2,4-D not carcinogenic: Health Canada

The Pest Management Regulatory Agency and Health Canada conclude it poses no health or environmental risk

Health Canada has concluded that 2,4-D is safe for humans and the environment.

In late March, the Pest Management Regulatory Agency released the findings of its special review of 2,4-D, one of the world’s oldest common herbicide.

The PMRA’s review, which be-gan in 2013, was prompted in part by Norway’s prohibition of all uses of 2,4-D.

Health Canada experts, after studying the published literature and industry safety data, decided the herbicide is not a carcinogen.

“The PMRA review of the available toxicological database for 2,4-D determined that based on in vitro and in vivo studies, all forms of 2,4-D are not mutagenic or genotoxic,” the PMRA said in a report released March 31.

“The overall weight of evidence indicates that 2,4-D is not carcinogenic in rats, mice, and dogs.”

PMRA scientists also considered the herbicide’s potential impact on the environment, particularly aquatic habitats. The PRMA came to its conclusions even when assuming high concentrations of 2,4-D.

“The risk to aquatic plants from 2,4-D in runoff is not of concern,” the report said. “Evaluation of available scientific information related to the aspects of concern for human health and the environment indicated that the registered products containing 2,4-D are acceptable for continued registration.”

The PMRA finding differs from the World Health Organization’s International Agency for Research on Cancer (IARC)

An IARC panel classified 2,4-D as possibly carcinogenic to humans last June, based on studies showing the herbicide causes oxidative stress and immuno-suppression.

However, IARC said 2,4-D was possibly carcinogenic, rather than probably, because the scientific evidence was weak.

“Epidemiological studies did not find strong or consistent increases in risk of NHL (non-Hodgkins lymphoma) or other cancers in relation to 2,4-D exposure.”

Health Canada scientists agreed with that portion of the IARC assessment.

“The available epidemiological studies provide … no evidence for an association between exposure to 2,4-D and other human cancers, including prostate, breast, pancreatic, colorectal, and brain cancers.”

Canadians can comment on the PMRA review before the agency makes its final decision.

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