Multi-ethnic Populations There has been a tendency to group all people of a similar ethnic group into a single category of SPT, which introduces potential bias into the subjective assessment of SPT by investigators. For example, Hispanic whites are often considered "brown" and assigned to Skin Type IV (Table 2). The heterogeneity of those with multi-ethnic backgrounds makes it difficult to assess susceptibility to skin cancer on the basis of skin color, which is predominantly determined by pigments such as hemoglobin, melanin, bilirubin, and carotene.