for National Geographic News
So says a new study that tracked DNA damage in 63 steel-foundry workers in Brescia, Italy, who, under their normal factory conditions, were exposed to particulate matter.
The same damage may occur in city dwellers exposed to normal air, the researchers say.
Particulate matter includes suspended, tiny bits of dust, metal, or soot in the air, which can lodge deep in the lungs. Exposure to the substance has been linked to respiratory diseases, lung cancer, and heart problems.
Scientists know little about how inhaling particulate matter can cause health problems, according to lead study author Andrea Baccarelli of the University of Milan.
But they did find that exposed workers' DNA was damaged by a slowed rate of "methylation," a biological process in which genes are organized into different chemical groups.
Fewer groups means that fewer genes are expressed—or made into proteins—a crucial process in the body's regular maintenance.
(Learn how DNA works.)
Reduced-size gene groups like the ones observed in the new study have also been found in the blood DNA of lung cancer patients.
In the study, the workers' blood was sampled on the morning of the first day of their workweeks—before they were heavily exposed to the foundry's air—and again a few days later.
Comparisons between the two samples revealed significant changes in the methylation of four genes that may suppress tumors, said Baccarelli, who presented his research May 17 at the International Conference of the American Thoracic Society in San Diego, California.
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