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29 May 2003
EPA Study Provides Evidence that Metal Particles May Increase Severity of
Asthma
RESEARCH TRIANGLE PARK, NC...Scientists at the Environmental Protection Agency
have identified metals as primary suspects in air pollution which may affect
the severity of pre-existing asthma in adults and children. This international
study, available online in Environmental Health Perspectives* is the first
to link human and animal data to show the possible role of metals in soot from
metal industries and coal combustion in aggravating asthma.
A recent epidemiology study by German scientists found children living in the
polluted city of Hettstedt had higher rates of bronchitis and allergic diseases
compared to a similar group of children living in the nearby city of Zerbst
where air pollution is comparatively lower. Scientists at EPA’s National
Health and Environmental Effects Research Laboratory in Research Triangle Park,
NC, used samples of fine particulate matter (PM2.5) taken from the two German
cities to investigate air pollutant components which may cause these symptoms.
In the study, scientists found that the amount of toxic metals in PM2.5 from
polluted Hettstedt was several times higher than PM2.5 from relatively pollution-free
Zerbst. Animals prone to allergic asthma had greater lung inflammation and
exacerbation of allergic symptoms after exposure to the particles from the
heavily polluted city compared to those exposed to particles from the less
polluted city.
The results also suggest that exposure to metal-rich particles exacerbate existing
asthma, but does not increase the incidence of new asthma. Lung inflammation
and function changes occurred when particles were administered to mice with
pre-existing allergy, but not when particles were given to mice just before
they were made allergic.
In 1998, the EPA and the German GSF (Research Center for Environment and Health)
began a collaboration to study problems related to environmental pollutants
and their impact on human health. The study is a culmination of this partnership.
A major strength of this study is that epidemiological and toxicological approaches
have been combined to give greater certainty on the health effects of PM2.5.
Allergic asthma is considered an epidemic in the United States and afflicts
an estimated 15 million Americans, including about five million children. Since
1980, the biggest growth in asthma cases has occurred in children under five.
The EPA’s Asthma Research Strategy identifies and prioritizes the research
needed to understand better the environmental factors that contribute to disease.
While studies that analyze relationships between medical records of populations
and environmental factors have established strong evidence that PM2.5 can exacerbate
asthma, more toxicological research is needed to identify responsible components
for health effects. Metals are under intense investigation as both epidemiology
and toxicology studies continue to document evidence of their detrimental health
effects.
For more information on EPA’s Asthma Research Strategy, visit the Web
site: http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=54825.
*Gavett, S. H., N. Haykal-Coates, L. B. Copeland, J. Heinrich, and M. I. Gilmour.
Metal composition of ambient PM2.5 influences severity of allergic airways
disease in mice. Environmental Health Perspectives doi:10.1289/ehp.6300. Available
at: http://ehpnet1.niehs.nih.gov/docs/2003/6300/abstract.html.
Editor's
note: A full copy of the report is available by fax or e-mail (PDF
format) to media at no charge. Go to www.ehponline.org/press,
call 919-653-2583, or e-mail ehollingshead@brogan.com.