Even Low Blood Lead Levels Linked to Child Behavioral Problems: Study

New research suggests that even preschoolers who only have low levels of lead found in the blood face an increased risk of behavioral and emotional problems, adding to concerns about the potential impact of lead poisoning on children.

In a study published online by the medical journal JAMA Pediatrics late last month, researchers found the level of lead exposure that may cause problems for children is much lower than previously believed.

Pennsylvania researchers tested the blood lead levels of 1,300 children in Jintan, Jiangsu province of China, who were between the ages of three and five. Children had an average blood lead concentrations of 6.2 micrograms per deciliter (mg/dL) of blood. Children with 7.5 mcg/dL of blood lead levels were in the 75th percentile and those with 9.4 mg/dL were in the 90th percentile.

Dr. Jianhong Leu, of the School of Nursing at the University of Pennsylvania, Philadelphia, and the team of researchers, used teacher-reported behavioral assessments to determine children’s scores.

The Chinese versions of the Child Behavior Checklist and Caregiver-Teacher Report Form were used when children were six years old.

Researchers found a one mcg/dL increase in blood lead concentrations resulted in an increase in emotional reactivity, anxiety problems and an increase in behavior scores concerning pervasive developmental problems.

They also detected a significant association between high blood lead concentrations and the number of teacher-reported behavioral problems, especially in older girls.

Links Between Lead Levels and Behavior

It is widely accepted that exposure to lead as children can result in behavioral and emotional problems. However, those effects are typically seen at higher levels. This study’s findings suggest behavior and emotional problems can be affected by relatively low levels of lead exposure, and increase with rising blood lead levels.

Children tested in this study showed signs of being anxious, depressed or aggressive and were scored based on those symptoms.

The children with even low blood lead levels were more likely to internalize behavior problems like anxiety and depression, along with externalizing problems, outcomes expected by researchers at higher lead exposure levels.

Researchers say young children are particularly vulnerable to the toxic effects of lead exposure. Exposure to lead can affect children’s developing nerves and brains, leading to behavior and emotional effects.

A study published in May 2013 also concluded low levels of lead in the blood can affect a child’s school performance, effecting reading readiness for children entering kindergarten. Researchers found children with blood lead levels between 5 and 9 mcg/dL were 21% more likely to score below national benchmarks on reading readiness.

Another study published last August revealed that children with high levels of lead exposure are more likely to experience behavioral problems at school. Researchers from the University of Wisconsin-Madison’s Nelson Institute for Environmental Studies found children exposed to lead are three times ore likely to be suspended from school for discipline problems.

Lead occurs naturally in the environment, but human exposure is often caused from mining, burning fossil fuels and manufacturing. Other common sources of exposure include lead based paint, caulking and pipe solder in older homes. The Chinese often are exposed to lead from polluted air.

The U.S. Centers for Disease Control and Prevention (CDC) recently lowered the reference level for safe lead levels to five mcg/dL. Anything above this level is considered dangerous and warrants public health attention. As a result of the CDC prompted change, the number of children diagnosed with unsafe blood lead levels in the U.S. doubled, to more than half a million children.

Researchers warn that no level of lead in the blood is safe for children.