[Dermatologic risks of quartz-halogen lamps]

Halogene sources are used increasingly in general illumination. Their quartz envelop is technically necessary, but presents the disadvantage of to letting the emitted UVA, UVB and UVC go through. Originally used as in indirect lighting, they have been introduced as desk-top lamps, without filter. We have proceeded to the verification of their output with a spectrophotometer calibrated by actinometry and we have calculated their relative erythemal efficacy according to the Parrish's action spectrum for human erythema. We found that, at 10 cm from the human skin, the irradiance was able to induce a minimal erythema in about 10 minutes on clear back skin. At working distance (50 cm), a barely perceptible erythema could be observed on the back of the hands after 8 consecutive hours working. We also found that sunburn cells were present in the skin sensitized with a potent phototoxic agent (8-methoxypsoralen) applied 15 minutes before a 4-6 minutes irradiation with the halogen source (at 20 cm), thus, indicating a potential risk for local phototoxicity and photoallergy. The cumulative doses per year, for 4 hours exposure per day, five days a week, reaches 125 minimal erythemal doses, equivalent to the average yearly exposure of individuals for work and leisure. If one assumes that this regimen is maintained for 30 years, the risk for induction of skin cancers on the dorsal aspect of the hands and the forearms, may be increased by a 3.4 factor, according to the widely accepted previsional models.(ABSTRACT TRUNCATED AT 250 WORDS)