Blood levels of lead below those considered elevated by the Centers for
Disease Control and Prevention still may negatively impact kidney function
in otherwise healthy adolescents, says a study in the Jan. 11 Archives of
Internal Medicine.
Researchers at the Johns Hopkins Children's Center in Baltimore gathered
data from 769 adolescents, ages 12 to 20, who participated in the Third
National Health and Nutrition Examination Survey from 1988 to 1994.
Nearly all of the participants had blood lead levels below 10 ug/dl (the
CDC's threshold for concern), with an average level of 1.5 ug/dl.
Researchers found that higher lead levels, which were still below 10 ug/dl
of blood, were consistently associated with a lower glomerular filtration
rate.
"There is a lot of accumulating evidence showing a role of lead [in kidney
disease]. ... But I was a little surprised that we saw the association in a
relatively small population of healthy kids," said Jeffrey Fadrowski, MD, a
pediatric nephrologist and assistant professor of pediatrics at the Johns
Hopkins University School of Medicine in Baltimore and an author of the
study (archinte.ama-assn.org/cgi/content/short/170/1/75/).
Adolescents with blood lead levels of 3 ug/dl or greater had lower
glomerular filtration rates than those with lead levels that were less than
1 ug/dl of blood. For each twofold increase in the amount of lead in the
blood, the kidney's filtration capacity dropped by 2.3 units in males and
3.3 units in females.
The link between higher lead levels and decreased kidney function persisted
even after researchers eliminated hypertension, which less than 5% of study
participants had, as a possible factor affecting kidney status.
The CDC recognizes that adverse effects exist at blood levels less than 10
ug/dl, but such levels cannot clinically be characterized as lead
poisoning, said Mary Jean Brown, chief of the CDC's Healthy Homes and Lead
Poisoning Prevention branch.
Dr. Fadrowski said more studies are needed to examine the possible impact
of environmental lead exposure on kidney function. Brown said more needs to
be done to eliminate lead in children's environments before they are
exposed.
"And we're moving in that direction," Brown said, citing legislation
approved in 2009 that reduced the permissible total lead content in
children's products, and the Clean Air Act, which has lowered lead
concentrations in the air.
The full and original article can be found here:
http://www.ama-assn.org/amednews/2010/02/01/prse0204.htm
