A judge in the trial of a father and son accused of illegally dumping hazardous debris in and around Islip Town tossed out five felony counts Wednesday after prosecutors said they found an error in a state code listing for one of the contaminants.

Assistant District Attorney Mark Murray made the motion to dismiss the counts on the opening day of jury selection in the trial of Thomas Datre Sr. and his son, Thomas Datre Jr.

The pair are among six individuals indicted in December 2014 for their roles in the alleged scheme to dump contaminated debris at four Islip-area sites including Veterans Way, a six-home subdivision for returning veterans in the wars in Iraq and Afghanistan; Roberto Clemente Park in Brentwood; a private, 1-acre lot on Islip Avenue in Central Islip; and a sensitive wetlands area in Deer Park.

The felony counts tossed Wednesday each are related to cobalt, a metal found in the dumped debris that can cause asthma, pneumonia as well as cardiac and immunological disorders if inhaled.

The Datres still face several felonies, including charges related to contaminants like dieldrin as well as criminal mischief.

The father and son are accused in the indictment of being “recklessly engaged in conduct which caused the release to the environment of a substance acutely hazardous to the public health, safety or the environment, to wit: cobalt.”

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In a Central Islip courtroom Wednesday, Murray told Judge Fernando Camacho prosecutors “have not been able to satisfactorily resolve what appears to be a transcription error in the New York code” related to cobalt’s listing as a hazardous substance.

Murray said prosecutors consulted with officials in the state Department of Environmental Conservation and other experts but “we have been unable to reach a definitive resolution.”

Robert Clifford, a spokesman for the Suffolk district attorney’s office, said in an email Wednesday night “there is an issue as to how cobalt is numerically identified” in the New York state code and its listing is identical to another listed hazardous material.

The correct identifying number for cobalt does not appear in the state code section so “therefore, due to this discrepancy, the People move to dismiss the cobalt counts in the interest of justice,” Clifford said.

Clifford did not respond to questions about when the discrepancy was discovered. The DEC did not respond to a request for comment.

The attorney for Datre Jr. and his corporations, Kevin Kearon of Garden City, said the matter was discussed earlier in chambers and off the record and he requested an explanation on the record and in writing, “in order for us to evaluate if there were irregularities in front of the grand jury.”

Kearon said “we regard that as a potentially consequential matter. My client may have been prejudiced. There may have been improper information, false information.”

The five felonies each carried a potential sentence of 1 1⁄3 to 4 years in prison