Predicted increased risk of squamous cell carcinoma induction associated with sunbed exposure habits

Summary Background Solar ultraviolet radiation (UVR) is recognized as the principal environmental cause of skin cancer. In particular, the risk of induction of squamous cell carcinoma (SCC) has been shown to increase with cumulative exposure to UVR. Models of risk of SCC induction have been developed but these do not include the use of sunbeds. Objectives To explore the links between sunbed exposure and risk of SCC induction. Methods To this end, the values of published on‐site UVR levels emitted from sunbeds were used to provide real measured sunbed exposure levels to inform the model. The model incorporated three conditions of exposure: day‐to‐day, holiday and sunbed exposure. The risks associated with different exposure scenarios were implemented in the model. Baseline exposure comprised day‐to‐day and holiday exposure. Relative risk (RR) was defined as the risk of SCC induction from (sunbed + baseline dose)/baseline dose. Results The RR of SCC induction from estimated median sunbed exposure output [176 standard erythemal dose (SED) per year; 20–35 years of age] in addition to median baseline sun exposure level (166 SED year + 85·5 SED per year holiday) was 1·9 (90% risk increase) up to 55 years of age. A higher sunbed exposure (302 SED per year; 20–35 years of age) produced an RR value of 2·8 (180% increase) at 55 years of age. Conclusions This is the first time that a risk model for SCC of the skin has been developed that includes estimated sunbed doses derived from measured irradiance data. The model demonstrates that the additional risk associated with sunbed use may be significant, particularly when high‐output, fast‐tan sunbeds are used. What's already known about this topic? Cumulative exposure to solar ultraviolet radiation (UVR) is a risk factor in the induction of squamous cell carcinoma (SCC). High‐output sunbeds emit significant levels of UVB radiation. Sunbeds in the U.K. emit UVR levels that exceed the European limits. What does this study add? This study uses published emission spectra from sunbeds to quantify the increased risk of SCC induction according to pattern of use and background sunlight exposure. By age 55 years, the risk of SCC induction from exposure to median UVR levels between the ages of 20 and 35 years from a sunbed is increased by 90%. A predictive, quantifiable relation is proposed between sunbed use, including the type of sunbed used, and SCC induction.