title: Long-lasting pigmentation more than its intensity is a reliable indicator of skin sun resistance.
abstract: BACKGROUND
  The currently adopted method for predicting sun sensitivity is Fitzpatrick's classification which however is based on self-reported burning tendency and tanning ability.
  
  
  OBJECTIVE
  Determination of the individual UV susceptibility based on non-subjective parameters.
  
  
  METHODS
  Minimal erythema dose (MED), intensity and duration of pigmentation on days 5, 9 and 16 following 1 MED and the levels of the melanin marker pyrrole-2,3,5-tricarboxylic acid (PTCA) were analysed in non-red-haired subjects (50, aged 20-46 years).
  
  
  RESULTS
  Phenotype groups or phototypes showed a good correlation with PTCA yields and the persistence of pigmentation on day 16, but not with MED values. MED values did not show a significant correlation with PTCA yields. On the other hand, high values on day 16 were exhibited only by subjects having PTCA values higher than 200 ng/mg.
  
  
  CONCLUSIONS
  Measurement persistence of pigmentation on day 16 represents a non-invasive and easy-to-perform method to evaluate photoprotection in those individuals escaping straightforward classification based on phenotype or anamnesis.
authors.affiliation: Azienda Sanitaria Locale, ASL NA1, Università degli Studi di Napoli Federico II, Napoli, Italy.
authors.forename: Enrico M
authors.initials: EM
authors.lastname: Procaccini
authors.forename: Alessandra
authors.initials: A
authors.lastname: Napolitano
authors.forename: Lucia
authors.initials: L
authors.lastname: Panzella
authors.forename: Emilia
authors.initials: E
authors.lastname: Prizio
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Monfrecola
mesh_terms: D000328:Adult; D004307:Dose-Response Relationship, Radiation; D004890:Erythema / Q000209:etiology*; D005260:Female; D006197:Hair / Q000737:chemistry; D006801:Humans; D008297:Male; D008543:Melanins / Q000032:analysis; D008875:Middle Aged; D011836:Radiation Tolerance / Q000502:physiology; D012867:Skin / Q000528:radiation effects*; D012880:Skin Pigmentation / Q000502:physiology* / Q000528:radiation effects; D013053:Spectrophotometry; D013997:Time Factors; D014466:Ultraviolet Rays / Q000009:adverse effects*