Fig. 1.

Flowchart of study protocol. Following detailed assessment of skin type, skin lightness and UVR-erythemal sensitivity, 65 volunteers of phototype I-VI (n = 12, 14, 19, 6, 7, 7, respectively) each provided a baseline urine sample. Volunteers with the lightest (phototype I, n = 8) and darkest (phototype V/VI, n = 7) skin were exposed to a UVR dose personalised to their sunburn threshold i.e. 80% of their minimal erythema dose (MED), and the temporal change in 8-oxodG and 8-oxoGuo evaluated through collection of every pass of urine over a five day period post-exposure. One participant had a baseline 8-oxodG 22 SD higher than the mean of the cohort and 55 times higher than the mean of the post-UVR samples from the same individual; this outlier was removed from the analysis.