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Quantification
and Prediction of sun-reactive skin type.
Kollias, Nikiforos 1
J&J Consumer Products Worldwide, Skillman, NJ1
Abstract-
The original skin typing classification scheme proposed by T.B. Fitzpatrick
was based on a history-taking interview with a patient. Skin types covered
the range I-VI from the most sensitive to the least. This scheme served
well the determination of dosimetry for PUVA and for risk factors associated
with non-melanoma skin cancer. Several alterations have been proposed
to the original scheme all with the intend of making the decision taking
process more objective. There are two approaches to classifying individuals
by skin type, quantification of static parameters such as pigment level
of unexposed skin sites, stratum corneum thickness, or quantification
of skin reactivity such as Minimum Erythema Dose (MED), UV induction
of pigment production, UV induction of stratum corneum thickening etc.
Invasive approaches include the quantification of DNA damage, sunburn
cell production, alterations of Langerhans cells and the expression
of cytokines. In testing the reactivity of the skin both the slope of
the dose-response curve for erythema and the persistence of erythema
following a 2 MED exposure have been considered. The reactivity of skin
(for both erythema and pigmentation) has been studied with monochromatic
radiation. Radiation at 305 nm was the most skin type sensitive for
erythema and radiation at 365 nm the most skin type sensitive for pigmentation.
The threshold immediate reactions of skin to UVA radiation have been
shown to be skin type independent while exposures to superthreshold
levels show a weak positive correlation with pigment level. Changes
in the pigment signatures with time post exposure show a correlation
with skin type. Thus while we have succeeded in quantifying a wide array
of parameters of human skin we have not been successful in defining
the combination of parameters that best reflects the skin typing classification
originally proposed by T.B. Fitzpatrick. How can a skin type meter become
an attainable goal?
Keywords: skin
types, risk factors, pigmentation, quantification
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