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

BACKGROUND/PURPOSE: 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 if PPF levels in the different FST categories are dependent on the investigated countries. METHODS: Volunteers (n=569) were recruited in Copenhagen (Denmark), Dublin (Ireland), London (England), Munster (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. RESULTS: Overall, there were statistically significant differences in PPF of the buttocks, inner arm, outer arm, forehead, chest and back between the five countries (P≤0.031). 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=0.723). However, it was statistically significantly different (P≤2.913*10-4 ) and country-dependent for those who identified as FST II-IV. CONCLUSION: Objectively measured sun sensitivity is higher (lower PPF) in northern compared to 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.