Low blood lead levels in children linked to behavioral problems

New data published in JAMA Pediatrics suggest that even low blood lead levels in children can cause emotional and behavioral problems.

Jianghong Liu, PhD, of the University of Pennsylvania School of Nursing in Philadelphia, and colleagues evaluated 1,025 children aged 3 to 5 years from China to determine the effects of blood lead concentrations on behavioral and emotional problems.

Overall, the mean blood lead concentration was 6.4 mcg/dL. Ninety percent of participants had blood lead concentrations of ≤9.4 mcg/dL, 75% ≤7.5 mcg/dL, 50% ≤6 mcg/dL and 25% ≤4.6 mcg/dL.

Scores for emotional, anxiety and pervasive developmental problems were negatively affected by blood lead concentrations. Specifically, a 1-mcg/dL blood lead concentration increase led to increases of 0.322 on emotional reactivity scores, 0.253 on anxiety problem scores and 0.303 on pervasive developmental problem scores (P<.05).

At aged 4 years (P=.048) and 5 years (P=.04), blood lead concentrations increased behavior scores for internalizing problems among girls. These scores increased for boys at aged 5 years but decreased at aged 4 years.

After adjustment for child and family characteristics, increased odds for emotionally reactive problems (OR=1.1; 95% CI, 1.02-1.19), anxious/depressed (OR=1.12; 95% CI, 1.03-1.23), total internalizing problems (OR=1.1; 95% CI, 1.03-1.18), DSM-IV-oriented anxiety (OR=1.1; 95% CI, 1.01-1.19) and pervasive developmental problems (OR=1.16; 95% CI, 1.07-1.25) remained associated with blood lead concentration.

 “This study contributes further evidence that blood lead concentrations even below the CDC’s previously defined level of concern (10 mcg/dL) are harmful and that exposures now commonly encountered in China may have implications for children’s behavioral developments,” the researchers wrote. “As such, continued monitoring of blood lead concentrations as well as clinical assessments of mental behavior during regular pediatric visits may be warranted. Further examination is needed to more clearly delineate the biological effects of environmental lead exposure and resulting behavioral impairments among children and to assess the long-term clinical significance of these findings.”

Disclosure: The study was funded in part by the Jintan city government, Jintan Hospital, the National Institute of Environmental Health Sciences, the University of Pennsylvania Center of Excellence in Environmental Toxicology, and the Wacker Foundation. One researcher reports financial ties with the National Institute of Environmental Health Sciences.