Air Pollution Linked to Genetic Mutations
By THE ASSOCIATED PRESS/NY Times Science Section
Published: May 14, 2004
WASHINGTON (AP) -- Breathing soot from factories or highways may cause
genetic damage that can be passed to the next generation, scientists
found in an experiment performed on mice.
No one yet knows if people could inherit pollution-damaged DNA that
harms their health. But the discovery comes as scientists already are
calling for more research into the dangers of particulates --
microscopic soot particles linked to asthma, heart disease and other
health problems.
``At the moment, we are grappling with the fact that even though the
air is visibly cleaner, we're still finding adverse health effects''
from particulates, said Dr. Jonathan Samet of Johns Hopkins University,
who headed a recent National Academy of Sciences probe of the
pollutant.
``The new work now adds another area of potential concern'' because of
the implications for future generations, he said Thursday.
There had been little evidence that any air pollutant might cause the
kind of genetic damage that can be inherited -- until Canadian
scientists in 2002 housed mice downwind from steel mills and tested
their offspring. The males passed on double the DNA mutations as mice
living in the cleaner countryside.
Those same researchers from Ontario's McMaster University are reporting
in the journal Science that they've found the culprit: airborne
particulate matter, better known as soot. It is commonly emitted from
factories, power plants and diesel-powered vehicles.
In the latest experiments, biologist James Quinn and colleagues housed
two groups of mice near the steel mills for 10 weeks. One group
breathed outside air; the other was housed in a chamber equipped with
HEPA filters -- high-efficiency air filters designed to catch
microscopic particles.
Then, the mice were bred and scientists checked their offspring for
specific DNA mutations that are passed through the father's sperm.
The experiment showed mice that breathed filtered air had mutation
rates 52 percent lower than the mice exposed to full-strength steel
mill pollution.
The specific sperm changes measured aren't linked to disease, but
they're similar to a type of DNA damage that is. Quinn said more study
is needed to see if they're a marker for potential health problems and
whether pollution-spurred mutations in disease-causing genes could be
inherited, too.
Regardless, Quinn said the study's practical value may be that it
demonstrates the effectiveness of air filtration. The HEPA filters
blocked particulates, and nature does the same thing -- particulates
adhere to tree leaves -- which has implications for policy-makers who
must decide on road-building and tree-cutting projects, he said.
Tiny enough to be inhaled deeply into the lungs, these particulates
enter the bloodstream and move through the body. If they can make it
all the way downstream to sperm-forming cells, ``that would be quite a
remarkable sequence'' -- one that needs confirmation, cautioned
Hopkins' Samet.
And the potential for affecting future generations makes it ``both a
public health issue and an issue for the ecosystem,'' he said.
The Environmental Protection Agency already has ordered tougher curbs
on ultra-fine particulate pollution because of concern about how it
affects the elderly, children and people with respiratory illnesses. In
December, the agency plans to announce which areas of the country
aren't in compliance.
Quinn couldn't say if the particulates themselves or toxic chemicals
that attach to them damaged the sperm. But one suspect is a group of
particulate-clinging chemicals called polycyclic aromatic hydrocarbons,
or PAHs, some of which are known to be cancer-causing.
Air samples showed daily PAH exposure near the steel mills was 33 times
as high as in the nearby cleaner countryside, but HEPA filtering of the
urban air blocked most of those chemicals as well, the study concluded.
Charles A. Miller III, Ph.D.
Environmental Health Sciences Department
Room 374 J.B. Johnston Bldg.
Tulane Univ. School of Public Health and Tropical Medicine
1430 Tulane Ave.
New Orleans, LA 70112
504-585-6942, rellim at tulane.edu
Web page: http://home.bellsouth.net/p/PWP-chuckmiller
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