A longtime city educator has mesothelioma — a type of cancer most often caused by asbestos exposure — and Philadelphia Federation of Teachers officials said Wednesday they are investigating a potential cancer cluster linked to widespread asbestos problems in schools across the district.

The teacher, who works at Meredith Elementary in South Philadelphia, also spent several years teaching at Nebinger Elementary, a few blocks from Meredith. The union declined to name the teacher, who was diagnosed recently.

The teacher has spent more than 30 years in Philadelphia classrooms.

As recently as 2015-16, Meredith was flagged by the district as a high-priority school for asbestos removal. Nebinger was one of 19 city schools where teachers and staff tested surfaces for asbestos fibers as part of The Inquirer’s “Toxic City: Sick Schools” series; the school was also one of seven designated for emergency cleanup by the district last year after The Inquirer discovered high levels of asbestos fibers in settled dust there.

Jerry Jordan, PFT president, said the problem is grave and extends beyond one school or teacher.

“This is a systemic issue with urgent needs that we must address,” Jordan said during a news conference at union headquarters Wednesday. “Disturbed asbestos has been observed and reported at schools across the district. The students and educators are literally risking death whenever they go to school — that is a shocking, shocking thing.”

Union officials said 175 schools, the majority of Philadelphia School District buildings, have asbestos that needs remediation.

Danielle Floyd, the district’s chief operating officer, said the school system believes that “our buildings are safe for students and staff to come to every day. We have a robust team that is addressing issues, concerns that come to us daily, hourly.”

But, Floyd said, the district’s buildings are old and in need of billions in repairs — much more than the school system has money to tackle. While it has completed more than 1,600 asbestos remediation projects in the last three years, more remain untouched.

“The reality is for us, we have to prioritize,” Floyd said during a news conference at district headquarters Wednesday. “We have to take a look at the information that we get, determine the appropriate course of action, and prioritize that against the other issues that we’re tasked to address.”

If an imminent threat is identified, the contaminated area is immediately shut down, sealed off, and remediated, said Brian Joseph, the district’s environmental director.

PFT officials and a coalition of state and local lawmakers called Wednesday for $100 million to fix all the lead and asbestos issues in the district’s 214 schools, problems brought to light in The Inquirer’s Toxic City series.

The district has stepped up its efforts to fix environmental hazards, but most of that work has been centered on lead-paint problems. The School District has spent $18 million to date on lead-paint stabilization, and the state has chipped in $12 million over the last two years.

The district has completed 29 asbestos remediation projects this year, it said.

No state money has been earmarked for asbestos projects.

Jerry Roseman, the PFT Health and Welfare Fund’s director of environmental science, said Meredith has several thousand square feet of known asbestos, in both floor tiles and pipe insulation, plus materials that are assumed to contain asbestos but have not been tested.

“Meredith is an old school and has a lot of asbestos material that is in student — and teacher — occupied areas,” Roseman said.

In the wake of the teacher’s diagnosis and out of “an abundance of caution,” Joseph said, the district is speeding up its timeline and will soon perform an environmental assessment at Meredith, one of two visual inspections done per year. That’s separate from the more comprehensive exam that is required by the U.S. Environmental Protection Agency to be performed at school buildings every three years.

“We are all saddened by the reports of the teacher with the illness,” Joseph said.

The Inquirer has identified the teacher, who is represented by attorney Benjamin Shein, but is withholding her name at her request.

“The students are only trying to learn and the teachers are only trying to do their jobs and educate the children in the city of Philadelphia, and little do they know that they are breathing in poison — day in and day out,” Shein said.

Roseman said that while Meredith was among the district’s highest-priority schools for asbestos removal, it was not “the worst of it.”

Last year, Roseman and a team of environmental experts visited Nebinger in response to The Inquirer’s testing and were alarmed by the amount of damaged asbestos they found in a basement classroom.

State and local officials said they had no plan to come up with the $100 million, but Jordan and others said most of the onus should fall on the state.

The Meredith teacher’s recent cancer diagnosis was not a call to action but a call to crisis, the officials said.

“You have children in grade school,” said State Sen. Tina Tartaglione (D., Phila.). “Their lungs are still developing and they are exposed to asbestos.”

Jordan acknowledged there was no definitive link between the teacher’s diagnosis and her work environment, but he underscored that the teacher has spent her career in buildings with known asbestos problems.

As schools across the district hold back-to-school nights, parents are likely to have questions about environmental hazards at their schools. Councilwoman Helen Gym said the district “needs to do a better job of communicating with our families about what’s going on — the fact that we live in a toxic city.”

Outside Meredith after Wednesday’s back-to-school night there, parents said they were upset over the teacher’s diagnosis and worried for the health and safety of their children and the school’s staffers.

“It’s a serious matter,” said David Krupp, whose son is first grader at Meredith, at Fifth and Fitzwater Streets. “Schools should be safe places to learn and play.”

Erica Litke, who has two sons at Meredith, said the school community is devastated by the teacher’s health condition. “I’m heartbroken,” she said.

Litke and other parents, however, said they wanted more detailed information about the potential toxic risks in their schools.

“The district has not been very forthcoming," she said. “I wish that district officials and environmental experts would meet with the parents and give us details so we’re fully informed. Not sound bites, but real and detailed information.”

Emily Carter Paulson, a surgeon who has two children at Meredith, said she worried about the teacher but “we have to be incredibly careful before jumping to conclusions over one person. I need more data. We don’t know what we don’t know.”