Figure 5. SEM of polymeric film on human skin. Facing p. 646

Water-resistant sunscreen preparation 647 Table IV. Human sweat study Sweat gland activity after 7-day use for 12 h per day Active sweat glands/cm • Sweat gland activity after 4 days continuous use Active sweat glands/cm • Sunscreen Untreated Sunscreen Untreated Saran Subject treated control Subject treated control occluded 1 144 149 7 106 98 78 2 119 122 8 81 80 50 3 99 96 9 85 81 30 4 103 103 10 105 91 17 5 86 80 11 77 82 23 6 47 56 12 89 96 23 No significant difference between sunscreen treated and untreated control by one-way analysis of variance. Saran occluded and untreated control are significantly different by one-way analysis of variance. Table V. Hairless mouse study Average grade Condition A B C 150 rain uvl 0'7 2-3 6 30 rain water immersion 1.6 5.6 7 + 150 rain uvl A, 3'3•o octyl dimethyl PABA plus film-former (lotion) B, 5'0•o PABA (hydroalcoholic lotion) C, untreated: 0-3 mild 3-5, moderate 6-7, severe. SAFETY TESTS Safety tests including Draize (204 subjects), maximization (twenty-eight subjects), cumulative irritation (twenty-seven subjects), phototoxicity (ten subjects), and photo- allergy (twenty-five subjects) established that the film-forming sunscreen product had little or no allergy or irritancy potential. Only slight irritation was noted on stripped skin in human volunteers with the film-forming formulation, whereas, other commercial preparations produced moderate to severe irritation (Table VI). Table VI. Human stripped skin irritation Mean Level of Sunscreen products irritation score irritation A 0.3 Slight B 1'4 Slight to moderate C 2.7 Moderate to severe D 1.2 Slight to moderate E 3-1 Moderate to severe Untreated control 0'0 None A, 3.3• octyl dimethyl PABA plus film-former (lotion) B, 3'0}/o amyl dimethyl PABA plus 3.0•o glyceryl PABA (lotion) C, 5.0• PABA (hydroalcoholic lotion) D, 10'0•o sulisobenzone (lotion) E, 2'5•o amyl dimethyl PABA (hydroalcoholic lotion).