Low-intensity sun exposure can harm skin DNA

Skin can sustain DNA damage during lower-intensity sunlight, even without turning pink, an Australian study found. The research included 58 people whose skin tones ranged from light to olive. Scientists applied naturally occurring ultraviolet levels to small areas on participants’ backs over several days, comparing gentler mid-morning exposure with stronger lunchtime conditions.

Biopsies showed cellular harm whether a comparable amount of UV arrived gradually or more quickly. Researchers found UV-related DNA lesions and changes in p53, a protein associated with cellular stress and damaged genetic material. The exposures were below the level needed to produce visible redness. Small episodes can build across months and years, potentially causing mutations that begin skin cancer, according to the researchers.

The findings question the idea that mornings and late afternoons carry little risk simply because sunlight feels less intense. Sun exposure still supports vitamin D and health, so the researchers are not recommending complete avoidance. They instead support guidance based on biological effects, including everyday sunscreen use for brief or unplanned time outside. Existing Australian precautions begin at a UV reading of 3. The paper appears in Photochemistry and Photobiology.