Everyone knows that second-hand smoke is bad for the lungs, but a new study shows that it can also cause mutations in men's sperm, which they can then pass on to their children, reports the Guardian's Alok Jha. Although previous research has shown that men who smoke are at higher risk of developing "abnormalities in their sperm," and that paternal smoking can lead to a higher risk of childhood cancer for their kids, Jha says, the new study, published in PNAS, also suggests that secondhand smoke can do the same damage. The researchers exposed 32 mice to the total amount of smoke generated by three to 16 cigarettes for up to 90 minutes a day for two weeks. When they examined the animals' sperm six weeks later, the researchers found that mice in the group that simulated direct smoking had an average mutation rate of 4 percent to 4.7 percent, compared to the non-smoking mice that had a mutation rate of about 1.3 percent to 1.5 percent. The mice that simulated passive smoking showed an average mutation rate in their sperm of 2.6 percent and 4.6 percent for low and high doses of smoke, respectively, Jha adds. Lead author Francesco Marchetti tells Jha that these findings provide "compelling evidence in support of the argument that passive smoking should be regarded as a germ cell mutagen in humans."
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