(Bloomberg) -- Monsanto Co. has been sued by thousands of farmers and others who blame their cancers on its massively popular Roundup weedkiller. Now Germany’s Bayer AG, which bought the agriculture giant last year, faces a claim that it deceived home gardeners about Roundup’s impact on their gut bacteria and their health.

The lawsuit, filed Wednesday in federal court in Kansas City, Missouri, claims that labels on products such as Roundup’s Weed & Grass Killer falsely assured consumers that they target an enzyme not found “in people or pets.”

According to the suit -- which names three consumers as plaintiffs seeking unspecified monetary damages and class action status -- Roundup’s active ingredient glyphosate attacks an enzyme also found in the beneficial intestinal bacteria of humans and some animals.

“Monsanto has misled consumers about glyphosate’s risks for decades,” plaintiffs’ attorney Robert F. Kennedy Jr. said in an email. “Despite the company’s efforts to suppress and skew research on glyphosate, the science is in.”

The Roundup products at issue are distributed by Scotts Miracle-Gro, which is also named as a defendant. Two other suits, in Wisconsin and Washington, D.C., are based on similar arguments but aren’t class actions.

Bayer and Scotts didn’t immediately respond to emailed requests for comment.

U.S. sales of Roundup in the gardening category totaled $295 million in 2017, according to the latest data available from market researcher Euromonitor. The chemical is also a backbone of modern farming. Monsanto’s agricultural-productivity segment brought in $3.7 billion in 2017, with Roundup sales the lion’s share.

Bayer inherited the defense of Roundup when it bought Monsanto, of St. Louis, and currently faces suits by more than 8,000 people who say the weedkiller was a factor in their cancers. Glyphosate is the most commonly used herbicide in the world, approved for weed control on more than 100 crops in the U.S. alone, according to Bayer.

In August, a jury in a California state court awarded $289 million in damages, later reduced to $78 million, to Dewayne Lee Johnson, a former school groundskeeper who claimed Roundup significantly contributed to his terminal non-Hodgkin lymphoma. The company’s share price plunged, erasing $16 billion in market value in a week.

Bayer has said that U.S. courts will ultimately find that glyphosate isn’t responsible for Johnson’s cancer. Monsanto has said for decades that glyphosate is safe.

Wednesday’s complaint focuses on glyphosate’s alleged role in the intestines. Gut bacteria have become a major focus of medical research, with an unhealthy microbiome linked to everything from obesity to depression.

“This lawsuit represents the latest front in the ongoing fight for transparency on glyphosate,” plaintiffs’ attorney Clark A. Binkley said in an email. “By filing in Missouri, we’re bringing that fight home to Monsanto.”

The case is Jones et al. v. Monsanto Co. et al., U.S. District Court, Western District of Missouri (Kansas City).

--With assistance from Jack Kaskey.

To contact the reporters on this story: Lydia Mulvany in Chicago at lmulvany2@bloomberg.net;Deena Shanker in New York at dshanker@bloomberg.net

To contact the editors responsible for this story: James Attwood at jattwood3@bloomberg.net, Peter Jeffrey, Millie Munshi

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