More than 10 years ago, Jim Quinn, a behavioral ecologist at McMaster University in Hamilton, Ontario, determined that herring gulls nesting near steel mills around the Great Lakes displayed higher heritable mutation rates than their rural cousins. In May Quinn and one of his students, Chris Somers, were finally able to pin the blame on airborne particles just a few micrometers in diameter.
They found that offspring born from male mice exposed to industrial air pollution showed twice the mutation rate of those whose fathers breathed rural or filtered polluted air. The most likely cause, Quinn says, are small particles that can carry known mutation-causing compounds, such as polycyclic aromatic hydrocarbons, deep into the lungs. Because particulates as well as polycyclic hydrocarbons are found in cigarette smoke, it’s likely that smoking could cause similar mutations.
The changes that Quinn saw showed up in genomic segments once known as junk DNA because they do not appear to code for necessary life functions. However, many of these regions are believed to play a role in diseases such as type 1 diabetes and Huntington’s disease. A separate study that examined 18 years of data on the prevalence of neurological diseases worldwide concluded that environmental factors may also contribute to disorders like Parkinson’s disease.
Quinn is now looking more closely at the link between air pollution and mutations handed down from females. Because males continually produce fresh sperm, the apparent mutagenic effect of air pollution starts to disappear when they begin breathing clean air again. But in females, eggs are produced while an individual is still a fetus, raising the possibility that exposure to airborne pollutants in utero could cause lasting damage. “There are many reasons other than mutations to be concerned about air pollution,” Quinn says. “This just adds strength to the argument that we need to do something about it.”