State to List Monsanto's Weed Killer as a Carcinogen

Spraying glyphosate on a stubble field | Photo: Chafer Machinery, some rights reserved
Spraying glyphosate on a stubble field | Photo: Chafer Machinery, some rights reserved

California is free to officially declare that its most commonly used weed killer causes cancer, after a court ruling March 10 that shut down a lawsuit by Monsanto.

At issue: the herbicide glyphosate, sold under Monsanto’s trade name Roundup. In March 2015, the World Health Organization’s International Agency for Research on Cancer classified glyphosate as a probable carcinogen. Later that year, the California Office of Environmental Health Hazard Assessment (OEHHA) announced that it would add glyphosate to its list of chemicals known to the state to cause cancer or birth defects, a list mandated by the Safe Drinking Water and Toxic Enforcement Act of 1986, also known as Proposition 65.

Monsanto sued to block the listing in January 2016, claiming that OEHHA acted unconstitutionally in listing glyphosate. The company also argued that the value of its Roundup trademark would be irreparably damaged if glyphosate was added to the list, and that the Monsanto’s First Amendment right to free speech was in peril if the state required warning labels on glyphosate products, as is allowed by Prop 65.

Those arguments didn’t sway State Superior Court judge Kristi Culver Kapetan, who ruled March 10 that OEHHA was legally in the clear to add glyphosate to its carcinogen list.

Prop 65 mandates that businesses provide public warnings if their operations could expose members of the public to substances on the list. Those warnings often include the small labels to which Monsanto objected.

Californians long ago became quite accustomed to Prop 65  labels over the last 30 years, and it’s unlikely that such labeling would greatly affect retail sales of glyphosate. What the listing does make more likely are lawsuits by employees of companies using glyphosate on a regular basis. Prop 65 provides for large potential fines for failing to warn workers of potential carcinogens in the workplace.

Perhaps not coincidentally, workers, especially farm laborers, are the most likely sufferers of significant health effects from glyphosate exposure. Studies have linked chronic glyphosate exposure  to increased incidence of non-Hodgkin lymphoma.

The World Health Organization does maintain that the risk of illness from dietary exposure to glyphosate is very low; it’s primarily workers, rather than consumers, who face the consequences of glyphosate use.

And that use has skyrocketed in recent decades, in part due to Roundup’s reputation as safer than alternative herbicides such as atrazine, and in part because Monsanto has been selling seeds of genetically modified crops that are resistant to glyphosate. “Roundup-ready” crops such as soy, corn, alfalfa, and cotton. Farmers can, in theory, plant crops and spray Roundup on them, killing the weeds but leaving their crops unharmed.

As a result of the spread of glyphosate-resistant crops, use of the herbicide has increased more than tenfold since 1995.

Glyphosate use from 1992-2014 | Maps: USGS
Glyphosate use from 1992-2014 | Maps: USGS

As the maps above show, the bulk of glyphosate use occurs in the Midwest. In California, according to a 2015 report published by the Center for Biological Diversity, most glyphosate use is concentrated in the Central Valley, with the bulk of it in the southern San Joaquin Valley.

California glyphosate use is also concentrated in some of the state’s poorest communities. According to the Center’s report, 54 percent of California’s glyphosate spraying happens in eight of the state’s poorest counties: Tulare, Fresno, Merced, Madera, and Kern counties In the  San Joaquin Valley, along with Lake, Imperial, and Del Norte counties. The population of those eight counties is majority Latino, raising environmental justice questions about glyphosate use in the state.

“This ruling makes clear that California absolutely made the right decision to move forward in designating Roundup as a carcinogen,” said Nathan Donley, a senior scientist at the Center for Biological Diversity and a former cancer researcher. “This court acknowledged that it’s proper for the state to require common-sense labeling that accurately reflects the findings of the world’s most reliable, transparent and science-based assessment of glyphosate. Why would you want a lesser standard?”

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