[Determination of the minimal erythema dosage and natural photoprotection of the skin in the population].

Effects of ultraviolet radiation (UV) on the human skin are summarized in the introductory part from physical and biological point of view, especially photoaging and photocarcinogenesis. Special attention has been paid to skin phototype which characterizes the individual susceptibility to UV. The minimal erythema dose (MED) serves for establishment of this susceptibility. The mean MEDs for white population in other countries are also shown here. Mechanisms of natural photoprotection in connection with instructions how to increase artificial photoprotection are described here. The investigation of skin type incidence in our population and determining their mean MEDs for UV-B and polychromatic light was the aim of practical work. The UV-B MED is in average 23.4 mJ/cm2. The further work has been concentrated on the assessment of pigmentation response after irradiation and especially on the comparison of the minimal erythema doses before season and after it. We found mean double increase of the MED after sunlight exposition during summer season. We suggested, that double increasing of seasonal natural photoprotection does not represent definitive protection for most people and does not impair summer warning system in media which is based on winter MEDs. Some recommendations for improvement of protection of Czech population against UV radiation are proposed in conclusion.