RELATIONSHIP BETWEEN SKIN COLOR AND SUN EXPOSURE HISTORY - A STATISTICAL CLASSIFICATION APPROACH

In this study our aim was to determine the biophysical values of const itutive skin color in Caucasians and to define the correlation between skin color and phototype assessed according to the Fitzpatrick method . Constitutive skin color was measured on the buttock, with a Minolta CR-200 colorimeter, in a population of 557 consecutive subjects belong ing to phototype categories I, II, III and IV, The colorimeter express es the results in five different color systems, We used the ''Yxy'' an d La*b* systems, which are the most widespread in dermatology. Statis tical analysis of the data showed that the ''Yxy'' system is even more discriminant than the La*b* system when the Fitzpatrick classificati on scheme is adopted as the reference and shows a poor ability to corr ectly classify the intermediate phototypes (II and III), On the contra ry the ''Yxy'' system performs well in distinguishing phototypes I and IV, To establish whether this low discriminating capacity for phototy pes II and III is related to a low discriminating capacity of the meth od suggested by Fitzpatrick or by our procedure, an objective techniqu e (minimal erythemal dose) should be used to evaluate the percentage e rrors of classification of both the Fitzpatrick method and instrumenta l measurement of skin color, The results of such a study are extremely important because the evaluation of skin color is objective, simple a nd has potential applications in dermatology and cosmetology.