THE CHOICE OF PERFUMES FOR PRESSURIZED PRODUCTS 399 DR. W. MITCHELL: As some present here may recall, I was the author of the "public statement" about the adverse effect of certain perfume materials on pyrethrins. The lecturer is satisfied that the warning is groundless, but it was made by one with the advantage of wide experience not only with perfume materials but also with pyrethrum. Of course, a great many perfume materials do not have any effect on the pyrethrins, and if one is lucky enough to avoid using them, all will be well. As stated by the lecturer, acetophenone and diphenylmethane are two of these and they do also have a limited synergistic effect on the pyrethrins, though they are. not in the same high class of activity as the two synergists, Bucarpolate and piperonyl butoxide, normally used in this country. However, there are some perfume components that do have an adverse effect on the active principles of pyrethrum, though for obvious commercial reasons I am not permitted to name them. However, we have sounded the warning note. If others care to ignore it, or to prove to their own satisfaction that the danger does not exist--well, that is their affair. But the facts will not be altered ! THE LECTURER: I should like to say that no discourtesy was intended to you in respect of the "public statement". I was entirely unaware of its ultimate origin. We should be very unwise to disregard the views of someone so widely experienced as Dr. Mitchell. We agree with him that certain concentrated chemicals do have the adverse effect described but our extensive experience with the types of perfume compounds which would be offered for use in insecticides, has led us to the conclusion that no real practical hazard exists. MR. J. PICKTHALL: A few years ago we published results ls of tests on 13 perfumery chemicals in insect control formulations containing pyrethrums. These were tested in the presence and absence of the synergist piperonyl butoxide by topical application of micro doses to normal house flies. Of the compounds tested phenylacetaldehyde had a slightly detrimental effect on the pyrethrum potency. As pointed out in the paper, phenylacetaldehyde is an unlikely ingredient in an aerosol perfume. The tests involved employed 0.5% of the individual ingredient which greatly exceeds the amount which would appear in a compound perfume. An extension of this work was made by testing a bouquet made up of a number of synthetic chemicals, essential oils and isolates. Tests were made on a synergised pyrethrum mixture with and without perfume, sprayed from an aerosol in a 1,000 cu. ft. chamber. The perfumed samples revealed no reduction of potency. MR. B. H. LANGLEY: Whilst not wishing to take part in the epic struggle between Dr. Mitchell and Mr. Pickthall, I feel (since reference is made by

400 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS the lecturer in his paper to a patent with which my company is concerned) that I should inform those present that as the result of tests with a wide range of aromatic (perfumery) chemicals it was found that many had activat- ing and synergistic properties in relation to pyrethrins, and I would there- fore incline towards Mr. Pickthall's views rather than those of Dr. Mitchell. MR. A. HERZI(^: Could you please explain the reason for carrying out accelerated storage tests at 130øF. We normally carry out accelerated stor- age tests at 95øF, and I believe that this practice is fairly general throughout the industry in this country. There have been occasions in the past, where a satisfactory behaviour at 130øF was no criterion for subsequent performance in actual use. Likewise, failure at 130øF does not necessarily imply failure at room temperature. We have even been criticised for adverse comments on perfumes after 8 months' storage at 95øF, the comment being that "the probability of a pressure pack being so stored for any length of time in the United Kingdom is extremely unlikely, if not completely so." T•E LECTURER: The procedure mentioned in my paper was a very abbreviated indication of the general methods adopted. We ourselves endeavour to choose a testing system which is appropriate to the objectives in view. Tests at 95øF are not seriously accelerated and we use this tem- perature, alongside room conditions, as a measure of what happens under these conditions, not to forecast what might occur under other conditions. It is quite correct that occasionally a formulation which survives accelerated tests at 130øF does not emerge with equal success from a year's room tem- perature storage. But, as you have reported, the same applies to tests at 95øF. There is no safe substitute for actual tests under expected con- ditions but our experience shows that, in cases where the results of previous similar work are available, a fairly accurate forecast can be made on the basis of tests at 130øF and room temperature for one to two months. In fact, the temperature of 55øC (131øF) is mentioned as a very useful guide in Herzka, A. and Pickthall, J. Pressurized Packaging (Aerosols) 2nd Edition 196 (1961) (Butterworths, London). MR. J. PICIrTU^•J.: Whilst it is quite true to say that an accelerated test is not a guarantee of ultimate success, nevertheless, such tests are extremely valuable, especially in development work. We prefer 130øF to 95øF simply because the test period is correspondingly shorter. We have found that one month at 130øF indicates the probable results equivalent to one year or more at normal temperature. In development work a product (particu- larly a perfume) which is degraded at 55øC after one month can be regarded as unsuitable. Naturally there is a possibility of rejecting a product which would in fact have survived twelve months at normal temperature but such cases are few and far between. On the other hand, if a product does survive