Biophysical and physiological effects of solar radiation on human skin by paolo u giacomoni // ‘‘Its not the substance, it’s the dose which makes something poisonous!’’When Paracelsius, a German physician of the fourteenth century made thisstatement, he probably did not think about light as one of the most obviousenvironmental factors. But his statement applies as well to light. While weneed light, for example, for vitamin D production too much light might causeskin ...