Neoplastic transformation of neonatal human fibroblasts exposed in vitro to radiation from a quartz-halogen lamp.

The use of unfiltered quartz-halogen lamps exposes human skin to radiation that spans much of the ultraviolet (UV) spectrum. Reports indicate that exposure to quartz-halogen lamps is erythemogenic, mutagenic, and carcinogenic. To compare the carcinogenic potential of quartz-halogen lamps with that of other UV sources, we determined the dose dependence for cytotoxicity and neoplastic transformation in neonatal human fibroblasts exposed in vitro to: a 15 W germicidal lamp (primarily 254 nm radiation), a 15 W Cool White fluorescent lamp, and an unfiltered 20 W quartz-halogen lamp. Fluence-survival relationships were multiphasic with linear dose response below about 40% survival, and all three sources produced fluence-dependent transformation as indicated by induction of anchorage-independent growth. Maximum transformation frequencies were observed at fluences of 5-8 J/m2 for the germicidal lamp, 6.3 kJ/m2 for the fluorescent lamp, and 300 J/m2 for the quartz-halogen lamp. These data confirm the carcinogenic potential of the quartz-halogen lamp.