According to researchers at the University of Michigan Medical School, better sunscreens are needed in order to prevent the effects of aging. Even a low level of daily sun exposure can quickly lead to skin damage, they claim, causing the telltale signs of aging, such as wrinkling and sagging
In a new write-up that was released online on December 4, 2013 in the journal JAMA Dermatology, the study authors discuss how exposure to low levels of ultraviolet A1 rays, also known a UVA1, can begin to damage delicate skin tissue at the molecular level after only two days. UVA1 light makes up the majority of UV light which humans are exposed to throughout the day. It is also a part of the light given off by tanning beds.
The technique used by the research team to measure UVA1’s effects at the molecular level involved using advanced gene expression analysis of human skin samples.
To carry out their study, the researchers shined a low level of pure UVA1 light on a small area of the buttocks of 22 volunteers. The subjects used in the study were fair-skinned individuals and the amount of UVA1 exposure that they received was equivalent to about two hours of strong exposure to the sun. This was meant to mimic the same level of exposure that a person might get in their daily life. After a day, the researchers measured changes in pigmentation in the exposed area. They then took small skin samples in order to test which genes had been activated by the light exposure. This process was repeated three additional times for each person.
The team found that after only two exposures to UVA1 light, the skin cells began to create a substance called matrix metalloproteinase 1, or MMP1, which breaks down collagen. Collagen is what gives skin the firmness and smoothness associated with youth. When it breaks down, wrinkles begin to form. And, although the study participants’ skin did begin to tan, this tanning did not protect them from MMP1 production. In fact, the amount of MMP1 production increased with repeated UVA1 exposure.
Lead author Dr. Frank Wang notes that, although premature aging due to sun exposure has gotten quite a bit of attention in the past decade, most researchers have put their attention on UVB rays, which are responsible for causing sunburns. However, UVA1 is the primary type of UV light that people are exposed to throughout their day-to-day lives. It is also the main type of UV rays found in tanning booth light. For this reason, he and his team wanted to see what effects it could have on the skin.
Unfortunately, the study authors say, existing sunscreens provide very little protection against UVA1. The researchers say that their hope in revealing this information is that there will be better sunscreens developed as a result. In addition, they hope that people will be more cautious about their sun exposure. The bottom line, say the researchers, is that sunscreens need to be improved so that they are capable of blocking UVA1 rays. Zinc oxide and avobenzone are currently the only two FDA-approved ingredients which are able to block this type of light. Window glass and most clothing are not capable of blocking it.
They also note that using UVA1-blocking sunscreens throughout the day, rather than just at peak sunburn hours, is advisable. Where sunburn-creating UVB rays tend to be most intense during late morning and early afternoon, UVA1 exposure occurs anytime the sun is out.
While other types of UV rays have been linked in previous studies to skin cancer, the current study did not attempt to assess whether UVA1 could contribute to cancer risk. It only dealt with how these rays might affect premature aging and how better sunscreens might work to to prevent it.
By Nancy Schimelpfening