WASHINGTON: 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 on 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.