Lead Exposure Unhealthy at Any Level
Study finds declines in kids' IQ even at amounts now considered safe
FRIDAY, July 15, 2005 (HealthDay News) -- There's no safe level of lead in children's blood, according to an international study that found that children exposed to the toxin suffer substantial intellectual impairments, even at exposures far below levels currently considered harmful.
"The study indicates there is no threshold for the adverse consequences of children's exposure to lead," study lead author Dr. Bruce Lanphear, director of the Children's Environmental Health Center at Cincinnati Children's Hospital Medical Center, said in a prepared statement.
"We found evidence of intellectual impairments among children with blood lead levels below 10 micrograms per deciliter, the level currently considered acceptable by the Centers for Disease Control and Prevention. The study indicates that the action level set by the CDC isn't adequate to protect children," Lanphear said.
The researchers analyzed data from 1,333 children around the world tracked from birth or infancy until they were 5 to 10 years old.
Of the children in the study, 244 had blood lead levels of 10 micrograms per deciliter or less, while 103 children had blood lead levels of 7.5 micrograms per deciliter or less.
Lanphear's team also found that intellectual impairments caused by low levels of lead exposure are proportionally greater than those found in children with higher levels of lead in their blood.
For example, at the 10-microgram exposure level, the researchers estimate that children lost an average 3.9 IQ points compared to children with exposures of 2.4 micrograms. Raising exposure from 10 micrograms to 20 caused another 1.9-point drop in IQ, while the increase from 20 micrograms to 30 micrograms led to another 1.1-point decline.
The study concluded that even environmental lead exposure in children with blood lead levels below 7.5 is associated with intellectual impairments.
"The results of this pooled analysis underscore the increasing importance of primary prevention of childhood lead exposure," Lanphear said. "Collectively, this international analysis and other data provide sufficient evidence to eliminate childhood lead exposure by banning all nonessential uses of lead and further reducing the allowable levels of lead in air emissions, house dust, soil, water and consumer products."
The study appears in the July issue of the journal Environmental Health Perspectives.
The American Medical Association has more about lead exposure.