The teachers worked at the Sky Valley Education Center in Monroe, Washington, and claimed they suffered brain damage from exposure to polychlorinated biphenyls, or PCBs, in the fluorescent lights.

The verdict arrived Tuesday in King County Superior Court, according to Friedman Rubin, the law firm representing the teachers.

Bayer, which owns Monsanto, said the company disagreed with the verdict and may appeal.

For more reporting from the Associated Press, see below.

“This is a big step in holding Monsanto accountable,” the teachers’ attorney, Rick Friedman, said in a statement.

“The undisputed evidence in this case does not support the conclusions that plaintiffs were exposed to unsafe levels of PCBs at the Sky Valley Education Center (SVEC) or that any exposure could have possibly caused their claimed injuries,” Bayer spokesperson Susan Skiles Luke said in a statement.

The company said the light ballasts that were the focus of the lawsuit were obsolete.

“These are historic claims that relate to products Monsanto has not produced in more than 40 years,” Luke said.

This was the first of 22 trials involving teachers, parents and students who spent time at the Sky Valley Education Center.

A 2019 Associated Press investigation found that millions of fluorescent light ballasts containing PCBs probably remain in schools and day care centers across the U.S. four decades after the chemicals were banned over concerns that they could cause cancer and other illnesses.

Many older buildings also have caulk, ceiling tiles, floor adhesives and paint made with PCBs, which sometimes have been found at levels far higher than allowed by law.

PCBs are mixtures of compounds manufactured by Monsanto Co. and widely used as coolants and lubricants in electrical equipment until they were banned in 1979.

Monsanto also has faced a deluge of litigation over its weed killer Roundup. Last year, Bayer said it would pay more than $10 billion to settle thousands of lawsuits claiming Roundup causes cancer. The company said the settlement involves about 125,000 filed and unfiled claims.