MANCHESTER — Attorneys argued Monday that owners of 236 properties near a former Amherst company should be allowed to join forces in a class action lawsuit seeking damages over suspected PFOA contamination.

“Here in the class defined, every single class member has suffered harm from contamination by chemicals released from a common source by the same conduct,” attorney Kevin Hannon said during a hearing in Hillsborough County Superior Court.

An Amherst family on Eastern Avenue filed two class action complaints in 2017 alleging that the Textiles Coated International facility in Amherst — which operated at 105 Route 101A from 1985 to 2006 — released toxic emissions from the plant into the air, soil, surface water and groundwater of the area.

Hannon is asking a judge to permit nearby residents to join in one lawsuit, versus going through individual trials.

One complaint seeks monetary damages for owners of 236 identified properties with private wells within three quarters of a mile from the TCI site and properties to the north along and within the area of Boston Post Road on the west; Cross Road through its easternmost intersection with Windsor Drive; and Waterview Drive.

A second complaint seeks medical monitoring services for those living in the area on properties meeting certain perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) levels.

A health advisory from the U.S. Environmental Protection Agency said studies on animals showed that exposure to PFOA and/or PFOS above certain levels “may result in adverse health effects,” including developmental effects to fetuses during pregnancy as well as certain cancers.

The state Department of Environmental Services is investigating several sites around the state, including the Saint-Gobain Performance Plastics site in Merrimack, where higher-than-allowed levels of contamination have been found.

Today, TCI operates a facility at 200 Bouchard St. in Manchester.

DES issued an administrative order dated March 27 ordering TCI to conduct stack emission testing of PFAS from one of its Manchester tower coaters.

The company is objecting to the order, according to DES spokesman Jim Martin.

“They do have some sort of treatment on their stacks in Manchester,” Martin said.

A TCI attorney declined to comment on the lawsuit.

TCI makes “high-performance fluoropolymer films, laminates and composites,” according to its website.

TCI officials suggested in court papers that there might be other sources for the pollutants in Amherst.

During the hearing, Hannon said the company didn’t investigate after learning of PFOA concerns in 2003.

“Even learning of PFOA concerns in late 2003, no investigation was started until 2016,” Hannon said.

Citing modeling done by state environmental officials, “Each individual modeling effort shows that there, TCI, is the center of release and the subsequent center of deposition of PFOA on to class properties,” Hannon said.

In 2016, the state DES adopted the EPA’s health advisory for PFOA and PFOS at 70 parts per trillion combined. DES is proposing new drinking water standards, including 38 ppt for PFOA, 70 ppt for PFOS and 70 ppt for combined PFOA and PFOS.

According to Hannon, of 147 homes tested, more than 17 homes recorded over 70 ppt. Those homes housed at least 31 adults.

Fellow attorney Paul DeCarolis said TCI connected 96 homes to Pennichuck Water at the state’s request.