The city of Seattle is suing to make Monsanto pay for cleanup of toxic PCBs from the city’s drainage system and the Duwamish River.

Monsanto was the sole producer of PCBs (polychlorinated biphenyls) for commercial use in the U.S. from 1935 to 1977, and continued to profit from their sale for years even as its officials knew the chemicals were polluting the environment, causing harm to people and wildlife, said Seattle City Attorney Pete Holmes.

“When the profit motive overtakes concern for the environment, this is the kind of disaster that happens,” Holmes said Tuesday. “I’m proud to hold Monsanto accountable.”

Seattle is the sixth major city in the West to seek cleanup damages from the company, joining San Jose, Oakland, Berkeley, San Diego and Spokane, which Holmes said gave him the idea to file the federal lawsuit.

The amount of damages requested isn’t specified and would be determined in the course of the lawsuit, said Laura Wishik, section director for environmental protection in the Seattle City Attorney’s Office.

Targeted is PCB contamination in 20,000 acres that drain to the Lower Duwamish, a federal Superfund site. Also at issue are areas that drain to the East Waterway, adjacent to Harbor Island, a separate Superfund site.

PCBs are the most widespread contaminant in Lower Duwamish sediments. City inspections have detected PCBs in 82 percent of samples of sediment in drainage pipes, according to the complaint.

Resident fish and shellfish in the Lower Duwamish Waterway are so contaminated by PCBs, the state Health Department advises there is no safe amount to eat — yet people keep right on fishing.