The ultraviolet C energy emitted from FS lamps contributes significantly to the induction of human erythema and murine ear edema.

FS ultraviolet (UV) lamps are used extensively to study the biological effects of ultraviolet radiation. Using published data, we investigated the relative contributions of the UVC (250-289 nm), UVB (290-319 nm), and UVA (320-400 nm) portions of the FS lamp emission spectrum to the induction of human erythema and murine ear edema. Many investigators contend that the biological activity of the spectrum emitted from these lamps resides primarily in the UVB region, based on the proportions of the power emission spectrum in this region (53.6%) versus the small relative contribution of UVC (3.2%) and the low biological activity of UVA (43.2%). However, if the biological effectiveness spectrum of FS lamps is calculated by multiplying the power spectrum with different action spectra, the biological effects of UVC are readily observed. For example, 10.4% of the murine ear edema activity and 11.1% (Parrish) or 16.7% (McKinlay-Diffey) of the human erythemal activity is due to the energy emitted in the UVC region. Experimental determination of human erythema and murine ear edema demonstrated that, for an equal amount of energy delivered, radiation from the unfiltered lamps was more potent in causing these responses than radiation from filtered lamps, and the ratio of effectiveness could be predicted by the effectiveness spectra. Thus, the contribution of UVC emitted from FS lamps to biological effectiveness spectra should not be ignored.(ABSTRACT TRUNCATED AT 250 WORDS)