The city of Spokane has sued Monsanto over pollution from PCBs in the Spokane River. Monsanto was the sole manufacturer of PCBs. They were banned in the US in 1979. Orin Blomberg/Flickr

The Portland City Council voted unanimously to file a lawsuit against agrochemical giant Monsanto.

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Portland plans to join six other West Coast cities — Seattle, Spokane, Berkley, Oakland, San Diego and San Jose — that have sued the company over toxic pollutants it produced.

Monsanto was the only company in the US that made Polychlorinated biphenals, or PCBs. The chemicals were once used as coolant fluids. Federal regulators banned PCBs in 1979. But the chemicals linger in the environment.

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In Portland, PCBs still contaminate the Willamette River and the Columbia Slough. And they're found in fish in the area.

Attorneys pitching the Monsanto #pollution suit say that by 1969, the company knew PCBs were found in shrimp, fish, oysters, and birds. — Amelia Templeton (@ameliaOPB) March 16, 2016

The attorneys pitching the case allege that Monsanto promoted its PCBs even though it knew they were contaminating food & wildlife. — Amelia Templeton (@ameliaOPB) March 16, 2016

Mayor Charlie Hales said the city has spent more than $1 billion cleaning up the Willamette.

"The citizens of Portland dug deep in order to pay for cleaning up our mess, and other businesses should be held to that standard,” Hales said.

In a written statement, a spokesman said Monsanto is not responsible for the costs associated with PCBs.

"Monsanto today, and for the last decade, has been focused solely on agriculture, but we share a name with a company that dates back to 1901,” the statement read.