TRENTON — Fears are growing in New Jersey over how much lead is in school water.

Newark, the state's largest district, revealed last month that half its aging buildings contained lead-tainted water. But concerns may only grow if state lawmakers pass a bill requiring all schools to test their water.

In New Jersey, just a fraction of schools and day care centers are required to check drinking fountains and sink water for lead, a toxin known to limit a child's development. Federal law requires testing only in schools that run their own water systems, opposed to those hooked up to a larger utility.

These schools represent only about 1 of every 10 schools in the country. And since 2013, 278 school water systems nationwide have exceeded federal lead standards, according to an Associated Press analysis of data from the U.S. Environmental Protection Agency.

In New Jersey, about 5 percent of the state's schools and day care centers are required to report lead levels to the EPA. And since 2013, nearly 20 of those roughly 200 schools took samples that show elevated lead levels.

Looking at all water systems, an Associated Press analysis of Environmental Protection Agency data found that nearly 1,400 that serve 3.6 million Americans have exceeded the federal lead standard at least once since Jan. 1, 2013. In New Jersey, 58 out of about 1,400 systems have had at least one over the limit test in the same time span.

Among the schools required to test is Delaware Valley Regional High School, which serves about 900 students in a rural stretch of New Jersey along the Delaware River in Hunterdon County.

The school's water comes from a well system. A 2013 routine test of the athletic trainer's sink found lead levels that were five times what the federal government considers cause for concern.

The problem was the water's acidity, which leached lead from soldering in the pipes, according to Business Administrator Teresa Barna.

That same year, the school installed a $10,000 system to better control the water's pH levels, she said. Since then it has spent another $10,000 a year on upkeep and extra testing. Barna said the school is now in compliance with EPA standards.

In Trenton, calls for more testing and remediation are growing — as are concerns about the cost.

Lawmakers who proposed testing in all schools have said it could cost about $3 million a year. Another proposal calls for spending another $20 million on water filters. A third bill would create a new recycling program for bottles and cans to generate extra revenue for lead abatement projects.

Gov. Chris Christie has said that any new lead mandates must be passed with responsible ways to pay for them.

We've been using the kids as the canary in the coal mine for too many years

"Maybe that's something the Legislature and I will decide to do," Christie told reporters Tuesday. "But I just want to caution everyone to not just have a knee jerk reaction to this."

In the meantime, urban districts such as Newark and Camden have been using bottled water to avoid aging pipes and infrastructure that leak lead. And Newark Mayor Ras Baraka has said that it could cost "billions" to fix the city's aging water system, which includes its schools.

Dr. Steven Marcus, executive director of the New Jersey Poison Information & Education System at Rutgers University in Newark, believes that testing water, as well as paint and soil, is far better than "using children as lead detectors."

He said that even the smallest amounts of lead in water can shave off IQ points.

New Jersey screens about 200,000 children annually. And although the number of kids with lead-tainted blood has plummeted, a few thousand still test positive each year, mostly from lead paint.

"We've been using the kids as the canary in the coal mine for too many years," he said.

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