Using skin bi‐fold thickness changes for assessment of <scp>SKH</scp>‐1 mice exposed to <scp>UVC</scp> radiation

The SKH-1 mouse model is commonly used to assess the effects of ultraviolet light exposure on skin using visual and biological endpoints. Although skin bi-fold thickness is a well-established quantitative measure of edema, evidence characterizing its use to evaluate skin responses in the UVC range remains limited. This study evaluated skin bi-fold thickness measurements made using a digital caliper. Hairless SKH-1 mice were exposed using the narrow bandwidth output from a monochromator with wavelengths from 200 to 270 nm. Post-exposure thickness measurements were normalized against pre-exposure thickness measurements to determine the fold change. These findings were compared with qualitative visual assessments of changes to the skin. The results indicate that quantitative measures of increases in skin thickness are correlated with subjective visual scoring measures. The observed magnitude of the bi-fold change following UVC exposures was limited in this study because exposures were at doses close to the threshold dose for causing a visually observed change to the skin. The results support using skin bi-fold measurements for quantifying skin responses to ultraviolet light exposure.