The Environmental Protection Agency (EPA) and the State of California have once again come down on opposite sides of the ongoing Roundup debate.

This is a battle that dates back to 2017 when California’s Office of Environmental Health Hazard Assessment (OEHHA) added glyphosate — an active ingredient in Roundup —  to its list of cancer-causing chemicals under Proposition 65.

According to the OEHHA, the Safe Drinking Water and Toxic Enforcement Act of 1986, commonly referred to as Proposition 65, “requires the state to maintain and update a list of chemicals known to the state to cause cancer or reproductive toxicity.”

The EPA challenged this decision, and a federal judge temporarily barred California from enforcing the warning in 2018. However, the injunction did leave glyphosate on the state’s Proposition 65 list of cancer-causing chemicals, the Los Angeles Times reported.

The clash continued earlier this month when the EPA announced it would no longer approve product labels that claim glyphosate causes cancer, calling it “a false claim.” The news release also stated California’s Proposition 65 “has led to misleading labeling requirements for products” and that “it misinforms the public about the risks they are facing.”

The OEHHA issued a response stating that the EPA not only “mischaracterized California’s Proposition 65 right-to-know law,” it also disregards scientific research that contradicts its stance on glyphosate.

The OEHHA added glyphosate to its carcinogenic list following the World Health Organization's decision to classify the chemical as "probably carcinogenic to humans” in 2015. American legal journal The National Law Review noted that OEHHA reports from 2007 and 1997 called glyphosate non-carcinogenic.

The debate over glyphosate’s safety has recently been in the spotlight due to several high-profile court cases. According to CBS News, Bayer, which owns Roundup,  has lost three cases with damages totaling more than $190 million.

Roundup creator Monsanto, which was bought by Bayer in 2018, has also received increased scrutiny after documents at one of the trials revealed that the agrochemical and biotechnology corporation attempted to influence scientific assessments and public perception on the chemical.

There are currently about 18,000 lawsuits claiming glyphosate causes cancer. The next Roundup trial was set to begin on Aug. 19 in St. Louis, Missouri, but Reuters reported it has since been postponed until January 2020.