New Hampshire filed a lawsuit Tuesday against the agrochemical giant Monsanto over what it says has been widespread PCB pollution in the state that has fouled waterways and found its way into the wildlife include seals, loons and fish.

The state alleges Monsanto and two companies that used to be part of Monsanto, Solutia Inc. and Pharmacia LLC, are responsible for contamination of public property as well as water and other natural resources. It also alleges in the complaint filed in Merrimack Superior Court that the PCB contamination is much more widespread than previously thought and that the companies knew of the dangers for decades but failed to warn the public.

PCBs, or polychlorinated biphenyls, are toxic industrial chemicals that have accumulated in plants, fish and people around the globe for decades. PCBs were used in many industrial and commercial applications, including in paint, coolants, sealants and hydraulic fluids. Monsanto, based in St. Louis, produced them from 1935 until 1977, two years before they were banned by Congress.

“Those who harm public resources must be held accountable. That is why we are taking this action today,” Attorney General Gordon J. MacDonald said in a statement Tuesday. The state did not ask for a specific amount in damages, only saying the amount should compensate for the damage caused by the PCBs and the cost of investigating and remediating the contamination.

Citing internal documents, the state says companies continued selling PCB mixtures even though they knew the compounds would lead “to contamination of human food (particularly fish), the killing of some marine species (shrimp), and the possible extinction of several species of fish-eating birds.”

The state did not say when the contamination in New Hampshire occurred or when the companies failed to warn the public. It did not specify what remedies it was seeking.

“As an environmental engineer I spent many years cleaning up PCB contamination, and I know firsthand the costs these efforts can place on individuals and communities," Republican Gov. Chris Sununu said in a statement. "By filing this lawsuit, we will ensure that polluters are held accountable and that our state will obtain the financial resources necessary to remedy the harm that PCBs have caused to our environment.”

Bayer, which bought St. Louis-based Monsanto in 2018, said in a statement that is reviewing the lawsuit but believes it is without merit. The other two companies did not respond to a request for comment.

“Monsanto voluntarily ceased its lawful manufacturing of PCBs more than 40 years ago, and never manufactured, used, or disposed of PCBs nearby or into New Hampshire’s waters, and therefore should not be held liable for the contamination alleged by the state,” the company said. "Where it has been determined that that cleanups are necessary, federal and state authorities employ an effective system to identify dischargers and allocate clean-up responsibilities. Litigation of the sort brought by the state risks undermining these efforts.”

The state said that PCBs have fouled about 81 square miles of the Atlantic Ocean and 46 other water bodies including stretches of the Souhegan River and Squam Lake where PCBs have been linked to a reduction in the loon population and found in the state's seal population. Testing in Squam Lake, the third largest lake in the state, found 160 PCB substances in fish in concentrations over 20 parts per billion. The state also found PCBs in loon eggs at the lake at over 10,000 parts per billion.

As a result, stronger advisories against eating fish have been issued for some waterways.

Similar lawsuits have been filed in other states related to PCB contamination. In June, Monsanto agreed to pay $95 million over PCB contamination in the state of Washington. Also, the company announced a $650 million settlement this summer with several California cities.