Article publication date
29 June 2026
ARPANSA review date
30 July 2026
Summary
This experimental study on human subjects examined if low doses of ultraviolet (UV) radiation produce adverse effects in skin. 58 pale-skin participants (Fitzpatrick type I-III) were exposed to UV radiation doses of 0.7 and 1.6 standard erythemal doses (SED) at 3 locations for each dose on their back. A biopsy of the exposed area was taken 15 minutes after exposure along with a biopsy of an unexposed control area. The remaining exposure sites were biopsied at 24 and 72 hours after the first exposure, with UV exposure repeating at 24 and 48 hours. Additionally, the participants were divided into two groups according to the rate at which the doses were applied, either at UV index 2.8 or UV index 8.0, to investigate whether the intensity at which a dose is applied has an impact.
UV exposure caused an increase in DNA damage at all time points, with the higher dose group exhibiting more DNA damage than the lower dose group. Tumour supressing gene expression was increased in the biopsy taken after 24 and 72 hours, but not at 15 minutes. The higher dose group again exhibited greater increases than the lower dose group. A small non-statistically significant increase in oxidative stress was measured for each dose group. The UV index used to apply the dose did not affect any of the endpoints measured.
Published in
Photochemistry and Photobiology
Link to article
ARPANSA summary
The study found that low doses of UV radiation cause DNA damage in humans and an increase in the amount of tumour-suppressing genes. This is because the amount of DNA damage was proportional to the UV dose, which is in agreement with other studies conducted in humans (Tewari, A. et al., 2012; Olsen, C. et al., 2017; Katiyar, S. et al., 2007). However, the short-term nature of the study means it was not designed to assess the long-term consequences of UV-induced DNA damage at low doses, including its potential effects on tumour development or growth.
The doses used in this study were chosen to reflect doses that have been estimated to maintain adequate vitamin D when exposed four times per week (Elliot, M. et al., 2023; Neale, R. et al., 2024). This is a challenging area of sun protection as consideration must be given to balancing the risks and benefits of sun exposure. The Australian Skin and Skin Cancer Research Centre has published a joint position statement on balancing these factors. However, many Australians are routinely exposed to UV doses that far exceed those used in this experiment (Australian Bureau of Statistics, 2024), a fact that is reflected in the very high incidence and mortality of skin cancer in Australians (De Pinto, G. et al., 2024).
This study showed that direct DNA damage happens even when a sunburn does not occur, underscoring the need to use all five sun protection measures whenever the UV index is over three: slip, slop, slap, seek and slide. In the context of this study where a UV index below three was used for some participants, it is important to note that DNA damage can happen at high or low UV index values, provided a person is exposed for a long enough time to accrue the same total UV dose. In relation to the above sun protection advice, this means that even when the UV index is below three, sun protection should be used if in the sun for a prolonged time period, as an unprotected person can accrue a substantial UV dose in those circumstances.
