Soot damage may pass through generations

Breathing soot from factories or roads 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 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 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.

There has 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.

The same researchers from Ontario’s McMaster University are reporting in the journal Science that they have 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% lower than the mice exposed to full-strength steel mill pollution.

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.