UV transmission measurements of small skin specimens with special quartz cuvettes

Background: The penetration of different wavelengths of UV radiation throug h human skin is of major importance, especially for the determination of ph otoprotective properties of sunscreens and UV-protective clothes. Objective : In this study we present a new method for the measurement of UV transmiss ion through small skin specimens. Methods: The transmission measurements we re performed by using a UV spectrophotometer with an integrating sphere ope rating in the wavelength range of 280-390 nm. For the skin samples, special quartz glass cuvettes were developed which allowed measurements for very t hin and small skin specimens. Furthermore, the cuvettes prevented dehydrati on of the specimens and guaranteed, by using an additional diaphragm, that the transmission data were derived solely from the small skin specimen exam ined. Specimens measuring 8 x 3 mm(2) with a thickness of 0.3 mm (histometr ic and sonographic control) were taken from the thighs of 10 subjects via s have biopsy. Results: in the UVA range (315-390 nm) we obtained a mean tran smission of 4.6% and for the UVB range (280-315 nm) of 0.9%, No significant (p > 0.14) difference of UV transmission was found between the individual skin specimens. Conclusion: This new method seems to be well suitable for U V transmission measurements of small skin specimens. As UVA radiation has a much deeper penetration depth and in in vivo situations dermal hemoglobin could have an effect on UV penetration, the present method is better suitab le for the investigation of UVB-induced biological adaptation mechanisms an d the impact of topical agents on UVB transmission of the epidermis. Copyri ght (C) 2000 S. Karger AG, Basel.