SYDNEY, July 1 (Xinhua) -- An Australian study has found that even short periods of sun exposure during hours of low sunlight traditionally considered "safe" can cause skin damage and contribute to skin cancer risk.
The findings challenged long-held public health assumptions that time outdoors early or later in the day doesn't cause skin harm, according to a statement from Australia's QIMR Berghofer Medical Research Institute released on Wednesday.
"You can get the same dose of UV [Ultraviolet] radiation in a short time in the middle of the day or a longer time earlier or later in the day. Our research has shown it is the total dose that is important -- it doesn't matter how long it takes to get it," said QIMR Berghofer Professor Rachel Neale.
"People potentially get lulled into a sense of security when the intensity of sunlight is weak, and they spend too long outdoors without adequate protection. We have shown that it is a problem for skin damage," said Neale, co-lead of the study published in Photochemistry and Photobiology.
Biopsies revealed DNA damage and cellular stress responses regardless of whether the UV exposure occurred quickly or more slowly, according to the study.
Researchers measured biomarkers, including p53, a protein linked to DNA damage, and found evidence of harm at levels below those that trigger skin redness.
The study's co-lead, Professor David Whiteman at QIMR Berghofer, said repeated low-level exposure could "have a cumulative impact on the skin and can lead to mutations that will initiate skin cancer."
The researchers emphasized that sunlight remains essential for vitamin D and overall health, but said sun protection should be used more consistently, even during brief or low-intensity exposure. ■