SIMULATED STRATOSPHERIC OZONE DEPLETION AND INCREASED ULTRAVIOLET-RADIATION - EFFECTS ON PHOTOCARCINOGENESIS IN HAIRLESS MICE

  • 1 January 1982
    • journal article
    • research article
    • Vol. 42  (7) , 2796-2803
Abstract
Solar UV radiation at the surface of the earth is a recognized cause of skin cancer. Postulated anthropogenic reductions in the thickness of the ozone layer would lead to an increased amount of UV radiation and hence would be expected to increase the risk of skin carcinogenesis. This study uses hairless (Skh:HR) mice as an animal model to study this increased risk. The mice were exposed 5 days per week to graded doses of UV radiation from a xenon arc lamp attenuated by 5 different thicknesses of Schott glass filters (WG320) to simulate various ozone layer thicknesses. A Robertson-Berger sunburning UV meter was used as one of the forms of dosimetry. The results of the various exposure treatments are expressed as the percentage of animals with tumors (incidence) vs. time after commencing irradiation and as cumulative tumor yield (average number of tumors per survivor) vs. time. With any given filter, the time to 50% incidence is inversely related to daily dose in Robertson-Berger meter units. The time to 50% incidence for comparable Robertson-Berger meter doses through different filter thicknesses increases with increasing thickness. The effective dose for skin cancer induction may be estimated from the Robertson-Berger meter dose, but the Roberston-Berger meter response spectrum underestimates the photocarcinogenic effectiveness of the shorter wavelengths. The cumulative tumor yield data are also consistent with these conclusions. Alternate weighting of the source spectra with the acute-response action spectrum for mouse skin edema gave a better correlation between unit dose and time to a tumor response, independent of the source spectral distribution. The mouse skin edema action spectrum, indistinguishable from a human skin erythema action spectrum for .lambda. > 295 nm, is similar in shape to the mouse skin photocarcinogenesis action spectrum for .lambda. > 295 nm.

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