648 R. S. Berger, Z A. Mezick and C. M. Papa The film-forming product did not elicit a sensitivity response to 48 h occlusive tests in four subjects known to be allergic to acrylates. Clinical use tests confirmed that octyl dimethyl PABA did not produce facial irritation with sweating and swimming, a problem seen with amyl dimethyl PABA (6-8). Because it is anticipated that patients may use the product repeatedly, a subtotal inunction (abuse) test was conducted on twenty-one subjects. In this test, the product was applied to the arms, legs and back for 28 con- secutive days. Complete physical exams and laboratory evaluations were carried out at biweekly intervals. No local or systemic toxicity was noted. CLINICAL EFFICACY Double blind studies in Arizona (forty-seven subjects) and Florida (sixty-two subjects) compared the efficacy of the film-forming product to competitive products. Although no significant differences were observed in ordinary sunbathing or exercising, the film- forming sunscreen provided significantly better protection from sunburn than the other commercial products after 60 min swimming in two fresh water swimming pool tests and one salt water test (Table VII). Table VII. Clinical sunscreen studies for sunbathing plus swimming (1 h) erythema No of Study Subjects A B C D E Phoenix 23 1.7 2.7 2.8 2-9 2.9 Bradenton 12 1.4 2.6 2.9 3.0 3.0 Holmes Beach 25 1.9 2.5 2.8 * 3.0 A, 3.35/oo octyl dimethyl PABA plus film-former (lotion) B, 3.0• amyl dimethyl PABA plus 3.0• glyceryl PABA (lotion) C, 5'0• PABA (hydroalcoholic lotion) D, 10.05/oo sulisobenzone (lotion) E, placebo (no sunscreen). * Not tested. Erythema was graded on a scale of 0-3 (0, none 1, mild 2, moderate 3, severe). CONCLUSIONS Controlled laboratory and clinical studies, show that a sunscreen preparation containing 3'3•o octyl dimethyl PABA and an acrylate film-forming polymer is highly water- resistant and provides sunburn protection while permitting gradual tanning during swimming, sunbathing and exercising. It has little potential for irritation or adverse side effects and it does not unduly irritate inflamed skin or interfere with normal water loss from the skin. It remains steadfast during swimming but is easily removed with soap and water. This cosmetically pleasing product can easily be applied evenly to all body areas due to the oil in the water vehicle. It is invisible on the skin when dry and does not strain most clothing. Thus, it is well suited for daily use as well as for people who enjoy swimming and water sports. REFERENCES 1 Sams, W. M., Jr. In Fitzpatrick, T. B., Pathak, M. A., Harber, L. C., Seiji, M. and Kukita, A. Sunlight and Man 143 (1974) University of Tokyo Press, Japan. 2 Cumpelik, B. M. Analytical procedures and evaluation of sunscreens. J. Soc. Cosmet. Chern. 23 333 (1972). 3 Owens, D. W., Knox, J. M., Hudson, H. T. and Troll, D. Influence of wind on ultraviolet injury. Arch. Derrnatol. 109 200 (1974).

Water-resistant sunscreen-preparation 649 4 Owens, D. W., Knox, J. M., Hudson, H. T. and Troll, D. Influence of humidity on ultraviolet injury. J. Invest. Dermatol. 64 250 (1974). 5 Harris, D. R., Polk, F. and Willis, I. Evaluating sweat gland activity with imprint techniques. J. Invest. Dermatol. 58 78 (1972). 6 Wilson, W. W., Quero, R. and Masters, K. J. The search for a practical sunscreen. South. Med. J. 59 1425 (1966). 7 Parrish, J. A., Pathak, M. A. and Fitzpatrick, T. B. Facial irritation due to sunscreen products. Arch. DerrnatoL 111 525 (1975). 8 Frosch, P. J. and Kligman, A.M. A method for appraising the stinging capacity of topically applied substances. J. $oc. Cosmet. Chem. 28 197 (1977).