The legislation would apply to all domestic producers of herbicides and pesticides, but eliminating the failure-to-warn claims is part of Bayer’s public strategy to “manage and mitigate the risks of Roundup litigation,” according to its website.

The company hopes the U.S. Supreme Court decides that the claims are overruled by federal law, which the company predicts “could largely end the Roundup litigation.” But a federal appeals court rejected that argument in February.

Bayer says about 167,000 lawsuits have been filed by people who claim their exposure to Roundup caused ailments such as cancer, often non-Hodgkin’s lymphoma. The herbicide has been used to kill weeds for about four decades. The litigation has cost the company billions of dollars.

The U.S. Environmental Protection Agency has said Roundup’s primary ingredient, glyphosate, is not likely to cause cancer in humans and that it poses no health risks “when used in accordance with its current label.” But in 2015, the International Agency for Research on Cancer determined glyphosate is “probably carcinogenic to humans.”

That decision “opened up a floodgate — and what I’m going to call a loophole of legal practice — in which these lawsuits specifically detailed on the failure to warn,” said Sen. Jeff Edler, a Republican from State Center who managed the bill.

Edler and other Republicans argue that allegations about Roundup’s negative health effects are too flimsy to warrant the mountain of litigation that they say has driven its cost higher for crop farmers and has the potential to end its production and use.

Sen. Amy Sinclair, R-Allerton, said without Roundup, the state’s farmers “will have to return to pre-modern methods” of crop production.

Several Democrats who spoke against the bill during a Senate debate  portrayed it as a capitulation to corporations over the needs of residents and downplayed the lawsuits’ potential effects on agriculture.

“Our people in this state need to retain the ability to go to court when they have been injured, when they have fallen to disease, when their family members have died,” said Sen. Herman Quirmbach, D-Ames.

A failure-to-warn claim is a common feature of pesticide lawsuits but there are other grounds for the litigation. Lawsuits in Iowa in recent years concerning Roundup have also claimed defective design, negligence, breach of warranty, unfair and deceptive trade practices and fraud, according to court records.

The bill passed with a 30-19 vote. All Senate Democrats voted against it, and they were joined by four Republicans: Sens. Kevin Alons of Salix, Mark Lofgren of Muscatine, Sandy Salmon of Janesville, and Jeff Taylor of Sioux Center.

The bill moves to the House, where its fate is unclear. A House committee had planned to discuss a similar bill last Tuesday but didn’t.

To help avoid future lawsuits, Bayer has eliminated glyphosate from its lawn and garden herbicides, which were the source of “the vast majority of claims,” the company says. It is also developing an alternative to glyphosate.