CHAPTER 13 



Sunburn 



Harold F. Blum^ 



National Cancer Institute'^ 



Bethesda, Maryland 



and 



Department of Biology, Princeton University 



Princeton, New Jersey 



"... I am black; because the sun has looked upon me." 



— Song of Solomon 



Erythema. Sitntan. Photosensitization. Protection against sunburn. Mechanisms. 

 Fact and fancy. References. 



Although sunburn must always have been an obvious nuisance to man, 

 it seems to have received little attention from scientists before the present 

 century. To be sure, the true nature of the phenomenon could not have 

 been understood until the discovery of ultraviolet radiation in 180P but it 

 was another half century before it was recognized that sunburn is caused 

 by this agent and not by heat.^'^ The first recorded statement I have 

 found that sunburn is caused by ultraviolet radiation is in an account by 

 Charcot which appeared in 1858. This describes two cases of burns from 

 electric arcs and cites similar experiences by the physicists Foucault and 

 Despretz. Foucault had found that uranium glass protected against the 

 burning, which was attributed to the ultraviolet or, as they were then 

 called, the " chemical " raj^s. Charcot clearly recognized that these burns 

 were comparable to sunburn. Widmark in 1889 and 1891 made a more 

 complete study, finding that the rays from a carbon arc passing through 



1 Present address: Department of Biologj% Princeton University. 



2 National Institutes of Health, Public Hejilth Service, Department of Health, 

 Education and Welfare. 



' In that year Ritter found that the sun's spectrum beyond the violet caused the 

 blackening of silver chloride (Ritter, 1803). One year earlier Herschel had shown the 

 existence of the infrared. 



* Actually, imconcentrated sunlight does not heat the skin enough to produce a 

 burn. For a discussion see Blum (1945). 



'" Historically interesting is a paper by John Davy (1828), who concluded that, in 

 order to elicit a burn, all wave lengths must affect the skin simultaneously. 



487 



