MacArthur Airport in Ronkonkoma may be added to the Department of Environmental Conservation's list of state Superfund sites over fears that firefighting foam may have tainted the water.

The state says samples taken from a well in Bohemia show unacceptable levels of the chemical PFOS, which has been linked to cancers, thyroid and liver problems.

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The town of Islip says the foam is no longer being used at Macarthur Airport.

This is the third time in the past two years that chemicals linked to firefighting foam have been found in groundwater near Long Island airports. Environmental groups say they will likely be many more cases.

Officials from the state DEC say they are investigating the exact cause of the contamination and how far it spread.

According to the Suffolk County Water Authority, filtration systems prevented the chemical from getting into drinking water.

In a statement, the Town of Islip said it will fully cooperate with the DEC's investigation into the contamination.