The recent revelation that New York City has allowed children living in public housing to be exposed to toxic lead could have pronounced consequences for the schools those children attend.

The dangers posed by lead poisoning, which include behavioral problems and impaired brain development, are grave and long-lasting. But studies show these effects can be mitigated with swift, early treatment. Here’s what we know about the impact of lead poisoning on student learning — and about what the city’s education department says it is doing in response to the current crisis.

‘No safe level’

Lead exposure at home can typically be traced to paint, which was manufactured with lead until the 1970s. Children are exposed to it if they eat paint chips or inhale dust from those chips.

It also exists in water that flows through lead pipes and in soil, which young children can unintentionally eat, according to the American Pediatric Association.

There is no “safe” level of lead — any exposure can have negative effects on the body.

“Once it’s in the body, it’s very hard to get rid of it,” said Morri E. Markowitz, director of the Lead Poisoning Treatment and Prevention Program at Children’s Hospital at Montefiore in the Bronx.

The effects are multipronged. Physically, anyone exposed to a high amount of lead may feel abdominal pain and constipation, according to the Centers for Disease Control and Prevention. Hyperactivity is another symptom, tough to immediately notice in young children since it’s common for them to run around, Markowitz said.

Those exposed to high levels of lead may also feel mental and psychological changes: depression, irritation and a sense of distractedness.

Depending on the severity and length of lead exposure in a child, it can result in “quite debilitating” neuropsychological effects, according to Mt. Washington Pediatric Hospital in Maryland. That includes poor performance in school and problems in developing social relationships.

Lead exposure has also been linked to misbehavior in school.

The effects of lead exposure can be minimized if a child has a nutritional diet because their bodies will absorb less lead if they’re eating other essential metals that humans need, like calcium and iron, Markowitz said.

That’s one reason why lead exposure is more likely to affect children in poorer families — lack of access to adequate or healthy food.

And poorer families can face greater obstacles avoiding led at the source, either because of a financial barrier or if the problem exists in subsidized housing.

Treatment is possible — if caught early

Lead poisoning was once thought entirely irreversible. But depending on the level of lead in a child’s blood, treatments do exist but vary, Markowitz said.

The first plan of attack is to get rid of the source so that the child is no longer ingesting lead. But this is a challenge for families who rely on public housing, where it’s beyond residents’ control to make such maintenance changes.

Another option is to reverse behavior -— stop the child from eating paint chips, for example, he said.

Children who test positive for a high amount of lead in their blood can also receive chelation therapy, Markowitz said. This medicine, taken orally, binds with the lead and leaves the body through urine.

But this medication is recommended for children who have blood-lead levels of 45 micrograms of lead per deciliter of blood or higher. A child’s blood-lead level is considered unsafe if it’s 5 mcg/dL or above, according to the Mayo Clinic.

Research has found that taking the extra step to curb children’s lead exposure even after it has happened — and monitoring their behavior and health — can actually help boost test scores.

A study published this year focused on a group of children with high lead exposure from Charlotte, North Carolina in the 1990s. They received coordinated interventions designed to reduce lead exposure, encourage  healthy habits, and provide information on nutrition, among other treatments.

For elementary and middle-school students, test scores went up moderately and they were suspended for fewer days when compared to children who didn’t get this help. The students who got treatment were also less likely to be cited for committing a crime in school. Such efforts are costly but they help avoid the need to address lead’s effects later on, which can be even more expensive.

More testing and education needed

Because of increasing evidence on lead’s negative impact on children’s development, many states have made it a priority to attempt catching lead exposure early — in part because blood tests, the easiest way to determine lead poisoning at present, typically only work for a few years after exposure.

“By the time you’re at school, the lead in the blood is gone — it’s gone elsewhere,” Markowitz said. Lead doesn’t sit “around in the blood for five years,” he said, but migrates to the bones or the brain, where lead can remain for two to three years, continuing to do damage.

That’s why — like many states — New York requires doctors to test young children for lead exposure, Markowitz said.

New York health care providers are required to test 1- and 2-year-olds for lead in their blood. They’re also supposed to assess children no less than annually for risk of lead exposure up to the age of 6 and to decide whether they need a lead blood test.

Despite these rules, reports have found that millions of children go without getting tested. In New York State, just 55 percent of children who were supposed to undergo testing actually got it, according to a Reuters investigation in 2016 — and those who are most at risk may be the least likely to get tested, owing to inadequate access to health care or lack of knowledge about lead dangers.

Other reasons might include children missing appointments, parents not following up on test referrals from doctors, or some doctors not ordering the tests — for instance if they’re unaware of the mandates.

One clear solution could be spreading more education and awareness to parents about the importance of catching lead exposure early. To date, the Department of Education has largely focused on the risk of lead in schools, sending letters to families about detailed lead test results within its buildings.

But students are most likely to be exposed to lead outside of school — even as children are bringing the impact of that exposure to classrooms, where it has the potential to undo schools’ best efforts to boost academic success. Schools thus have an invested interest in battling the perils of lead.

The city’s education department shared with Chalkbeat a letter parents have access to, with subsections that tell parents about lead’s health effects, where it can be found, and whether a child should be tested.

But given recent revelations about widespread exposure to lead in public housing, affecting some of the city’s most vulnerable populations of students, schools may need to join the battle to combat the severe danger that lead poses to students’ social and emotional health and academic prospects.

Department officials did not respond to a follow-up question: whether students are explicitly taught in class about the dangers of lead exposure outside of school.

But similar to other research, Markowitz and his colleagues conducted their own study and found that regular intervention, including improving nutrition and reversing behaviors that reduce lead exposure, can over time reverse lead’s effects on children’s cognitive functions.

“There is the possibility that the brain can get better,” Markowitz said.