On July 7, the state of California will add glyphosate, the main ingredient in Roundup weed killer, to the list of chemicals known to cause cancer, but the maker of the product, Monsanto, is vowing to fight it out in court.
The agency said the designation under a state law known as Proposition 65 will proceed following an unsuccessful attempt by seeds and chemicals company Monsanto to block the listing in trial court.
Glyphosate has been a target of environmentalists and some health officials since the World Health Organization (WHO) issued a finding in 2015, saying the substance is "probably carcinogenic".
The safety of glyphosate has been debated for decades, with Monsanto long claiming that the chemical poses no risk to consumers.
Monsanto has been quick to respond to the move; as USA Today's Emily Bohatch noted, Monsanto is appealing a ruling on a case it brought against California a year ago, when the OEHHA first attempted to add glyphosate to its list of cancer-causing agents.
If added to the list, the popular weed killer would be required to add a label warning stating that it is known to cause cancer. A number of chemical companies have products containing glyphosate and they are given one year from the effective date of the listing to come into compliance with the rule, either relabeling all their products or removing them from store shelves. Introduced by Monsanto in 1974 as an effective way of killing weeds, it is used in Roundup, which is ranked as the second most widely used US lawn and garden weed killer.
Environmental groups welcomed the Office of Environmental Health Hazard Assessment's (OEHHA's) move to list the chemical.
Glyphosate has no colour or smell.
Glyphosate is sprayed on more than 200 crops across 4 million acres in California, including 1.5 million acres of almonds, making it the most widely used herbicide, according to the state Department of Pesticide Regulation, a branch of the state EPA. It's also used in landscaping, golf courses, orchards and vineyards. Almost all the corn, soy, and cotton now grown in the United States is treated with glyphosate.