The weed killer Roundup will become the latest product in California required to carry a label alerting consumers that exposure is believed to cause cancer, state regulators announced this week.

The decision marks the latest flash point in a years-long fight between environmentalists, some scientists and Roundup’s maker, the chemical giant Monsanto, with government agencies often caught in between.

It’s generating public discussion not only because of Roundup’s popularity but also because various detractors are touting the labeling as a possibly momentum-building victory against the St. Louis-based company, which they have accused of everything from hiding evidence about toxins to promoting the controversial use of genetically modified seeds.

Monsanto, which has repeatedly denied any wrongdoing, declined to comment Tuesday.


For Californians, evaluating the cautionary stickers and signs mandated by Proposition 65 is practically part of daily life. The labeling is found on everything from dietary supplements to crystal vases to gasoline pumps.

What impact — if any — does this public-alert system have on consumers and businesses? The answers range from laudatory to disparaging, depending on which experts are asked.

In 1986, California voters passed Proposition 65, also called the Safe Drinking Water and Toxic Enforcement Act. The law requires that products carry warning labels if they contain chemicals deemed by the state to pose certain health risks.

Today, it covers more than 900 substances believed to cause cancer, birth defects or reproductive harm. Warnings can be placed directly on products or posted in businesses, workplaces and rental units. There are several ways a chemical gets put on the Proposition 65 list, most notably by designated, state-qualified scientists.


California’s unique law is enforced by the state Attorney General’s Office, as well as district and city attorneys in metropolitan areas. Also, private citizens and consumer advocacy groups can file lawsuits related to Proposition 65 and are entitled to legal fees if they prevail.

Fines for violating the law can run as high as $2,500 per day.

Advocates of the labels said they have been effective, as evidenced by companies that try to avoid the cancer-causing designation for their products by changing their ingredients or fighting inclusion in the program.

“I think Prop. 65 has been a boon to consumers,” said Michael Hansen, senior scientist with the nonprofit group Consumers Union. “The list has led to a lot of reformulation of products by companies that don’t want to put a label on things or make a different product just for California.”


Opponents of the law said the now-ubiquitous warnings can lead the public to both overreact and underestimate the cancer risks posed by certain products. These signs can be confusing, they argue, especially when federal standards contradict California’s in some cases.

There’s no evidence to suggest Proposition 65 has correlated with lower cancer rates in California as compared to states without such a law, according to an often-cited paper by Michael Marlow, an economics professor at California Polytechnic State University in San Luis Obispo.

“In sum, public health has not demonstrably improved because of Proposition 65, as evidenced by this study’s empirical examination. But the law has imposed many costs on business owners, workers, customers and taxpayers,” he wrote in the 2014 assessment. Marlow was on vacation Monday and couldn’t comment for this story.

Glyphosate, the main ingredient in Roundup, has been the subject of a nearly two-year legal battle between Monsanto and the California Environmental Protection Agency. The company is appealing a Superior Court decision from March that allowed state regulators to move forward with putting the warning labels on the herbicide.


In Washington, D.C., the U.S. Environmental Protection Agency, under then-President Barack Obama, had declined to label it as a carcinogen.

Roundup is the most widely used herbicide and dessicant in California, applied to more than 200 crops stretching across millions of acres, according to the Department of Pesticide Regulation. A number of school districts in Southern California have forbidden its use, and environment groups have routinely called the product dangerous, especially for farm workers.

Critics of Roundup hailed the Monday decision as a major win for consumers. They point to a contentious 2015 ruling by the World Health Organization that said glyphosate is “probably carcinogenic.”

“Roundup is a highly popular product. People use it to kill weeds in their backyard,” said Jason Pfeifle, a public health advocate for the California Public Interest Research Group. “This sort of warning label can make them think twice before using this type of product.


“At the end of the day, we believe that consumers should have the right to know about this information regardless of what they decide to do with the information,” he added.

The varying stances between leading government agencies reflects a wide range of standards for what constitutes a potentially hazardous exposure to glyphosate as well as many other chemicals.

It’s not clear whether crops that have been sprayed with glyphosate will also require labeling.

While Gov. Jerry Brown has said the law helps inform the public and discourages stores from stocking products that contain chemicals dangerous to human health, he has also recognized the concerns of businesses.


Industry groups have routinely complained about Proposition 65 because it has allowed private attorneys to bring costly nuisance lawsuits against companies and force settlement agreements. Several years ago, for instance, there was a series of lawsuits targeting banks for not posting signs warning of health hazards — including cancer — related to second-hand smoke wafting from outdoor ATMs.

The governor’s office has labeled such efforts “shake-down lawsuits.” In response, the state now allows business 14 days to make changes in response to Proposition 65 notices issued by private parties before being hauled into court.

Industry groups have also expressed concern about new rules for warning labels that are set to go into effect in August 2018, such as a requirement that labels indicate the types of chemicals contained in a product and the route of exposure.


Twitter: @jemersmith

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Email: joshua.smith@sduniontribune.com