The health agency says the effects on humans are inconclusive
In a decision that angered many toxicologists and pesticide experts, the World Health Organization has classified 2,4-D as an agent that “possibly” causes cancer in humans.
The International Agency for Research on Cancer (IARC), a division of the WHO that identifies causes of cancer so preventive action can be taken, reviewed research on 2,4-D at an early June meeting in France.
In late June, IARC members published a summary of their findings, which concluded that 2,4-D, the world’s oldest herbicide, is “possibly” carcinogenic because:
Read Also
Chinese, Indian tariffs take toll on pea prices
The disruption of pea exports from Canada’s largest customers will likely result in slow pea exports for the remainder of the crop year.
- There was “limited evidence” that 2,4-D causes cancer in experimental animals.
- There was strong evidence that 2,4-D causes oxidative stress, an im-balance in the production of free radicals and the body’s ability to neutralize the free radicals.
- There was “inadequate evidence” that 2,4-D causes cancer in humans.
IARC completed a similar review of glyphosate in March, which concluded that glyphosate, the most popular herbicide in the world, “probably” causes cancer in humans.
DowAgrosciences, which manufactures 2,4-D, said the IARC decision is inconsistent with decades of research.
“No herbicide has been more thoroughly studied and no national regulatory body in the world considers 2,4-D a carcinogen,” said John Cuffe, global regulatory sciences and regulatory affairs at Dow AgroSciences.
Julie Goodman, an epidemiologist and toxicologist who works for the 2,4-D Task Force, which is funded by Dow and other companies that hold 2,4-D registrations, said IARC uses a hazard assessment rather than a risk assessment.
A risk assessment accounts for real world exposures.
“What’s important is that when you do a risk assessment, there is absolutely no indication that there is a cancer risk to humans,” she said.
“This has been done by over 90 health and safety regulatory agencies around the world, and none of them has concluded that 2,4-D is carcinogenic.”
The IARC classification could be significant for public perception because Dow is expecting farmers to use much more 2,4-D in coming years.
The company has developed and has registered Enlist, a new weed control system for corn and soybeans. The genetically modified technology provides “stacked” herbicide tolerance, which allows soybeans and corn to be sprayed with 2,4-D and glyphosate.
Dow has also registered Enlist Duo, a new formulation of 2,4-D and glyphosate, which is part of the Enlist weed control system.
