Discussing your toenails may not be an intriguing conversation starter, but as it turns out, they say a lot about your current health status. Recently, a study conducted by researchers at UC San Diego and Harvard found that toenails harbor nicotine levels that could indicate your lung cancer and heart disease risk, even if you aren’t a smoker.
Let’s say you’re sitting in a club or restaurant next to friends who are smoking. The smoke being exhaled or exiting the end of a lit cigarette and circulating in the room contains scores of chemicals that get stored as biomarkers in your nails, hair and skin. Even though you aren’t a smoker yourself, as you breathe in the smoke-filled air you are passively smoking. This is also known as secondhand smoke.
Wael K. Al-Delaimy, MD, PhD, chief of the global health division at UC San Diego, a member of the Cancer Center, and co-investigator of this study was looking for a way to measure passive smoke exposure. At first he was measuring nicotine exposure in hair when he learned his Harvard co-author had a very large collection of toenail clippings.
Since hair and toenails are formed from the same kind of tissue, Al-Delaimy decided to take advantage of the collection for this study. According to Al-Delaimy, there are clear advantages to studying toenails.
"They can be stored at room temperature for years and because they grow slowly—only about 1 centimeter every nine to 12 months— toenails give a true nicotine exposure during the past year.”
While the current study analyzed toenail clippings of men--210 with lung cancer and 630 without lung cancer for a comparison--Al-Delaimy has also shown that toenail nicotine levels accurately predict the risk of heart disease in women. In a previous study, women with the highest nail nicotine levels were shown to have a 42 percent higher risk of heart disease compared to those women with the lowest level.
Heart disease is the leading cause of death in the United States for men and women of all ages; Lung cancer is the leading cause of cancer-related death in the United States for men and women, according to the Centers for Disease Control.