Evidence for a new paradigm for ultraviolet exposure: a universal schedule that is skin phototype independent.

Background: The Food and Drug Administration has published guidelines for manufacturer-recommended exposure schedules for ultraviolet (UV) tanning, intended to limit acute and delayed damage from UV exposure. These guidelines recommend that exposure schedules be adjusted for skin phototype. However, it has been shown that the dose necessary to produce tanning is similar for phototypes 2-4.

Methods: We observed tanning in phototypes 2 and 3 from repeated UV exposures over a 5-week period. Pigmentation was evaluated visually, instrumentally, and through Fontana-Masson staining of biopsies.

Results: The resultant pigmentation was equal or greater in phototype 3 compared with phototype 2 - both visually and instrumentally - measured on day 31 of the exposure protocol. The amount of melanin measured in biopsies taken 24 h postexposure was also greater in phototype 3 compared with phototype 2.

Conclusion: Published data on tanning in phototypes 4 and 5 support our findings that higher phototypes can develop pigmentation more efficiently than lower phototypes. Therefore, a universal exposure schedule (based on sensitivity of phototype 2) can be used for all phototypes that are expected to engage in indoor tanning. This approach will result in a reduction of the UV burden for skin phototypes 3 and above.