[Ultraviolet rays and their biological effects]

Abstract

In conjunction with contamination of the atmosphere by freons interest in geophysical and health aspects of "ozone holes"--seasonal incidence of increased intensity of UV radiation--is increasing. Its biological effects depend on the intensity, period of exposure and wavelength. There is a wide range of different damage, local as well as general. In addition to pigmentation of the skin and symptoms produced by an elevated histamine blood level we find also changes which may have more serious and permanent consequences. These changes include the number and structure of Langerhans islets, changes of the peripheral capillary walls, dimerization of pyrimidine and thymine in DNA. These changes contribute to the development of malignancies of the skin. After exposure of the eye changes of pigmentation are found, and depending on the dose, also development of conjunctivitis or retinal damage. Recently interaction of UV radiation with arsenic was investigated. Conversely therapeutic effects of UV radiation in combination with chemotherapy are used in dermatology, such as inhibition of contact sensitization.