IARC Evaluates Carcinogenicity of Insecticides DDT and Lindane, Herbicide 2,4-D
A working group convened by the International Agency for Research on Cancer (IARC) has evaluated the carcinogenicity of the insecticides gamma-hexachlorocyclohexane (lindane) and dichlorodiphenyltrichloroethane (DDT), and 2,4-dichlorophenoxyacetic acid (2,4-D), an herbicide. Following a review of the latest available scientific literature, the IARC group classified lindane as carcinogenic to humans based on “sufficient evidence” for the insecticide’s carcinogenicity for non-Hodgkin lymphoma. The group classified DDT as probably carcinogenic to humans due to “sufficient evidence” that it causes cancer in experimental animals and “limited evidence” of its carcinogenicity in humans. According to IARC’s press release, epidemiological studies found positive associations between exposure to DDT and non-Hodgkin lymphoma, testicular cancer, and liver cancer, and “strong experimental evidence” shows that DDT can suppress the immune system and disrupt sex hormones. IARC classified the herbicide 2,4-D as possibly carcinogenic to humans based on “inadequate evidence” of its carcinogenicity in humans and “limited evidence” in experimental animals. The agency’s detailed assessments of lindane, DDT, and 2,4-D will be published as IARC Monographs, which identify and evaluate environmental factors that can increase carcinogenic risks to humans. IARC is the specialized cancer agency of the World Health Organization, and government agencies worldwide use its monographs as scientific support for their actions to prevent exposure to potential carcinogens. For more information, see the summary of IARC’s final evaluations online in The Lancet Oncology.