Methods for exposure of laboratory animals to ultraviolet radiation

Two different sources of ultraviolet B (UVB) radiation, an electronically c ontrolled UVB exposure unit, containing FS40 tubes, and a hand-held Kromaye r lamp, were evaluated for actual irradiance in W/m(2) and spectra (physica l dosimetry and biological dosimetry (skin effects in rodents)). The techni cal studies of the FS40 sources demonstrated that the flux intensity of the lamps could be changed electronically, without affecting the spectrum. Thu s it was possible to standardize UVB exposure electronically. The biologically effective doses of these sources were analysed in RIV-Tox Wistar rats and BALB/c mice. After low doses of UVB radiation, histopatholo gical changes such as acanthosis, hyperkeratosis and dermal inflammation we re observed in the skin without the presence of major side effects such as erythema and oedema. After higher doses of UVB radiation erythema and oedem a were clearly visible. Quantitative studies showed that the minimal erythe ma dose, as a biological parameter, correlated well to the emission in J/m( 2). In addition, biological parameters such as acanthosis and inflammation in the skin correlated well to the actual exposure in J/m(2) and were sensi tive biomarkers for UVB-induced skin toxicity. Thus, in addition to minimal erythemal doses, acanthosis and inflammation may also be applied as biolog ically relevant doses for studies of the biological effects of UVB radiatio n.