PADIMATE O SUNSCREEN CONTRIBUTION TO NITROSAMINE FORMATION
PADIMATE O SUNSCREEN CONTRIBUTION TO NITROSAMINE FORMATION will be studied jointly by industry and FDA. The study will determine whether the nitrosamine NPABAO "is, in fact, present in the sunscreen products containing the ingredient Padimate O, and, if so, whether it constitutes any public health risk," the Cosmetic, Toiletry and Fragrance Association noted in an Aug. 11 letter to the agency. The letter outlines an agreement reached between CTFA and OTC Drug Evaluation Director William Gilbertson at an Aug. 10 meeting. The meeting came after FDA notified CTFA in July that it is planning to reopen the sunscreen monograph to address the "potential problem" of carcinogenic nitrosamines in sunscreens containing Padimate O ("The Pink Sheet" Aug. 7, T&G-7). CTFA and FDA have also agreed to share the results of photostability tests designed to ascertain whether NPABAO is stable on exposure to ultraviolet light. CTFA questioned the procedure used by FDA to determine the presence of NPABAO (N-nitroso-N-methyl-p-amino-benzoic-acid octyl ester) in sunscreens and instead, proposed development of a new test method and a collaborative protocol designed to validate the method. An evaluation of FDA's assay method by suncreen maker Schering-Plough has led CTFA to conclude that "the analytical method [used by FDA] creates conditions in which artifact nitrosation can occur in products containing Padimate O, and that the analytical method may itself produce levels of NPABAO not present in the product." CTFA's new method will be based on a procedure developed by Plough. The procedure is "more useful and appropriate" for detecting NPABAO because it "does not generate nitrosamines as an artifact of the methodology," according to CTFA. Following approval by FDA, the validation testing will be conducted by "at least two industry or industry-sponsored laboratories and FDA's laboratories," CTFA said. The NPABAO standard will be supplied to the participating labs by FDA, the trade association noted. Results will be reviewed jointly and submitted for inclusion in the administrative record. Preliminary results of FDA's method, announced in May 1988, identified the presence of NPABAO in 14 of 17 commercially marketed Padimate O-containing sunscreens at levels ranging from 60 to 1,960 ppb. CTFA has informed the agency that the ingredient is used in 70% to 80% of the sunscreens on the market in the U.S.
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