mill smoke can trigger mutations
United Press International
Ontario-- Steel mill smoke can mutate DNA, leading to
genetic damage that could persist for generations, Canadian
scientists reported Monday.
The new data in mice suggest wildlife and the hundreds
of thousands of people who live or work near steel mills
worldwide could experience higher-than-expected rates
of inherited genetic diseases.
is somewhat surprising and concerning is that heritable
DNA mutations were significantly elevated after only 10
weeks of ambient air exposure," lead researcher Christopher
Somers, an applied ecologist at McMaster University, told
United Press International.
The researchers now are conducting experiments to see
if filtering chemical-laden soot can dampen its mutative
the results are as we expect them to be, a better filtration
of emissions would be called for, or a better enforcement
of regulations," said senior researcher James Quinn, a
molecular ecologist also at McMaster University.
The discovery is backed by nearly 10 years of similar
research of Quinn and his team in herring gull flocks
nesting around the Great Lakes.
knew that birds living near steel mills had elevated rates
of DNA mutation compared to those at rural sites," Somers
said. "Furthermore, the closer that gull colonies were
to steel mills, the higher their DNA mutation rates."
Although Quinn and colleagues had suspected smoke from
the mills was responsible, air pollution was hard to nail
down as the key culprit. Other factors could not be eliminated,
such as contaminated water or disease.
To isolate and analyze the effect of air pollution, Somers,
Quinn and others housed lab mice in cages exposed to open
air for 10 weeks from September to November 1999. One
shed containing 40 mice was placed one kilometer downwind
of two steel mills in Hamilton Harbor on Lake Ontario,
with another group of mice placed in a rural area about
30 kilometers away. All were kept warm with electric heaters.
In a report published in the Dec. 9 online version of
the Proceedings of the National Academy of Sciences, the
investigators found mice nearer the mills had offspring
with roughly twice as many genetic mutations as the rural
mice. The mice near the mills also had slightly smaller
litters -- roughly six as opposed to about eight -- although
these offspring were not any smaller than normal.
study is very important and forms the basis for more of
its type, because it shows the actual exposure animals
and humans receive in a real world, natural situation,"
said molecular biologist Bradley White of Trent University
in Peterborough, Ont. "Most studies are laboratory based."
Areas of DNA were analyzed that are predisposed to high
mutation rates and do not directly affect the health and
development of offspring. Although that might be a point
of criticism, Somers said, he noted previous studies involving
hazardous radiation have provided strong evidence that
mutation rates are related in both active and inactive
regions of the genetic map.
Somers explained studying DNA that is unusually sensitive
to mutation is the same as bringing a canary into a coal
mine is to spot deadly gas.
don't the canary and the miners to die at similar exposure
levels, otherwise the warning system is of little value,"
he explained. "We want to detect mutations that are of
no direct consequence early, in order to prevent those
of the more dangerous type later."
The researchers are trying to determine which air pollution
components cause this mutation effect. The main ingredients
of the smoke are chemicals called polycyclic aromatic
hydrocarbons, or PAH. They are byproducts of incomplete
fossil fuel combustion and prior studies in bacteria have
revealed they are highly mutagenic.
PAH concentrations were 50 times higher near the mill
than away from it, researchers found. The compounds usually
attach themselves to soot and tend not to travel far,
they said. Levels of PAH from car exhaust in urban environments
lie somewhere in between.
biggest obstacle is the lack of research funding," Somers
said. The projects he described were funded by a Canadian
federal program that was discontinued in 2002.