An Action Spectrum for Uv Photocarcinogenesis *

Abstract

Abstract— Hairless mice were irradiated repeatedly by exposure to unfiltered black‐light (FR74T12 PUVA) fluorescent lamps and the time to development of skin tumors was determined. For several groups of animals the treatment variable was the size of the weekly dose. A similar approach had been used previously to determine dose‐response characteristics for other ultraviolet radiation emitting sources: a xenon arc solar simulator (with a series of five cut‐off filters producing five source spectra), and a fluorescent (FS40T12) “sunlamp”. The median tumor latent period (time period for just more than one half of the animals to develop at least one tumor each) was accurately predicted for all these ultraviolet radiation emitting sources by a mathematical equation incorporating the spectral source description and a spectral weighting function. The weighting function judged most appropriate for ultraviolet radiation‐induced photocarcinogenesis was the action spectrum, determined previously, for acute (single dose) skin edema in hairless mice. The mathematical equation assigns no effectiveness to wavelengths greater than 330 nm. There was no evidence for wavelength interaction in the spectral range of 26MW nm. Our data, combined with results of others, lead us to conclude that radiation with wavelength greater than 330 nm has an average relative efficacy (297 nm =1.0) less than 0.0002, and that this efficacy is not detectable with sources in which at least 2% of the UV radiation is in the UV‐B range.

Stimulatory effect of voluntary exercise or fat removal (partial lipectomy) on apoptosis in the skin of UVB light-irradiated mice

“…carcinogenesis ͉ sunburn ͉ cancer prevention ͉ sun-induced skin cancer N onmelanoma skin cancer is the most prevalent cancer in the United States (Ͼ1.0 million cases per year) (1)(2)(3), and ultraviolet B light (UVB) in sunlight is a major cause of these cancers (4,5). Although most skin cancers are squamous cell carcinomas and basal cell carcinomas that are easily cured if detected early, many people still die from these cancers, as well as from the more dangerous sunlight-induced melanomas.…”

Site and strand specificity of UVB mutagenesis in the SUP4-o gene of yeast.

“…Exposure to sunlight has been linked with the development of human skin cancer and experimental evidence indicates that among the wavelengths that penetrate the ozone layer, those responsible for carcinogenesis are within the UVB (280-320 nm) region ofthe solar spectrum (1)(2)(3). Although the precise mechanism is unknown, DNA damage, as expressed by genetic mutation, is very likely to be involved in the induction of cancer by sunlight.…”

Trends in Atmospheric Ozone and Ultraviolet Radiation: Mechanisms and Observations for the Northern Hemisphere

“…The action spectrum defines the wavelength dependent sensitivity of an organism to radiation damage of a specified type (Caldwell et al, 1986). The results discussed below adopt the MEE48 action spectrum which describes UV -induced carcinogenesis in mice (Cole et al, 1986). With the biologically effective irradiance defined by this action spectrum, a 1% decrease in column ozone leads to a 1.6-1.8% increase in surface irradiance, the exact value depending on the solar elevation.…”