Cancer of the melanocytic system

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:198693

Setlow, R B

Within reasonably homogenous populations, skin cancer increases toward low latitudes, but this association does not indicate the wavelength regions involved in cancer induction. At present, the only animal model suitable for determining the wavelengths effective in melanoma induction are certain inter- and intraspecies hybrids of the small fish, Xiphophorus. Genetic evidence indicates that the hybrids contain only one tumor suppressor gene and, therefore, are very sensitive to cancer induction by single exposures to light. 5-Day old fish were exposed in spectrophotometer cuvettes, to different monochromatic wavelengths and fluences. The fish were kept for two months in tanks shielded with yellow plastic, so as to minimize the possibility of photoreactivation, and were scored at four months. The melanoma prevalence increased with exposure to a maximum of {approximately} 0.5. The fluence-response curves were fitted to surviving fraction = a+b(l-e{sup {minus}kE}), where a is the background prevalence with no exposure, b is the maximum induced prevalence, k is the sensitivity parameter (the cross section for melanoma induction), and E is the incident fluence. The value of k at 302 nm was 0.05 m{sup 2}/J giving a mean melanoma inducing exposure, for swimming fish, of 200 J/m{sup 2}, corresponding to 3.5 cyclobutane pyrimidine dimers per Mbp of DNA in irradiated fish skin.

• Research Organization: Brookhaven National Lab., Upton, NY (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 198693
• Report Number(s): BNL--62461; CONF-9405134--2; ON: DE96004162
• Country of Publication: United States
• Language: English

Related Subjects

56 BIOLOGY AND MEDICINE
APPLIED STUDIES
CARCINOGENESIS
EXPOSURE CHAMBERS
FISHES
MELANOMAS
ULTRAVIOLET RADIATION
ULTRAVIOLET SPECTROMETERS