New Jersey's Department of Environmental Protection has identified polluted groundwater near 60 day-care centers and has ordered immediate testing or other proof to determine whether children are exposed to toxic vapors or drinking water.

In the nine months since DEP inspectors discovered Gloucester County's Kiddie Kollege day care, where children were playing in a mercury-polluted former thermometer factory, DEP officials have reviewed the locations of hundreds of child-care centers to see whether others are on or near known contaminated sites.

About 700 day-care centers throughout the state, DEP found, were within 400 feet of polluted sites. Kiddie Kollege was ordered shut and an unknown number of others closed voluntarily as DEP inspectors fanned out and ordered testing whenever potential dangers were found.

Last week, DEP quietly ordered owners of 60 contaminated properties - mostly gas stations or manufacturers with leaking tanks - to test neighboring day-care centers' indoor air and drinking water for benzene, a cancer-causing chemical, and for other toxic substances. If the owners can show that the underground contamination is spreading away from the day-care centers, they may not have to take samples.

The DEP letter was sent to the owners of properties known to be polluted with high levels of dangerous volatile organic compounds that are within 400 feet of day-care facilities. Polluted groundwater can cause dangerous vapors to seep into buildings.

John Brennan, an environmental consultant, said DEP gave his clients three days to acknowledge the new order and 14 days to submit a remediation plan and work schedule.

They were also instructed to treat any problems - which could include installing an expensive air-vent system - or face penalties.

"The vapor testing has become the imminent thing," Brennan said.

DEP wouldn't disclose the names of the child-care centers or the 60 contaminated sites.

"It wouldn't be fair to single them out when they have not been identified as the source of a problem in a child-care center," said Larry Hajna, DEP spokesman.

For Bill Wolfe, an environmental watchdog and former DEP adviser, the latest order for vapor testing is vindication. Last month, he urged Gov. Corzine to veto parts of a post-Kiddie Kollege bill - it was designed to protect day-care children and schoolchildren from environmental dangers - because it did not require immediate indoor-air testing. The new law requires day cares to conduct air testing when renewing their licenses from the state Department of Children and Families.

Wolfe says DEP should also order indoor-air testing in houses and commercial buildings near polluted groundwater.

"If there's 60 day cares being impacted, think how many more homes and businesses - probably several hundred or thousands - that could be impacted," he said.

The children who attended Kiddie Kollege before it closed in July were found to have elevated levels of inhaled mercury in their bodies. Later health checks showed the levels had dropped. Health officials said the children should suffer no long-term health effects.

Ronald T. Corcory, an assistant DEP director, said the new tests ordered by his department are part of DEP's continuing effort to protect children from contaminants. He said he doubted the testing would uncover any unknown problems. Tests were ordered only as an "extreme precaution," he said.

"What we're focusing on is that no one in the building is breathing contaminated air, drinking contaminated water or playing in a contaminated area," Corcory said. "The whole purpose is so that we don't have another Kiddie Kollege."

Contact staff writer Jan Hefler at 856-779-3224 or jhefler@phillynews.com