Even low levels of lead in the blood can affect children's behaviors, a recent study shows.
Children ages 3-5 with an average of 6.4 micrograms of lead per deciliter of blood were more likely to have issues with anxiety, emotion and delayed social skills, according to a study published online June 30 in the Journal of the American Medical Association Pediatrics.
Research has shown that childhood exposure to lead — which often occurs through lead-based paint or dust — can affect a child's IQ and academic achievement, according to the Centers for Disease Control and Prevention. CDC adopted Advisory Committee on Childhood Lead Poisoning Prevention recommendations in 2012 that said 5 — not 10 — micrograms or more of lead per deciliter of blood is an unhealthy exposure.
While most research focuses on the link between lead exposure and IQ, there are few studies on the link between lower blood lead levels and child behavior problems, said senior study author Jianghong Liu, PhD, RN, FAAN, an associate professor at the University of Pennsylvania School Of Nursing. Research that does focus on low blood levels and behavior usually focus more on outward behaviors, such as hyperactivity.
“Identifying early health risk factors is an important first step in preventing behavior problems,” Liu told The Nation's Health.
The study looked at the blood lead-level concentrations and behaviors of more than 1,000 children from the China Jintan Child Cohort Study. Researchers looked at blood lead concentrations in children at age 3, 4 and 5 from November 2004 through March 2005. They also used two tests to analyze their behaviors and emotions when the children reached preschool. Researchers assessed child behavior in the last month of preschool at age 6 and cognitive abilities at ages 5 to 6 in the last year of preschool.
The study found children with low blood lead levels were more likely to be anxious, depressed, emotionally reactive or show pervasive development problems. Pervasive development problems include avoiding eye contact, being withdrawn and showing little affection, Liu said.
Average blood lead levels were higher for boys than for girls and increased with age, the study said. However, the link between blood lead level and behavior problems was stronger in girls than boys, Liu said.
Liu and researchers recommend that pediatric doctor visits include annual blood tests for lead and screening for behavioral problems in children who have been exposed to 5 micrograms of lead per deciliter of blood or more. Liu also said other countries, including China, should consider adopting a similar standard to CDC's of 5 micrograms of lead or more per deciliter being potentially harmful to children's development.
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