A New Approach in the Determination of Eumelanin in Human Hair Using near Infrared Spectroscopy

Abstract

Page 10 NIR news Vol. 16 No. 6 (2005) The aetiology of skin cancers is a complex interaction between genetic characteristics (phenotypically expressed by skin complexion) and exposure to sun. These two factors, complexion and exposure to sun, modulate the risk of different tumours in a different way. In detail, for melanoma, risk is associated with fair complexion (light blonde or red hair, high number of naevi and freckles, tendency to sunburn) and with intense and intermittent exposures like those experienced during holidays. Risk profiles are defined by semi-quantitative empiric parameters (scale of hair, eye and skin colour, acute reactivity scale, such as MED, Minimal Erithemal Dose) for the tendency to sunburn. Knowledge of the biochemistry of skin pigments, the melanins, has made it possible to identify a biological marker. Melanins are biopolymers present in the hair and epidermis. There are two distinct types of melanin pigments: the eumelanins, efficient in photo-protection and responsible for black and brown colour and the pheomelanins, bad at photo-protection and responsible for yellow and reddish colour. Most Caucasian populations have intermediate skin and hair colour and present these two kind of pigment in different ratios. This study about the distribution of melanin pigment in the population in general and in groups of subjects with different cutaneous tumours is an original work, starting from results obtained in the biochemical field. The turning point from empirical characterisation to biochemical characterisation of phenotypes by the quantitative determination of melanins in human hair can lead to the selection of groups with an elevated risk of cutaneous tumours. In these groups of people it will be possible to carry out more thorough diagnostic tests (dermatological inspection of skin). A multicentric case-control study was carried out in different European countries. Three groups of about 300 cases were recruited for each cutaneous cancer (cutaneous melanoma, squamous cell carcinoma and basal cell carcinoma) and 300 controls. For each group of people, in addition to data concerning phenotype and sun exposure Eumelanin in Human Hair