It's unclear exactly how many school gymnasium floors in New Jersey have the potential to emit toxic mercury vapor over time, or are already doing so.

But the state can be sure of one thing now: no future Schools Development Authority projects will include floors that contain a mercury catalyst, which can lead to harmful effects on humans and has already been recognized in several New Jersey instances.

The SDA, which funds and manages construction and renovation of schools in 31 New Jersey districts, announced it will be requiring an additional certification from manufacturers of rubberized and/or urethane floors that can guarantee the product is free of any mercury catalyst during manufacturing and installation.

The hazardous product would be used to help cure the floor. But as time goes on and small cracks form, mercury vapor can seep out from below. The rubber-like floors in question have been installed since the 1960s. Healthy Schools Now, part of the New Jersey Work Environment Council, said installation of this floor type has been documented as recently as 2006.

"This is a really great first step," Heather Sorge, campaign organizer for Healthy Schools Now, said of the SDA's move.

But the coalition is attempting to get an additional certification required for all rubber-floor school projects in the state moving forward, not just those in the 31 SDA districts.

In an April 2019 memo, the New Jersey School Boards Association said it has been informing its members about the issue for the past two years.

Sorge said no one knows how many of these floors exist or where they are located. A floor's date of installation, and even in the safety data sheets that come along with the floor, are not determining factors in identifying whether or not a floor contains mercury.

"These floors need to be tested," Sorge said. "The only way to ensure the safety of the students and the staff and the community is to make sure that the floors do not contain this mercury vapor."

For testing, a bulk sample would have to be sent to an accredited laboratory.

Mercury vapor can damage the central nervous system, kidneys, lungs, skin and eyes, the group said. It's especially harmful to young children whose bodies are still developing.

"New Jersey parents are thankful that the SDA is addressing the issue of mercury in our school flooring," Trisha Sheehan, a New Jersey resident and National Field Manager for Moms Clean Air Force, said in a news release. "New Jersey parents are deeply concerned that our schools and places of learning could be potentially poisoning our children. As a parent to school aged children, I need to know that when I send my kids to school every day, that I am not exposing them to potent toxins that could harm their health and impact their learning."

The issue came to light in New Jersey in 2017 when a Burlington Township school had to label its outgoing rubber floor as hazardous waste. Testing detected mercury before removal had begun, and additional tests found the problem had seeped into the concrete below.

Several contaminated floors were spotted in Gloucester County this spring, many of which are slated for removal this summer.

The issue is not unique to New Jersey. Floors in several states, including New York, have tested positive for mercury.

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Contact reporter Dino Flammia at dino.flammia@townsquaremedia.com.