Does exposure of human skin in situ to 385 or 405 nm UV induce pyrimidine dimers in DNA?

A previous report [Freeman et al.(1986) Photochem. Photobiol. 43S, 93S] indicated irradiation of human skin in situ with 385 or 405 nm radiation produced detectable levels of pyrimidine dimers in DNA. Since these wavelengths are absorbed poorly by DNA, these results suggested that DNA damage was sensitized by other absorbing molecules present in skin. Examination of two experimental aspects of the previous work indicated that (1) the static gel electrophoresis method for DNA dispersion used in lesion determination gave accurate values of levels of induced dimers, and (2) DNA damage apparently induced by 385 nm was actually induced by shorter wavelength UV present in the 20 nm bandpass beam of the monochromator. Current results indicate monochromatic 385 and 405 nm radiation are ineffective in dimer production in human skin in situ. (author)