Another Popular Herbicide Ingredient ‘Possibly Causes Cancer’

The World Health Organization’s International Agency for Research on Cancer (IARC) has found another popular herbicide “possibly” causes cancer in humans.

The weed killer 2,4-dichlorophenoxyacetic acid, known as 2,4-D, is the latest herbicide to be linked to cancer just months after the IARC found that Glyphosate, the key ingredient in Monsanto’s RoundUp herbicide, “probably” causes cancer. 

The IARC reviewed the latest scientific research before deciding to classify 2,4-D as “possibly carcinogenic to humans,” a step below “probably carcinogenic”. The U.S. Environmental Protection Agency has been receiving pressure to restrict or prohibit the use of 2,4-D, while some farm group and pesticide industry groups say the chemical does not need any more restriction.

Of particular interest with the recent findings is the fact that in April the EPA approved the use of Dow AgroScience’s Enlist Duo herbicide which contains 2,4-D and glyphosate. Enlist Duo is part of a partnership between Monsanto and Dow known as the Enlist Weed Control system. 

The weed controls system is the latest effort to combat the growing problem of so-called “super weeds” that have resulted from the abundant use of glyphosate-based herbicides. In order to fight off the tougher weeds, Dow and Monsanto partnered together to produce Enlist Duo.

At the time of the EPA’s approval of Enlist Duo, the Environmental Working Group condemned the decision, stating that it endangers humans, animals, and the environment. The USDA expects use of 2,4-D to increase by 200 to 600 percent by 2020.

The new herbicide works in conjunction with Genetically Modified Corn and Soybean seeds from Dow AgroSciences that are engineered to withstand both chemicals. Last fall the United States Department of Agriculture announced that it would approve the GE seeds.

Dow did not comment on the IARC classification of 2,4-D. The IARC said it chose “possibly” rather than “probably” because there was “inadequate evidence in humans and limited evidence in experimental animals” of ties between 2,4-D and cancer. The IARC said, “epidemiological studies did not find strong or consistent increases in risk of NHL (non-Hodgkin lymphoma) or other cancers in relation to 2,4-D exposure.”

Dana Loomis, a deputy section head for IARC, told Reuters the review showed mixed results, and that a “sizable minority” judged the evidence as stronger than others did.

The announcement comes just one month after 25 organizations representing farm workers, environment, and food safety organizations sent a letter to officials with the U.S. Department of Agriculture and Environmental Protection Agency calling for an investigation into claims that scientists are facing pressure and retaliation for research that presents the controversial neonicotinoid insecticide in a negative light.

The groups say they are concerned with a report from Reuters detailing threats to scientists who speak out about the dangers of the pesticide. These threats included suspension without pay, and threats of damage to careers. The scientists filed a petition in March asking for more protection

Public Employees for Environmental Responsibility executive director Jeff Ruch told Common Dreams that the petition was “based on the experiences of 10 USDA scientists” who allegedly faced backlash for research on neonicotinoid insecticides and glyphosate, as well as other topics, including genetically modified crops.