Tanning bed technology circa the year 2000, when the industry began using lamps that emit larger doses of long-wave ultraviolet A (between 335 and 400 nm), is no safer than tanning beds pre-2000, a meta-analysis of the association between melanoma and tanning beds has shown.
Globally, people who had been exposed to tanning beds were 16% more likely to have melanoma; in the United States, where tanning bed intensity is unrestricted, the risk from exposure is 23% higher than in the general population. In Europe and in Australia and New Zealand, where the intensity is limited to an ultraviolet index of 12 and 36 respectively, the increased risk was not significant, reported investigators in the March issue of the Journal of the American Academy of Dermatology (doi:10.1016/j.jaad.2013.11.050).
Further, tanning bed use before the age of 25 years additionally increased a person’s melanoma odds to 35% compared with 11% in those who had indoor tanning exposure after the age of 25 years. Sophia Colantonia of the University of Ottawa and her coauthors also found a threshold effect of 10 or more tanning bed sessions being associated with the highest risk of melanoma.
"Assessing and communicating health risk to patients in an easily understood metric based on number of tanning bed sessions could be helpful to clinical practice," wrote the investigators.
For the meta-analysis, the investigators searched Scopus, MEDLINE, and the Cumulative Index to Nursing and Allied Health Literature for studies published before Aug. 14, 2013. In all, 31 studies that included 14,956 cases of melanoma and 233,106 controls were analyzed. In those who had ever used a tanning bed, the odds ratio (OR) for melanoma was 1.16 (95% CI, 1.05-1.28). Tanning bed use after 2000 had an OR of 1.22 (95% CI, 1.03-1.45). For individuals who had used 10 or more tanning bed sessions, the OR was 1.34 (95% CI, 1.05-1.71). North Americans were found to have higher rates of melanoma (OR, 1.23; 95% CI, 1.03-1.47) vs. Europeans and Oceanianians for whom the OR was not significant. Ten or more tanning sessions in a lifetime was associated with the highest risk of melanoma (OR, 1.34; 95% CI, 1.05-1.71).
Limitations to the meta-analysis included that not all of the studies used the same age range for their study groups, and evidence quality ranged from mediocre to poor, the investigators noted.
The investigators reported that there were no funding sources, and no conflicts of interest were declared.