From: RustyBullethole, [EMAIL PROTECTED]
Genetic factors determine lead levels in body
By Anne Harding
NEW YORK, Nov 03 (Reuters Health) - Too much
lead in the body is bad news, but a new report suggests
that certain genetic variations may determine how the
toxin is distributed in an individual's body.
Dr. Brian S. Schwartz of the Johns Hopkins School
of Hygiene and Public Health in Baltimore, Maryland and
colleagues found that variations in two genes, ALAD and
VDR, affected three measurements of body lead levels in
people exposed to the metal.
The researchers checked levels of lead in the
blood and bone, as well as how much lead people excreted
after being given a chelating agent--a substance that
removes lead from the body.
The investigators found that those with the ALAD2
version of the gene had higher blood lead levels than
those with the ALAD1 version of the gene. What's more,
those with the VDRB gene version had higher levels in
the blood and bone, as well as higher levels of
chelatable lead compared to those with the VDRb version
of the gene.
The study included 798 workers from the Republic
of Korea who were exposed to lead on the job, according
to a report in the October issue of Environmental
Health Perspectives.
However, it is not clear if the gene variations
are harmful or helpful, said Schwartz, an associate
professor of environmental health sciences.
"We're not exactly sure yet which gene is better
or worse for health," Schwartz told Reuters Health. The
researchers are now looking at how the lead affected
the health of the workers.
Lead can be absorbed into the body through the
skin, lungs or digestive tract and can damage the brain,
nerves, kidneys and other organs. Most of the metal ends
up in the bones, but it can also bind to red blood cells.
Lead that is removed from the body by chelation comes
from soft tissues and organs, where it can do the most
harm.
Schwartz noted that the higher blood levels seen
in people with the ALAD2 gene may actually be protective.
While people with ALAD2 have higher blood lead
levels, he said, this may mean that the lead is bound
in higher quantities to the red blood cells and thus is
less likely to migrate to the organs.
"Recent data suggest that high blood levels are
probably good because it keeps the lead out of the
target organs where it can cause problems," Schwartz
explained.
Schwartz pointed out that his findings are
relevant to the United States as well as South Korea.
"We have lots of people exposed to lead in the
workplace in the United States," he said, for example
in industries such as battery manufacturing. Schwartz
and his colleagues conducted the study in South Korea
because, he said, no US employer would permit similar
research.
"It's becoming increasingly difficult to do
occupational health research in this country, especially
trying to figure out the health effects of chemicals,
because of concerns by employers about litigation," he
explained.
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