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Thirty-five members of Congress are questioning Environmental Protection Agency Administrator Gina McCarthy about her agency's review of a controversial Dow Chemical Co. weedkiller that was the subject of a Chicago Tribune investigation last year.
In a letter sent to McCarthy late last week, Democratic lawmakers from across the country said they were concerned about the health risks posed by Dow's Enlist Duo herbicide, which combines 2,4-D and glyphosate as a one-two punch to battle weeds that have evolved to become impervious to glyphosate alone. Dow has genetically modified corn and soybeans to make them immune to Enlist Duo so that farmers can spray entire fields with the herbicide, sparing the crops but killing the weeds.
When the EPA approved Enlist Duo in 2014, the agency tossed aside evidence of kidney lesions in lab rats that Dow's own scientists said were caused by 2,4-D, clearing the way for children to be exposed to levels considered for decades to be unsafe, the Tribune investigation found.
"We were concerned to learn that, during this process, EPA dismissed a key study linking 2,4-D to kidney abnormalities based on one scientist's analysis, and in doing so, effectively gave the green light for 41 times more of the chemical to enter the America diet than was previously allowed," the lawmakers wrote.
The EPA is reconsidering its approval of Enlist Duo, but agency officials told the Tribune last December that its scientists solely are determining whether bigger no-spray zones are needed to protect endangered plants near the edges of farm fields. The fact that the agency's review is focusing only on plants and not people was troubling to the lawmakers.
"These actions do not address questions about serious potential health risks brought to light by the Chicago Tribune," the lawmakers wrote.
The congressional group is led by Reps. Earl Blumenauer and Peter DeFazio — both Democrats from Oregon — and includes Rep. Mike Quigley, a Chicago Democrat. The group asked a dozen questions about the EPA's review of the chemical and urged the agency to scrutinize everything from the human cancer risks to the environmental threat that the monarch butterfly faces when the herbicide wipes out its food source, milkweed.
"Given the widely-known adverse impacts of 2,4-D on human health and the environment, and with little understood about the implications of combining 2,4-D and glyphosate, EPA should use the utmost caution in assessing the safety of Enlist Duo before approving it for continued use," they wrote. "... The public deserves to know how EPA intends to address all of these concerns."
A Dow spokesman did not return a phone call and email seeking comment Friday. Dow has said Enlist Duo is safe and that 2,4-D is one of the most widely studied weedkillers in history.
An EPA spokeswoman declined to comment Friday. The EPA last year said 2,4-D was so safe that nobody would be harmed even if every corn and soybean farmer in America sprayed Enlist Duo.
The EPA's own worst-case estimates of exposure show that young American children could be exposed to levels of 2,4-D that the World Health Organization, Russia, Australia, South Korea, Canada, Brazil and China all consider unsafe, the Tribune found.
The World Health Organization's cancer research agency reviewed scientific studies and last year ruled that 2,4-D is possibly a carcinogen and glyphosate is a probably a carcinogen to people. In addition, 2,4-D — half of the formula for the Vietnam War-era defoliant Agent Orange — has been linked to Parkinson's disease, hypothyroidism and other health problems.
Quigley's office said the Chicago congressman decided to look into this issue after reading last year's Tribune investigation.
"It is clear that many questions still remain regarding Enlist Duo's effect on both human health and the environment, so I hope that the letter to EPA Administrator McCarthy will push her to fully and methodically reevaluate Enlist Duo's risk," Quigley said in a written statement.
A federal appeals court last month denied EPA's request to vacate its approval of Enlist Duo, a decision that keeps the weedkiller on the market while the EPA takes a second look.
Dow also is awaiting regulatory approval of its genetically modified crops in China before broadly marketing Enlist Duo to U.S. corn and soybean farmers. American grain elevators won't accept Dow's new crops until China approves them.
The market for Enlist Duo is potentially huge. Today 94 percent of soybeans and 89 percent of corn planted in the U.S. are genetically engineered to survive herbicides, primarily the glyphosate in Monsanto Co.'s Roundup. But overuse of Roundup has spawned weeds that can survive and grow 8 feet tall and as thick as baseball bats.
To battle those so-called superweeds, Dow, Monsanto and other companies are genetically modifying a new generation of crops to be immune to multiple weedkillers. Rather than replacing one weedkiller with another, they're adding more.
Blumenauer called this a "terrible cycle — and one with serious health and environmental implications."
In an email Friday, he wrote, "More attention is needed and extra care should be taken for the sake of our health and environment. That's why I'm urging EPA to re-think this, and that's why we have such strong support."
pcallahan@tribpub.com
Twitter @TribuneTrish