The widely used herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is
“possibly carcinogenic to humans,” concludes the World Health
Organization’s International Agency for Research on Cancer (IARC).
IARC released its determination this week, based on “strong evidence
that 2,4-D induces oxidative stress,” a condition that can lead to
chronic inflammation and ultimately cancer. IARC says there is
“inadequate evidence” to fully deem 2,4-D a human carcinogen and
“limited evidence” of carcinogenicity in laboratory animals.
Chemical manufacturers are strongly disputing the “possibly”
classification, saying it is inconsistent with government findings in
nearly 100 countries, including the U.S.
“No herbicide has been more thoroughly studied and no national
regulatory body in the world considers 2,4-D a carcinogen,” says John
Cuffe, global regulatory sciences and regulatory affairs leader at Dow AgroSciences.
The company won approval late last year to market its Enlist Duo
herbicide—a mixture of 2,4-D and glyphosate—in the U.S. Many
environmental groups are concerned this will cause use of 2,4-D to
skyrocket.
Even before IARC’s evaluation, the Natural Resources Defense Council
and other environmental organizations filed lawsuits against the
Environmental Protection Agency for approving Enlist Duo. They claim the
agency did not adequately study the mixture’s effects on human health
and endangered species.