May 13 (Reuters) - A California jury on Monday awarded more than $2 billion to a couple who claimed Bayer AG’s glyphosate-based Roundup weed killer caused their cancer, in the largest U.S. jury verdict to date against the company in litigation over the chemical.

It was the third consecutive U.S. jury verdict against the company in litigation over the chemical, which Bayer acquired as part of its $63 billion purchase of Monsanto last year. Both other jury verdicts also came in California, one in state court and one in federal court.

The jury in San Francisco Superior Court in Oakland on Monday said the company was liable for plaintiffs Alva and Alberta Pilliod’s contracting non-Hodgkin’s lymphoma, a spokeswoman for the couple said.

It awarded $18 million in compensatory and $1 billion in punitive damages to Alva Pilliod, and $37 million in compensatory and $1 billion in punitive damages to his wife, Alberta Pilliod. The jury found Roundup had been defectively designed, that the company failed to warn of the herbicide’s cancer risk and that the company acted negligently.

The German chemicals giant faces more than 13,400 U.S. lawsuits over the herbicide’s alleged cancer risk.

Bayer in a statement said it was disappointed with the verdict and will appeal, adding that both Alva and Alberta Pilliod had long histories of illnesses known to be substantial risk factors for non-Hodgkin’s lymphoma.

“The contrast between today’s verdict and (U.S. Environmental Protection Agency’s) conclusion that there are ‘no risks to public health from the current registered uses of glyphosate’ could not be more stark,” Bayer said.

Bayer says that decades of studies by the company and independent scientists have shown glyphosate and Roundup to be safe for human use. Bayer also points to several regulators around the world that found that glyphosate was not carcinogenic to humans.

The prior two jury verdicts against Bayer in U.S. Roundup trials triggered steep declines in Bayer shares.

Shareholders have rebuked the company’s top management over its handling of the Monsanto acquisition and the litigation it inherited, which has wiped around 30 billion euros ($33.55 billion) from Bayer’s market value since the first jury verdict. (Reporting by Tina Bellon in New York Editing by Leslie Adler)