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Lead, language and substance use

How lead exposure in children leads to substance use by adolescents.

Despite efforts in the United States to reduce lead exposure, it is still prevalent. Lead can be found in jewelry, paint, clay pots, water pipes and much more. Whether it is breathed-in, swallowed or absorbed, exposure to lead particles can cause a number of serious health issues and is especially harmful for children. In 2012, the CDC lowered its “blood lead level of concern” due to a growing number of scientific studies that show that even low blood lead levels can cause lifelong health effects.

While elevated lead levels in children are a persistent public health problem, few group studies have examined the association of childhood lead levels with substance use in adolescence. A team of researchers, led by Meeyoung O. Min from the University of Utah’s College of Social Work, found there is a link between elevated blood lead level in preschool years and adolescent substance use and substance-related problems. The study was recently published in the journal, Environmental Research.

“The U.S. has done a lot to reduce lead from things like paint and gasoline over the last several decades, but it is still very prevalent—especially in urban areas,” said Min. “I wanted to find out whether or not lead impacts substance use and if it does, how it does.”

The 265 participants in the study were a subsample of a prospective birth cohort study on the developmental effects of prenatal cocaine exposure in the Midwest United States. The sample included primarily African Americans of low socioeconomic status from urban neighborhoods. Their blood lead levels (BLL) were assessed at age four, IQ at age 11, language skills and externalizing behavior at age 12 and substance (alcohol, tobacco, marijuana) use and substance use-related problems at age 15.

“It’s very rare to be able to see the span from childhood to adolescence,” said Min. “We had a rare opportunity to see the effects of lead across development stages and look at the whole span of its impacts.”

The researchers found that IQ is not related to substance use, but language skills and externalizing or aggressive behavior was. By adolescents, about 31% of the participants used tobacco or marijuana, 40% used alcohol and 23% reported experiencing substance use-related problems at an average age of 15.7. Min defines substance use-related problems as things such as constant desire for alcohol or drug, mood swings, drunk driving, missing school and relationship issues related to substance use.

In addition, a significant indirect association of blood lead levels, via childhood language skills, with substance use-related problems was found, identifying a risk process leading to adolescent substance use-related problems.

“It was really interesting to me to find that poor language development at age 12 is related to substance use problems,” said Min. “In the criminal justice system, language ability is a big factor because offenders cannot always express what happened in order to defend themselves. It’s more well-known that children with behavior problems tend to have more substance use issues, but I think knowing poor language skill as a risk factor adds a new, different element.”

Min hopes their findings may encourage parents, educators and health care providers to conduct early screening and intervention for language impairment which may reduce substance use-related problems. Continuing to reduce lead levels, Min said, is also critical to improved public health.

“Especially through water pipes and soil, lead is still prevalent, and it disproportionately impacts those living in low-income, urban neighborhoods,” said Min. “And we really need to provide language support for those children who are at-risk for lead exposure when they are young to prevent further escalating the likelihood of lifelong psychological, social and health problems.”

Co-authors of the study include Barbara A Lewis, Department of Psychological Sciences at Case Western Reserve University; Sonia Minnes, Jack, Joseph and Morton Mandel School of Applied Social Sciences at Case Western Reserve University; Kwynn M. Gonzalez-Pons, College of Social work at the University of Utah; June-Yung Kim, Department of Social Work at the University of North Dakota; and Lynn T. Singer, Departments of Population and Quantitative Health Sciences, Psychological Sciences, Psychiatry and Pediatrics at Case Western Reserve University.