The i, vivo SPF of the sunscreen formulations used in this study were determined
according to the European protocol (12). In some cases instead of ten volunteers the
studies were carried out with only five volunteers (as indicated in Table I). The formu-
lations used in the present study were all of the o/w-type (see Appendix II). In order to
increase the significance of this study, data from references 13 and 14 were also taken
into consideration. In all cases the amount of sunscreen formulation applied is 2 mg/cm 2,
which equals in terms of volume approximately 2 pl/cm 2. This in turn corresponds to
an average film thickness of 20 pm. The i, vivo data of reference 13 were measured
according to the COLIPA protocol, which implies the use of ten subjects and a confi-
dence interval smaller than +20%. The i, vivo data of reference 14 were obtained
according to the FDA protocol with a reduced number of volunteers (eight subjects
instead of 20). With eight subjects the confidence interval in most cases is smaller than
_+25%.