USE OF ANTI-IRRITANTS IN COSMETIC FORMULATING 337 Mineral Oils An exceptionally well controlled study by Hoekstra and Phillips (33) showed that certain mineral oil fractions are highly irritating when ap- plied topically to guinea pigs. All aromatic fractions caused problems mid-range parafiSnic material (b.p. 322 333øC) was the worst of the nonaromatic fractions. Mixing these with high boiling (over 402øC) fractions reduced irritation to zero, showing the dramatic anti-irritant activity of these high boiling point fractions. Rieger and Battista (34) reported that skin irritation [rom products containing combinations of light mineral oil with sodium lauryl sulfate, amine soaps or nonionic wetting agents can be alleviated by switching to a heavier grade mineral oil. Mirahogs Miranol 'C2M Concentration is a patented (35) lauroylcycloim- idinium amphoteric surfactant (Miranol Chemical Co. Inc.) which ap- parently reduces eye irritation by directly complexing certain irritants. For example, Miranol 2MCA Modified (36), an equimolar complex of Miranol C2M with sulfated lauryl alcohol, is completely nonirritating to the eyes, according to data published by the manufacturer. It was shown earlier in this paper that 0.14% C2M reduced eye irritation of an aerosol cologne to one-third and that of a highly mentholated (0.7% menthol) alcoholic product to zero. Miranol C2M was not particularly effective as the sole anti-irritant in an antiperspirant but did further reduce total eye irritation somewhat when used as an "auxiliary" anti -irritant. Myristyl Lactate This ester reportedly is useful at a level of 0.25% in alcoholic body rubs to reduce stinging. Similarly, it can be used in alcoholic after- shaves. However, when added at a level of 5% to an alcoholic anti- perspirant, it significantly raised eye irritation. Polypropylene Glycol The P 2000 grade (Dow Chemical Co.) of polypropylene glycol re- duced eye irritation and completely eliminated skin irritation in colognes, as described in the preceding pages.

338 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Polyvinyl Pyrrolidone (P VP) The basic patent showing this material's detoxifying and anti- irritant properties (when complexing iodine and other halogens) was granted to Shelanski (1) in 1956. This patent states that the PVP- iodine complex has only 10% of the toxicity of free iodine and none of its skin irritation or sensitization properties. The complex is odorless and nonstaining, yet has more antiseptic activity than iodine itself. Guttman and Higuchi (37) pointed out that phenols are also strongly complexed by PVP, retaining their activity while showing reduced irritation potential. Wilkinson et al. (38) gave details of repeated insult testing, showing reduction in reactions to both hexachlorophene and bithionol in the presence of PVP. Burnette (39) described work of Chambron wherein induction of cancer by 3,4-benzopyrene injections was reduced from 100% when the vehicle was vegetable oil to 10.7% when 40% aqueous PVP was used as the vehicle. Prescott et al. (40) make many unsupported claims that PVP can reduce allergic response and the "irritating effects of skin fatiguing agents" in cosmetics. On the other hand, PVP has been shown pre- viously (41) to reduce eye irritation in shampoos. It was not found too useful (cf. preceding pages) at 0.3% in reducing eye irritation caused by menthol but did reduce the skin and eye irritation of several cologne formulations. Orentreich (42) tested 2% paraphenylene diamine (PPD), with and without 1% PVP-K30, on 14 subjects, six of whom were known sensitives to PPD. Reactions to both preparations were almost identical, and it appears that PVP does not "desensitize" PPD. Tertiary A mine Oxides Drew and Voss (2) disclosed interesting irritation data in a Canadian patent covering combinations of tertiary amine oxides and alkyl benzene sulfonates in detergent formulations. Ratios of lauryldimethylamine oxide to sodium dodecylbenzene sulfonate varying from 1:4 to 2: 1 gave the least irritation. The cetyl and myristyl analogues of this amine also increased the mildness of the sulfonate detergent. Thiodioglycolic Acid A British patent (3) claims that this acid and its amide or esters (at 0.2-10%) reduce irritation of aqueous or alcoholic hair preparations, including those containing cationic surfactants. The only substantiated data concerning the efficacy of this compound are those described in the