest risk from the new seeds developed by Dow AgroSciences was increased use of 2,4-D, which could hasten the evolution of weeds resistant to it.
But, the agency said, resistance could develop anyway because 2,4-D is the third most-used weed killer in the nation.
For now, the seeds can only be used in tightly controlled trials. But the USDA's Animal and Plant Health Inspection Service published a draft environmental-impact statement Friday as part of the process for potential deregulation of the seeds.
The public has 45 days to comment on the report. The government has considered 2,4-D to be safe, but the Environmental Protection Agency is conducting a separate review on the impact of expanded use. It's expected to release a report in the coming months.
The EPA and the USDA are expected to make final decisions simultaneously on use of the chemical and seeds. That could happen in the spring or early summer.
Dow AgroSciences has asked the USDA to deregulate one variety of corn and two varieties of soybeans. Both soybean varieties resist 2,4-D, but they differ in their immunities to other herbicides. The corn resists 2,4-D and glyphosate, the generic form of Roundup.
The USDA said farmers could help curb weeds' resistance to 2,4-D by using a variety of means to fight weeds and not relying solely on it.
Among its critics, 2,4-D is best known as a component of the Vietnam War-era herbicide Agent Orange, which has not been produced since the 1970s.
Agent Orange has been tied to health problems in Vietnam veterans, but scientists do not believe 2,4-D was the culprit. Instead, their research focused on dioxin, a cancer-causing substance found in another ingredient known as 2,4,5-T, which was banned by the EPA in 1985.
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