Dozens gathered at the Mastics-Moriches-Shirley Community Library Tuesday for more information on water contamination in the area.

Organizations Water for Long Island and the Long Island Sierra Club have been working to inform residents who rely on private well water in an area that encompasses parts of Yaphank and Shirley. They say that contaminants called perfluorooctanoic acid, or PFOA, have seeped into the water supply and into private wells.

According to the Centers for Disease Control and Prevention, PFOA can cause growth and development issues and liver problems, in addition to affecting pregnant women and their unborn children.

Hydrogeologist Nicholas Valkenburg, who spoke at the meeting, warns that the contaminants won't go away without human intervention.

"Once they get into the environment, they don't degrade naturally, and they bioaccumulate in animals and in humans," he says, meaning the contaminants build up within people and animals exposed to them.

The state Department of Environmental Conservation has labeled the area a Superfund site because of hazardous waste found there. The source is the Suffolk County Firematics facility.

Water experts say the foam that was used at the firefighter training facility contaminated area wells with PFOA. And while the focus has been on residents who use well water, organizers at the meeting said they worry the contaminants can spread to an aquifer.

But the DEC says that residents connected to public water shouldn't worry because that water is tested regularly.

Anyone who gets their water from a private well can have it tested by the Office of Water Resources in Suffolk County, free of charge. Those with contaminated water can receive free bottled water for drinking.

In response to concerns about contaminants, the DEC has ordered the county to take water samples and provide a plan to clean it up.