Tension slowly bubbled to the surface during a recent meeting with the state’s Health Department and parents of Bronx New School students. Nearly two years ago, those parents found out their children had spent several hours a day for up to six years in a toxic environment that went undetected by the Department of Education for nearly two decades.

After releasing a report saying students and staff at the Bronx New School (PS 51) were at a slightly increased risk for cancer due to exposure to trichloroeythylene (TCE), a known carcinogen found at 10 times the legal limit inside the building, Health Department officials were doing their best to allay parents’ greatest fears.

The report categorized the increased risk of cancer as “low,” which is higher than “minimal,” but lower than “moderate” or “high.” There were levels found below the surface of the school that were 10,000 times the legal limit.

“The risks [for cancer] really do appear to be quite low,” said Thomas Johnson, a toxicologist with the Health Department, during the meeting at St. Philip Neri Parish on the Grand Concourse in Bedford Park, just blocks from the old PS 51 building at 2300 Jerome Ave.

But several parents weren’t interested in playing the percentages.

“It seems a little flippant to say, ‘actually this is quite low,’” said Laura Klein, a parent of a former PS 51 student, adding that there was no way for them to predict how the exposure will affect individuals.

Klein said she would “like to see some organized way of gathering” and tracking health information about students who attended the school. The term used for this is called “medical monitoring” and it’s been implemented among former teachers at the school as part of deal between the powerful teachers union, the United Federation of Teachers, and the DOE.

(At least one former teacher is suing the DOE after losing her baby during her time at the school. The Health Department’s report said babies born from women who worked at the school were at a “moderate” risk for heart diseases.)

But the DOE has not agreed to medical monitoring for students. Department officials have told parents they would not discuss the possibility until seeing the report, which was released two weeks ago.

Many parents have organized through the Northwest Bronx Community and Clergy Coalition into an advocacy group called PS 51 Parents United. They are pushing the DOE for medical monitoring and for an end to the so-called “leasing loophole,” which allowed the school to remain open in a contaminated building for nearly two decades.

The DOE is not required to do a full environmental review of a building when it is first leased. It is only when the lease is up for renewal, as it was at the PS 51 building in 2011, that an extensive environmental review, including checking toxicity levels, is required.

(Before becoming a school, the former PS 51 building housed an automotive garage and, most recently, a lamp manufacturer called Nessen Lamps. From 1982 to 1987, Nessen was listed on a government database as a manufacturer that used hazardous materials.)

Parents also remain upset that it took months for the DOE to inform parents of the high levels of TCE at PS 51. Readings were taken on January 22, 2011, but parents and students were not told until July of that year, after the school year was over.

Many former students and parents still have yet to be notified. The DOE says it has compiled a list of 2,400 former students, but many parents in attendance said they had not received a letter, despite living at the same address as when their children went to the school. One parent said she received a letter for another former student who never lived there.

Though parents had technical questions for the Health Department — including the questionable accuracy of the readings and the report’s findings — their frustration ultimately kept being redirected toward the DOE, who had sent a representative to the meeting, Elizabeth Rose, the chief of staff for the division of operations.

Rose, who sat in the audience with two other staff members, was reluctant to speak up until the crowd continued to stare and direct questions at her. At one point, former student Lelanie Foster, 26, stood up and asked Rose directly: “Why are you here?”

Finally, she stood up and said the DOE was here because it was invited and it wanted to continue its “dialogue with the community.”

Parents weren’t satisfied with Rose’s answer, but many said it helped to receive some re-assurance that the risks weren’t dire from the Health Department’s report.

“It wasn’t a total whitewash,” said Alan Gary, a parent of a former student who is working with PS 51 Parents United, about the report and question-and-answer session. “They offered some information. But they’re not going to give us all the ammunition to sue the city. There is only one agency that is truly responsible here and that’s the DOE.”

Gary said the next goal is to get into the room with Schools Chancellor Dennis Walcott and demand accountability.

He added that the report didn’t make him any less worried about the potential for illness down the road for his son, who remained in the school for the months between when the first readings were made and when the DOE shuttered the school.

“But that’s what I tell my son to make him feel better,” he said.