A two-year investigation conducted by the news agency Reuters has revealed that even in states required to perform universal lead testing, kids face an increased risk of lead poisoning.

These states require lead testing beyond mandatory targeted screening for kids who are eligible for or enrolled in Medicaid, foreign-born children and those identified by the Centers for Disease and Control Prevention (CDC) as being at high risk for exposure to the toxic heavy metal.

The inquiry followed the lead epidemic in Flint, Michigan, in 2015 and eventually identified nearly 4,000 communities in the United States where children showed elevated levels of lead in their blood exceeding those seen in kids in that city. Like the children in Flint, most of these youngsters lived in disadvantaged areas.

In 1979, Herbert Needleman, MD, a pediatrician and researcher, published landmark findings that showed that inner- city Black children were exposed to lead levels five times higher than those found in mostly white suburban kids.

However, lead poisoning doesn’t discriminate. “While poverty remains a potent predictor of lead poisoning, the victims span the American spectrum—poor and rich, rural and urban, Black and white,” notes the Reuters report.

Needleman’s initial investigation and his follow-up studies showed that the metal’s effects—even at the lowest acceptable levels of exposure at that time—harmed the cognitive development, psychological and academic performance, IQ and behavior of children in cities throughout the country.

Experts agree that lead exposure can trigger a downward spiral. “The lower your IQ, the more trouble learning, the more likely you are to drop out of school, to be delinquent, to be incarcerated,” says Morri E. Markowitz, MD, the director of the lead poisoning treatment and prevention program at the Children’s Hospital at Montefiore in New York City, who was interviewed for the study.

When drinking water contaminated with lead threatened primarily kids in the inner-city and other residents in Newark, the situation drew comparisons to the problem in Flint. There, too, the ongoing crisis defies quick fixes.

Like officials in Flint, Newark authorities were finally forced to acknowledge the public health issue. They shut off school water fountains and ordered and distributed bottled water for residents to drink. But levels of lead in the water have remained high.

To address the problem, experts added special chemicals to the water supply. The presence of these corrosion inhibitors eventually creates a protective lining that coats the pipes and stops lead from leaching into the city’s drinking water.

But other sources of lead abound in soil, dust and air as well as in consumer products such as spices, toys, jewelry and supplements—many of them imported from foreign countries.

This is why the CDC recommends screening to protect children from lead poisoning. Such interventions can help parents, doctors, public health officials and communities identify the problem and take action earlier to reduce youngsters’ future exposure to the poison.