WASHINGTON, Sept. 4, 2015 – The California Environmental Protection Agency announced Friday a notice of intent to list glyphosate, one of the most widely-used herbicides in agriculture, and three other chemicals to a list of carcinogens under the state’s Proposition 65 law.

Under the law, substances identified as carcinogens by the International Agency for Research on Cancer (IARC) are to be added to the list. There is no separate evaluation of the evidence considered by the agency.

According to Sam Delson, a spokesman the California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA), businesses with 10 or more employees that use chemicals on this list must provide a “clear and reasonable warning” of the product’s potential dangers.

This listing would not ban the use or sale of any specified substance. The notice of intent to list triggers a 30-day comment period on whether or not the IARC did in fact declare the substances as carcinogens, but Delson said the comment period will not consider the quality or nature of evidence used by the IARC.

In March, the IARC, an arm of the World Health Organization, said glyphosate was “probably carcinogenic to humans,” a move widely unpopular with many in agriculture.

Delson said the OEHHA plans to develop a safe harbor number – also known as a no significant risk level, or NSRL – to determine levels of exposure that wouldn’t require a warning. Companies using or selling glyphosate are also free to determine their own NSRL, he said.

Monsanto Spokesperson Charla Lord told Agri-Pulse that "the IARC classification overlooked decades of thorough and robust analysis by regulatory agencies, including a multi-year assessment just completed on behalf of the regulatory authority in the European Union. Another registration review is currently underway by the U.S. EPA. No regulatory agency in the world considers glyphosate to be a carcinogen.

"Regulatory agencies have already reviewed all the key studies examined by IARC – and many more – and arrived at the overwhelming consensus that glyphosate poses no unreasonable risks to humans or the environment when used according to label instructions," she added.

"Monsanto continues to join with the agricultural industry in strongly disagreeing with IARC’s classification. Glyphosate is an effective and valuable tool for farmers and other users, including many in the State of California. During the upcoming comment period, we will provide detailed scientific information to OEHHA about the safety of glyphosate and work to ensure that any potential listing will not affect glyphosate use or sales in California," Lord said.



Nathan Donley, a staff scientist with the Center for Biological Diversity, lauded the OEHHA's move, saying it is “long past time to start reining in the out-of-control use of glyphosate” in the U.S.

“The spike in usage of glyphosate is really concerning because more use equals more exposure,” Donley said. “It’s nearly impossible for people to limit exposure to this toxin because it is just so widespread. That’s why we need much tighter controls on its use.”

Three other chemicals were also detailed in the notice of intent to list: tetrachlorvinphos, an insecticide used to kill fleas and ticks; parathion, described by the EPA as an “extremely toxic” insecticide; and malathion, an insecticide that has been used in agricultural settings, but also in urban settings such as mosquito and fruit fly eradication programs.

Comments will be accepted on the notice of intent to list until Oct. 5.

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