Pollution Alters DNA in Mice, Study Finds
May 18, 2004
By THE ASSOCIATED PRESS
WASHINGTON - Breathing soot from factories or highways may
cause genetic damage that can be passed to offspring,
scientists have found in an experiment on mice.
It is unclear whether the pollution-damaged DNA harms
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," said Dr. Jonathan Samet of Johns
Hopkins University, who led a recent National Academy of
Sciences study of the issue. "The new work now adds another
area of potential concern."
Until 2002, there was little evidence that any air
pollutant might cause genetic damage that can be inherited.
That year, Canadian scientists placed mice downwind from
steel mills and tested their offspring. The males passed on
twice as many DNA mutations as did mice living in the
cleaner countryside. Those same researchers, who are from
McMaster University in Ontario, reported in the journal
Science last week that the cause of the mutations was
airborne particulate matter, or soot. It is emitted from
factories, power plants and diesel-powered vehicles.
In the latest experiments, the scientists 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 high-efficiency air filters to catch
Then, the mice were bred and scientists checked their
offspring for specific DNA mutations that are passed
through the father's sperm. The mice breathing filtered air
had mutation rates 52 percent lower than those exposed to
full-strength pollution, the scientists found.
The mutations measured are not linked to disease, but they
are similar to a type of DNA damage that is. Dr. James
Quinn, a McMaster biologist and the report's lead author,
said more research was needed to determine whether these
changes were a marker for potential health problems and
whether the mutations could be inherited, too.
Dr. Quinn said the study's practical value might lie in
what it showed about the effectiveness of air filtration.
Because particulates adhere to tree leaves just as they do
to filters, he said, the study may have implications for
policy-makers who must decide on road-building and
The Environmental Protection Agency already has ordered
tougher limits on ultrafine 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 parts of the country are not in
compliance with these rules.
Dr. Quinn said he did not know whether the particulates
themselves or toxic chemicals that attach to them damaged
the sperm. But one suspect is a group of
particulate-clinging chemicals, polycyclic aromatic
hydrocarbons, or P.A.H.'s, some of which are known to be
cancer-causing. Air samples showed daily P.A.H. exposure
near the steel mills was 33 times as high as in the
countryside. But HEPA filtering of the urban air blocked
most of those chemicals, the study concluded.