Toxins in the environment may accelerate aging, study finds

Avoiding environmental toxins may be the key to preserving your youth, according to new research.

Just as exposure to carcinogens increases a person’s risk for cancer, experts now believe a class of environmental toxins – known as gerontogens – may put people at an increased risk for accelerated aging. Toxins present in cigarette smoke, UV rays and chemotherapy are all suspected gerontogens - capable of accelerating the rate at which a person ages.

“Genetic studies have taught us only 30 percent of aging is genetic, meaning the other 70 percent comes from the environment,” study author Dr. Norman Sharpless, director of the Lineberger Comprehensive Cancer Center at the University of North Carolina, told

Now, in a new study published in Trends in Molecular Medicine, researchers have developed a simple test to help pinpoint exactly which toxins might be worth avoiding to stave off some of the effects of premature aging.

Aging occurs when the body undergoes a biological process known as senescence, when healthy cells become damaged and lose their ability to divide. Over time, these damaged cells accumulate in the body, consuming resources and unleashing hormones with inflammatory properties.

“Having a few [of these cells] is not a big deal,” Sharpless said. “But over the course of a lifetime, as they accumulate, they [contribute to] aging and many of the diseases we associate with aging.”

In their study, Sharpless and his colleagues developed a system that allowed them to expose mice to certain gerontogens and then measure the accumulation of senescence cells in their bodies. Each group of mice was exposed to a different environmental factor: Some were made obese, while others were exposed to cigarette smoke, UV light and arsenic.

According to their results, both cigarette smoke and UV light were strongly associated with accelerated aging, while obesity and arsenic exposure did not appear to have a significant impact on senescence.

“Our work reasonably says cigarette smoking is the thing we could really do something about that would benefit the aging biology of a large number of people,” Sharpless said. “But we’re also reasonably certain there are other gerontogens we don’t know about yet.”

The researchers hope that other labs will use their experimental models to test how other toxins might impact the aging process.

Previous testing in humans has also indicated that breast cancer patients exposed to chemotherapy experience accelerated aging. These results were based on a blood test measuring levels of P16, a gene which experiences an exponential increase in its expression as we age. P16 is also one of the markers by which senescence is measured.

“Chemo for breast cancer increases molecular age by about 15 years equivalent of chronologic aging; that’s a lot,” Sharpless said. “But it’s not surprising to oncologists. We’ve known for a long time there is long-term toxicity with these drugs.”

Sharpless and his colleagues hope that tests offering a better measure of a person’s “physiologic” age might help doctors develop more appropriate treatment methods for different kinds of patients.

“There are a lot of situations in medicine where we decide to do something based on age. If you are 60 and have breast cancer, we might give highly toxic chemotherapy, whereas if you are 80 we will give you more gentle chemotherapy,” Sharpless said. “But every physician knows that is problematic; there are 60-year-olds who are physiologically 80 and 80-year-olds who are physiologically 60…If one had a better marker of physiologic age, you could strategize better.”