focus,” said Andrey Korchevskiy,
PhD, director of research and
development at Chemical and
Industrial Hygiene, Inc., in
Wheat Ridge, Colorado.
“In developed countries, the situation has been managed successfully, but
in the developing world, it has worsened,
with the size of contaminated territories
and the number of affected children increasing. This document is one of the
;rst attempts to provide perspectives on
international lead hazard recognition, exposure evaluation, prevention, and treatment,” he said.
In many developing countries, expo-
sures to lead in the environment during
childhood have been underestimated.; In
the regions investigated in the case study,
the mean blood lead levels (BLL) for chil-
dren exceeded 20 micrograms of lead per
deciliter (µg/dL), and in some instances, the
levels exceeded 100 µg/dL. The recent rec-
ommendation of the Centers for Disease
Control and Prevention (CDC) to reduce
the reference level for children’s BLL from
10 µg/dL down to 5 µg/dL re;ects an opin-
ion within the expert community that sig-
ni;cant health and behavioral problems
from lead in blood may result at even
lower levels than previously anticipated.;
According to; Korchevskiy, one of the
reference document’s three editors, along
with his colleagues James Rasmuson,
PhD, CIH, DABT, and Eric Rasmuson,
MS, CIH, the CDC’s recommendation
implies that the issue of lead contami-
nation will remain an important public
health priority in developed, as well as
developing, countries.
“The future of lead poisoning prevention lies in continuous international
collaboration and in a search for better
health and environmental solutions globally,” said Korchevskiy.
Lead contamination is particularly
dangerous because it targets a vulnerable
age group and its impact starts at very
low levels of exposure. Lead poisoning
can cause several hidden, non-speci;c
and irreversible neurological, neurobe-havioral, developmental, hematologic, renal, cardiovascular, immunological, and
skeletal health problems.
NIST Researchers Develop
Environmentally Benign
Coatings To Reduce Fire
Hazards
The National Institute of Standards and
Technology (NIST) has developed ;re re-
tardant coatings that are environmentally
friendly. Applied to polyurethane foam,
the bio-based coatings greatly reduced the
;ammability of the common furniture pad-
ding after it was exposed to an open ;ame.
Peak and average rates of heat release – two
key indicators of the magnitude of a ;re
hazard – were reduced by 48 percent and
77 percent, respectively, the NIST team re-
ports in the journal Green Materials. “This
is the biggest reduction in ;ammability that
we have achieved to date,” said team leader
Rick Davis. The all-natural coatings out-
perform other promising experimental ;re-
retardants that the NIST researchers have
devised with their layer-by-layer assem-
bly method. But Davis said the bio-based
coatings must be applied more generously,
in stacks of about 20 layers as compared
with six or seven layers. Although still
under study, the all-natural formulations
might offer an alternative to existing ;re
retardants, including some that have been
linked to human health risks and environ-
mental problems. The new coatings use
negatively charged DNA molecules to link
two positively charged materials known to
enhance ;re resistance: montmorillonite, a
type of soft clay that forms tiny crystals,
and chitosan, a ;ber derived from the shells
of shrimp, lobsters and other crustaceans.
For its part, DNA, which was obtained
from herring sperm, may also confer added
protection because it bubbles and swells
when heated, protecting the material be-
neath. The team tested four different com-
binations of the three ingredients. In each
combination, clay, chitosan and DNA were
ordered in a speci;c arrangement and then
stacked 20 to 30 layers high. Of the four,
the best candidate for a bio-based ;re retar-
dant, according to the researchers, appears
to be 10 repeating bilayers of chitosan
overlain by a mixture of DNA and mont-
morillonite. Besides providing the highest
level of ;re protection, the bilayer arrange-
ment “is likely to be easier, faster, and less
expensive to fabricate” than the other com-
binations, the team reports. However, this
coating increased the weight of the foam
by 16 percent. A lighter alternative, which
provides only slightly less ;re protection, is
a coating that features ;ve repeating four-
layer stacks, each consisting of chitosan,
DNA, chitosan, and clay. This arrangement
increases the foam’s weight by 5 percent.
“Both recipes are great candidates” for
environmentally benign ;re-retardant coat-
ings, the team said. Ongoing research aims
