Inherited Mutations Linked to Air Pollution
Male Mice Breathing Pollution Particles Father Mutant Offspring
May 13, 2004 -- Air pollution is bad for your health -- and may affect the health of future generations, mouse studies suggest.
While genetic effects on humans have yet to be proved, the findings sound like a real-life X-Men episode.
James S. Quinn, PhD, and colleagues previously found that sea gulls near steel mills had higher rates of DNA mutations than gulls in rural areas. They now show that offspring from normal mice housed near steel factories and a busy highway had higher DNA mutation rates than offspring from normal mice housed in a rural area.
What's going on? To find out, Quinn's team installed high-efficiency air filters in the mouse house. When the filters pulled particulate emissions out of the air, the mutation rate dropped in the offspring. The conclusion: Either the particles themselves or something they carry leads to DNA mutations. The findings appear in the May 14 issue of Science.
The probable culprits are compounds called PAHs. Some of these compounds cause genetic changes in humans as well as in mice.
Here's the scenario. Tiny PAH-bearing particles fly out of steel-mill smokestacks and car exhaust pipes. They float in the air and are breathed deep into the lungs. From the lungs, the PAHs enter the blood stream. They move throughout the body, eventually finding their way to the reproductive organs. There they cause mutations in the cells from which sperm arise. Finally, a mutant sperm fertilizes an egg -- causing mutations in the next generation.
Of course, mutant offspring is only the latest health problem from air pollution. Dirty air also causes heart disease, lung disease, lung cancer, and developmental damage.
"To reduce the potential risk of harmful [in]heritable mutations for humans and wildlife, along with a suite of other health problems, we suggest that steps be taken to reduce levels of airborne particulate matter in urban environments," the researchers conclude.
An editorial by Johns Hopkins researcher Jonathan M. Samet, MD, and colleagues accompanies the Quinn team's report. They note that while U.S. air pollution has dropped over the past few decades, current levels of air pollution are enough to affect people's health.
The current findings, they conclude, "would extend the adverse health effects of air pollution beyond effects on [body] cells in the exposed generation to germ cells -- with the attendant implications for health risks to future generations."