Measurements of sun sensitivity in five European countries confirm the relative nature of Fitzpatrick skin phototype scale.

Abstract

Skin colour and sun sensitivity are highly related to the distance to the equator: people in southern latitudes are usually darker and less sensitive to sun than in northern latitudes. Whether differences in sun sensitivity can be found in a relatively homogenous European population is unclear. We aimed to objectively measure sun sensitivity (assessed as pigment protection factor (PPF)) in five European countries, relate it to self-assessed Fitzpatrick skin phototype (FST) and to determine whether PPF levels in the different FST categories are dependent on the investigated countries. Volunteers (n=569) were recruited in Copenhagen (Denmark), Dublin (Ireland), London (England), Münster (Germany) and Ioannina (Greece). Skin phototype was self-assessed using the FST scale. PPF was measured at both sun-protected buttocks and five sun-exposed skin sites by a skin reflectance spectrophotometer. Overall, there were statistically significant differences in PPF of the buttocks, inner arm, outer arm, forehead, chest and back between the five countries (P≤.031). Generally, PPF level was lower in northern than in southern latitudes. PPF of the buttocks was similar in all countries for those who identified as FST I (P=.723). However, it was statistically significantly different (P≤2.913*10-4 ) and country-dependent for those who identified as FST II-IV. Objectively measured sun sensitivity is higher (lower PPF) in northern compared with southern latitudes. The choice of self-identified FST category is influenced by a person's immediate environment. Therefore, we confirmed the relative nature of the FST scale and the need to standardise the skin phototype assessment procedure.