The International Agency for Research on Cancer (IRAC), a branch of WHO, released a statement today saying that it has evaluated the cancer causing potential of the insecticides gamma-hexachlorocyclohexane (lindane) and dichlorodiphenyltrichloroethane (DDT) and the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D).
"The herbicide 2,4-D was classified as possibly carcinogenic to humans, based on inadequate evidence in humans and limited evidence in experimental animals. There is strong evidence that 2,4-D induces oxidative stress, a mechanism that can operate in humans, and moderate evidence that 2,4-D causes immunosuppression, based on in vivo and in vitro studies," the agency said.
2,4-D has been used for more than 70-years in order to control weeds in wheat, corn, and soybean fields and even gardens and lawns, Bloomberg reports, adding that the U.S. sprayed close to 36 million pounds of the chemical in 2012.
The weed killer is a major part of Dow's chemical business, Dow AgroSciences, Bloomberg noted.
"The classification of the herbicide 2,4-D by the International Agency for Research on Cancer is inconsistent with government findings in nearly 100 countries," Dow AgroSciences said in a statement.
The company said that countries including the U.S., U.K., Japan, Germany, Canada, Brazil, and China have "for decades affirmed the safety of 2,4-D when used according to approved labeling."
Shares of Dow Chemical are up by 0.28% to $53.59 in late afternoon trading on Tuesday.