Okay, so you know that breathing polluted air is bad for your heart and, of course, your lungs. But did you know it might be bad for your swimmers, too?
In a study performed in an industrial Canadian city, scientists raised mice in a shed downwind of a highway and two steel mills. After just three weeks, the test mice's sperm was showing a greater level of genetic mutations that the control group, which breathed filtered air. By the end of the study,
DNA in the sperm of the mice in the polluted area contained 60% more mutations, had more strand breaks, and had more bases that had been chemically modified via the addition of a methyl group. That modification, called DNA methylation, can affect whether a gene is expressed.
The link between air pollution and reproductivity has been studied in humans, but most studies focus on the outcome of pregnancy rather than on the effect on male reproductive capacity. Studies of the effect of air pollution on human male gametes have generally been considered skewed by uncontrolled variables like lifestyle and diet, but this research makes a pretty clear case for more human studies. Anyone have any statistics on the change in rates of male fertility in the past hundred years?