Three Philadelphia school teachers filed a proposed class action lawsuit on August 18 against the School District of Philadelphia, accusing the district of violating their First Amendment rights after they protested against asbestos in the school.

Ethan Tannen and Carolyn Gray, who are current teachers at Julia R. Masterman Laboratory and Demonstration School along with Karen Celli, who retired in June 2023, claim in a lawsuit obtained by ABC News that the school docked their pay for unauthorized absences after they assembled their workstations on the outdoor patio of the school amid concerns over asbestos in the facilities.

The complaint alleges that the district failed to provide complete information to teachers and parents about asbestos remediation efforts and potential dangers of asbestos at the school.

The school district marked the teachers as absent and docked their pay for Aug. 26 and 27, according to the complaint.

"Those teachers were not 'absent'. The district knew that and knew they were working," Mary Catherine Roper, an attorney who represents all three teachers, said to ABC News in a statement on Sept. 13. "The district wanted to stop the protest, so they threatened the teachers and then punished them. That violates the First Amendment."

The School District of Philadelphia told ABC News in a statement that they could not comment on pending litigation. They also would not elaborate on whether asbestos exists at the Masterman school.

The latest AHERA (Asbestos Hazard Emergency Response Act) report published for the Masterman school building, which is from the 2018-2019 school year, identified over 100 "confirmed" or "assumed" sources of asbestos in the building, according to the lawsuit.

"Asbestos is a naturally occurring fibrous material that has historically been used for many industrial and construction purposes," said Dr. Stephanie Widmer, an ABC News contributor and medical toxicologist, who was not involved in this case. "The material itself is very fire resistant and is a great thermal insulator, many houses built before 1980 contained asbestos. Since the discovery of negative health effects, 66 countries and territories have banned asbestos."

Though asbestos' use is now limited in the United States, it is not completely banned, Widmer said.

"Well established health risks of asbestos exposure include 'asbestosis', which is scarring of the lungs that results from inhaling asbestos fibers, and an aggressive form of lung cancer, Mesothelioma," Widmer said. "Asbestos is a known carcinogen."

According to Widmer, it is important to note that negative health effects from asbestos exposure don’t mount right away. It can take many years to develop illness.

The issue of asbestos in schools is one that the School District of Philadelphia has dealt with over the years. Two schools had to close last April due to concerns of the presence of the potentially hazardous mineral fiber.

Amid school closures, School District of Philadelphia superintendent Tony Watlington told ABC News in April that it would cost almost $5 billion to "fully repair and bring our buildings up to code."

"With decades of underfunding, the district has had to balance insufficient resources to work on our facilities and the need to deliver pressing educational services," Watlington added.

To curb the effects of asbestos in schools, Congress passed the Asbestos Hazard Emergency Response Act in 1986, ordering districts "to inspect their school buildings for asbestos-containing building material, prepare asbestos management plans and perform asbestos response actions to prevent or reduce asbestos hazards," according to the Brookings Institute, a non-profit public policy organization in Washington D.C.

Research has shown that lower-income and minority communities are disproportionally impacted by asbestos exposure, similar to other environmental pollutants compared to their wealthier, white counterparts because these groups are more likely to live in places or work in jobs that have environmental and occupational exposure.

"The class members suffered damage as a result of the district’s retaliatory actions in the form of a loss of First Amendment freedoms, lost wages and other employment benefits, and damage to their professional reputations from the discipline recorded in their employment records," according to the teachers' complaint.

According to the lawsuit, up to 50 teachers were improperly disciplined. The three educators are seeking an award of financial damages from lost wages, plus interest and an expungement of their employment records from the school district's disciplinary actions.

ABC News' Jade Cobern contributed to this report.