WHO re-classifies Agent Orange herbicide as ‘carcinogenic’

The US military used 2.4-D to clear areas of forest in Vietnam. [Teo/Flickr]

The International Agency for Research on Cancer (IARC) has classified the common herbicide 2.4-Dichlorophenoxyacet acid as “possibly carcinogenic to humans”. EURACTIV France reports. 

“Since its introduction in 1945, 2.4-Dichlorophenoxyacet acid (2.4-D) has been widely used to control weeds in agriculture, forestry, and urban and residential settings,” the IARC, an agency of the World Health Organisation (WHO), stated in a press release on Tuesday 23 June.

Occupational exposures to 2.4-D can occur during manufacturing and application, and the general population can be exposed through food, water, dust, or residential application, and during spraying.”

Oxidative stress

A component of Agent Orange, the herbicide used by the US military to clear areas of forest during the Vietnam War, 2.4-D has just been placed in the IARC’s chemical Group 2B. This means it is classified as “possibly carcinogenic to humans” on the basis of “inadequate evidence in humans and limited evidence in experimental animals”. Group 2A in the IARC’s classification system contains chemicals that are “probably carcinogenic to humans”, while the chemicals in Group 1 are simply labelled “carcinogenic to humans”.

Several studies have shown that 2.4-D can cause oxidative stress or even immunosuppression. “However, epidemiological studies did not find strong or consistent increases in risk of Non-Hodgkin lymphoma or other cancers,” IARC stated.

>>Read : UN cancer agency issues warning about five pesticides

This is the second time the WHO has called into question the safety of a common pesticide this year. Following the classification of glyphosate, (used in the herbicide Roundup) as “probably carcinogenic to humans” in March, Ségolène Royal, the French Minister for Ecology, ordered the product to be removed from the shelves in France by January 2016.

Both glyphosate and 2.4-D are also suspected of being hormone disruptors.

>> Read: WHO findings on weed killer will not speed up EU safety review

François Veillerette, the spokesperson for NGO Générations Futures, said, “A herbicide that we know is carcinogenic has no place in a range of products used in public or private spaces.” The NGO called for the “market withdrawal of herbicides that contain 2.4-D, including many formulas still authorised for use by amateur gardeners”.

Persistent pesticides

Aside from 2.4-D, the IARC also reclassified two other chemicals in June 2015. The pesticide lindane was placed in Group 1 (“carcinogenic to humans”) and DDT in Group 2A (“probably carcinogenic to humans”). Although the use of these two substances is limited or banned in most countries, their effects continue to be felt in the environment today.

According to a recent study, women exposed to high levels of DDT in the uterus in the 1960s are four times more likely to develop breast cancer, even more than 50 years later.

This article was originally published by Journal de l’Environnement

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