A type of ultraviolet light in sunlight, which is also present in light emitted in tanning booths, damages and promotes premature aging of the skin with repeated daily exposure, according to a new study.
Researchers from the University of Michigan Medical School found that exposing skin to ultraviolet A1 (UVA1) light led to the creation of a molecule called matrix metalloproteinase 1 by skin cells. This molecule breaks down the protein collagen, which keeps skin firm and youthful.
The findings about UVA1 light, which are published in JAMA Dermatology, are important because much research on ultraviolet light's effects on skin focus on ultraviolet B rays, since those cause sunburn. "But there is very little UVB in sunlight, and most UVB exposure is at midday. During the rest of the day it's mostly UVA, with UVA1 being the majority," study researcher Dr. Frank Wang, M.D., a medical dermatologist and assistant professor of dermatology at the university, explained in a statement.
"UVA1 is also the main component of tanning booth light. So, we wanted to look at whether it can predispose skin to premature aging by simulating repetitive daily exposure," he added. "We found that it can. Furthermore, the mild tanning that occurs does not seem to protect against damage from additional exposures."
The study included 22 healthy volunteers, who underwent repeat exposure by UVA1 light to a patch of skin on their buttocks (the equivalent of two hours of sun exposure). Researchers found that the more their skin was exposed to the light, the higher the pattern of production of metalloproteinase 1.
The finding suggest sunscreens need to contain more UVA1 blocking chemicals, as right now, the Food and Drug Administration has only approved zinc oxide and avobenzone as sunscreen ingredients that can block this kind of light.