California’s Listing Widely Used Herbicide as Carcinogen Fuels Public Health Debate

California is on the verge of listing a widely used herbicide as carcinogenic for animals and probably for humans. It could be the first significant policy salvo in the United States in what is already a long, far-reaching public health debate over genetically modified crops and the chemicals used to grow them.

The chemical glyphosate, a main ingredient in the popular herbicide Roundup, was labeled as a carcinogen earlier this year by the International Agency for Research on Cancer, the World Health Organization’s cancer authority.

California’s Office of Environmental Health Hazard Assessment, acting under a state law established almost 30 years ago, announced last month that it intended to add glyphosate to the state’s list of known carcinogens, a move that will trigger further action — either adding caution labels to products containing the chemical or establishing minimum levels for human health.

Glyphosate is the most widely used herbicide in the world, largely because of widespread planting of Monsanto’s “Roundup ready'” crops genetically engineered to survive applications of glyphosate. The chemical is used on corn, soybeans, almonds, cotton, alfalfa, vineyards and other crops.

Monsanto officials, who have long argued that glyphosate does not pose a threat to humans, argued against the state’s plan to list the chemical as a carcinogen. Monsanto submitted 15 pages of comments to the OEHAA, pointing out that the state agency itself concluded in 2007 that glyphosate was “unlikely to pose a cancer hazard to humans.”

“We find it deeply concerning that OEHHA would disregard its own scientifically sound assessment and instead rely upon the flawed conclusions of a non-transparent international body,” Monsanto spokesperson Charla Lord wrote in an email.

Wide Support for State Action

A group of 18 public health, environmental, food safety and farming organizations last week submitted a letter in support of the state’s plan to add glyphosate to the list of carcinogens.

“The U.S. Environmental Protection Agency has known for years that glyphosate probably causes cancer, yet the agency has allowed Monsanto and other companies to sell more and more of it every year, without further regulation or labeling,” said Rebecca Spector, west coast director at Center for Food Safety, primary organization behind the letter supporting the move. 

“In the absence of federal action, it is imperative that California be a leader in this issue by requiring labeling of products containing glyphosate,” Spector said.    

“The EPA is a little bit behind the times on this one,” said Nathaniel Kane, attorney for the Environmental Law Foundation in Oakland.

Proposition 65 mandates that California do what the EPA has not done. Under the states’ Prop. 65 guidelines approved by voters in 1986, state officials must alert the public when a chemical is determined to be carcinogenic.

No other state has anything similar to Prop. 65, but when California formally recognizes the main ingredient in a widely known product such as Roundup as carcinogenic, other states — and perhaps the EPA — will respond.

“We’re the biggest state and decisions here reverberate around the country,” Kane said. “Having the state of California declare that a chemical is carcinogenic will focus new attention on public health

Michael Hansen, senior scientist with Consumers Union, said there is little doubt the chemical causes cancer in animals and growing suspicion that it may do the same in humans.

“The international committee was unanimous in saying glyphosate is carcinogenic for animals — all 17 committee members agreed,” Hansen said.

Hansen said there are two possible results of California’s adding the chemical to the list of known carcinogens. “It will lead either to requiring warning labels on products containing the chemical or it will lead to determining what levels are safe for humans — a process known as establishing ‘safe harbor,'” Hansen said.

Monsanto’s Arguments

In comments to the state OEHAA, Monsanto officials said listing glyphosate as a cancer cause “has the potential to deny farmers and public agencies the use of this highly effective herbicide.”

“The listing of glyphosate under Prop. 65 could have real consequences for farmers, municipalities and public agencies in California,” Lord said.

“If Prop 65 listing resulted in de-selection of the product, farmers and public agencies could be forced to resort to mechanical methods of weed control with significantly increased costs, safety concerns and risks to the environment,” Lord said.

Monsanto’s comments suggested California’s plan may be illegal, and the company claimed the state did not seek sufficient valid scientific studies before moving forward with the decision.

Monsanto has reportedly hired a third-party consulting firm for a second opinion that the company contends will show glyphosate is safe.

The WHO’s cancer committee said it examined several scientific studies in its decision, including research in Sweden, Canada and the United States

Policy Changes Possible

Health and environmental advocates hope California’s action will ultimately lead to changes in regulations governing the use of herbicides.

“I hope we see some changes,” said Bill Freese, science policy analyst for the Center for Food Safety.

“It’s already started in other parts of the world. Europe and other parts of the world are ahead of us on this,” Freese said.

France banned the sale of glyphosate in June, following similar actions in the Netherlands and Sri Lanka. Other countries including Brazil, Germany and Sweden are considering new regulations.

In the letter to state officials supporting California’s plan to list the chemical as carcinogenic, scientists from the Center for Food Safety point out the rapid rise in the use of the chemical:

“There is no doubt that both the use of and exposure to glyphosate has increased tremendously over the past two decades. In the U.S., agricultural use of glyphosate exceeded 280 million lbs. in 2012, exceeding by more than four times the amount of the second most heavily used conventional pesticide, atrazine. This represents a 10-fold increase in use since 1995, driven primarily by the widespread planting of glyphosate-resistant corn, soybeans and cotton, which each represent roughly 90% of respective crop acres.”

Because the chemical is associated with — and used liberally on — genetically modified crops, the agricultural decision to grow modified crops is expected to be part of the public health debate in California as well as the rest of the country.

“You can find glyphosate in rainfall, surface water, even in human urine,” Freese said. “How much of this is in our food is going to be a big question going forward,” Freese said.

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