New research has found that atrazine, a chemical used in pesticides, causes infertility and sex changes in frogs.

A group of Midwestern communities and water districts has filed a federal lawsuit against Swiss corporation Syngenta AG and its American subsidiary, to force the company to pay for removing the chemical atrazine from public water supplies, the Iowa Independent reports.

Atrazine is a weedkiller widely used by farmers in the U.S., but was banned by the European Union in 2004.

The lawsuit, filed in a U.S. District Court, claims that Syngenta knew that atrazine would contaminate public water supplies, but left local communities with the clean-up costs.

Stephen Tillery, the lawyer for the 16 cities named in the lawsuit, told the Huffington Post that the cities have spent nearly $350 million to filter the chemical.

Syngenta’s lawyer argued that the company has worked with communities to ensure that atrazine levels are kept below Environmental Protection Agency limits.

“As a hallmark of good stewardship, my client worked voluntarily with stakeholders for years and since then also with EPA to monitor the water systems where minute detections of atrazine may occasionally occur,” said Syngenta attorney Kurtis B. Reeg in a press release. “Since 2005, no water system has had an annual average atrazine level in its drinking water greater than the EPA standard, which itself carries a 1000-fold safety factor.”

However, a Natural Resources Defense Council study found atrazine levels in two Iowa watersheds greater than three times the EPA limit of 3.0 parts per billion, the Iowa Independent reports.

Reeg called the lawsuit frivolous and argued that it would only hurt U.S. farmers.

“This suit is no surprise, as the same plaintiffs’ attorneys who have been trying a wasteful case in Madison County, Ill., have been shopping this around for years,” said Reeg.

“Just last month, plaintiffs in Illinois voluntarily dismissed numerous damage and liability claims they had made in their case. With that disarray, it appears attorneys are scrambling to another venue in which to waste scarce taxpayer resources with junk science and false allegations for personal gain at the expense of U.S. agriculture.”

Syngenta estimates that atrazine is used on half of the corn acres, two-thirds of sorghum acres and up to 90 percent of sugar cane acres in the U.S.

The lawsuit comes at a time when the safety of atrazine is being called into question.

A study from researchers at the University of California-Berkeley found that exposure to atrazine levels lower than the EPA limit caused hormonal imbalances in male frogs that chemically castrated them or changed their sex to female, according to Science Daily.

Three-fourths of the 40 test frogs were rendered infertile and 10 percent changed sex.

Syngenta disputes the results of the study, arguing that the researchers used inadequate control methods, but other studies provide increasing evidence that atrazine may play a role in disrupting endocrine systems in mammals as well as amphibians and fish.

“What people have to realize is that, just as with taking pharmaceuticals, they have to decide whether the benefits outweigh the costs,” said lead author and professor of integrative biology Tyrone Hayes, Science Daily reports.

“Not every frog or every human will be affected by atrazine, but do you want to take a chance, what with all the other things that we know atrazine does, not just to humans but to rodents and frogs and fish?”

The EPA announced in October it would study the effects of atrazine. The agency’s most recent approval for the 50-year-old chemical was in 2006.

Source: Iowa Independent, Huffington Post, Science Daily