title: Water immersion does not alter the minimal erythema dose.
abstract: To determine the water resistance of a sunscreen, the COLIPA method requires the determination of two minimal erythema doses (MEDs): a static MED (MED(US)) and a wet MED (MED(UW)) (1). The MED(US) is used in calculating the static SPF; the MED(UW) is used in calculating the SPF after water immersion. Herein, we report that in the 107 subjects examined, the mean MED(US) (21.0±0.55 mJ) is not different from the mean MED(UW) (21.0±0.61 mJ). This shows that water immersion does not alter the minimal erythema dose and strongly suggests that the determination of two MEDs is unnecessary and that one should be eliminated. Eliminating one of the two MED determinations would increase the benefit/risk ratio of the COLIPA sunscreen water-resistance efficacy testing without harm to efficacy.
authors.affiliation: Consumer Product Testing Company, Inc., Fairfield, NJ 07004, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Caswell
authors.forename: Caryl
authors.initials: C
authors.lastname: Wood
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Maly
mesh_terms: D004890:Erythema / Q000139:chemically induced*; D006801:Humans; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water