Elevated levels of a potentially cancer-causing substance have been found at two Nassau schools, and residents believe the Bethpage plume is to blame.

Radon was detected in the air in some rooms in at least two schools within the Bethpage School District. The district says it has been proactive with testing for the substance and performing remediation. JFK Middle School will be tested again this summer.

But residents like Michael Lynch suspect that the radon is linked to the toxic Grumman plume, which was the result of toxic dumping that took place as military production ramped up during World War II. It's continued to spread for decades.

"Should I be drinking my water?" questions Lynch. "Should I be going in my basement for the airborne chemicals that it might be putting into the air? Should I sell my house? Is this killing me?"

As News 12 has reported, the district started testing for radon after radium was detected in the groundwater monitoring wells under the high school and an elementary school.

Dozens of Bethpage residents have filed a lawsuit against the state DEC and the Navy. Attorney James Rigano says they want an investigation into the radioactivity in the groundwater and radon in buildings within the Grumman plume area.

"Why aren't we checking to see if the people are safe? And maybe they are, maybe they're not -- we just want an investigation," says Rigano. "We want the Navy to pay for it."

The DEC says it's unclear if the radon is connected to the plume. That remains under investigation.

News 12 reached out to the Navy for a comment to see if they'll test the entire area, but has not yet received a response.