-432 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS intervention of the bacterial flora will only affect it when it is excreted in the bile. The point emerges that there is so much splitting of these azo-linkages in the intestine that it would appear advisable to make special studies of the amine moteties that are formed. The same moiety is common to a number of colourings, and by undertaking a close study of these individual moteties, as regards their further metabolism and other 'effects in the body, one would be automatically clearing the way for a better under- •standing of many of the other colourings which have not been adequately studied -hitherto. With regard to the question of specifications, a description of a colouring which was in order ten years ago is not really satisfactory today, and one has a right as a toxicologist to insist on an accurate description of these materials by the latest ß available methods. As regards toxicological standards I think that the time has passed when the 'objective of toxicological testing was to bring about a negative result which acted as an assurance that everything was all right. Much more should be expected of toxi- cological testing, viz. a set of positive findings with regard to the metabolic fate and the influence of the test material on the animal. The effects of exposure are not necessarily toxic effects, but they are always there, and they should be found, because it is only by having positive findings that one has an assurance of safety. Purely negative findings leave the possibility that something of importance has been missed. We are often in a position now to derive positive findings by special methods if we really take the trouble, and this raises the question of a programme such as that ' of the Toilet Goods Association (U.S.A.) where the •learance of a number of cosmetics colourings is involved. If one examines what it is they have set out to' do, one finds that essentially they are trying to produce negative results. I do not blame them for this. At present this is a valid procedure, but it does raise the question whether this particular approach is really sufficient. Of course, as I have mentioned, where one is dealing with colourings which are only to be applied externally, and there is little or no chance of ingestion, one obviously does not require the same standard 'of toxicological evaluation, the same stringency of examination, that is needed for 'colourings intended for food all the same I think it is important to have an approach which seeks to provide a clear idea of what is happening rather than one that produces results which are almost completely negative. There is one point which I should like to stress again, viz. the distinction between primary and secondary effects in toxicology. I have illustrated these effects by reference to subcutaneous sarcomas produced by colourings and other materials. A great many valuable colourings have thus been labelled as carcinogenic, and we in this country suffer particularly from this outlook. Another important point I made, but only very passingly, is the fact that toxi- 'cological examinations are carried out on normal animals but in the case of man there is the chemical environment to be taken into account. By chemical environment I refer to natural constituents of food, other food additives, the exposure to various substances in the atmosphere, in drinking water, in the home, the consumption of drugs or alcohol. All these exposures have effects, many of which the body probably 'overcomes by physiological adjustments. The recognition of these changes, and the ability to distinguish them from pathological toxic effects often requires much more knowledge than we possess at present.

Book reviews GRAPHIC HANDBOOK OF CHEMISTRY AND METAL- LURGY. P.Y. Loung. Pp. 79 q- I!!. (1965). Chemical Publishing Company, New York. $10.00. The elements as arranged in the periodic table are the fundamental building stones of the material world. Although the study of these elements usually belongs to chemistry, the resulting data are essential to every branch of natural science. These have been plotted into graphs ,and the book contains 100 graphs of which 60 are periodic binary alloying graphs. In order to compare one graph with another con- veniently split pages combined with a ring binder are used. The graphs of the portant chemical, physical, mechanical, and metallurgical properties of the elements are presented. This book should prove to be most useful to scientists and many others through placing these well-organized graphs of the periodic properties of the elements at their fingertips. A. H. ADVANCES IN BIOLOGY OF SKIN. Vol. VII CARCINO- GENESIS. Editors: W. Montagna and R. L. Dobson. Pp. xiii q- 358. q- Ii!. (1966). Pergamon Press, Oxford. 110s. This is the seventh volume in the excellently produced and authoritative series of "Advances in Biology of Skin". Each of these provides a truly solid founda- tion of up-to-date thinking on the fundamental problems of skin physiology, the latest addition being no exception. It reprints the proceedings of a Symposium organized by the University of Oregon Medical School in April 1965 and has a number of distinguished contributors who are dealing with their own special fields of interest in considerable detail and with a wealth of practical research experience. Bearing in mind the long-term frequent usage of cosmetics and toiletries, it behoves the cosmetic chemist to treat the subject of carcinogenesis with due respect even though there are no known cases of malignancy arising from the use of our products. It is therefore desirable at least to become acquainted with the principles of cell biology and to appreciate the possible implications of molecular biology. As far as carcinogenesis is concerned, one of the most puzzling issues is the problem of tissue homeostasis or, to put it crudely, what is the normal mechanism for controlling the size of any organ in the human body. Professor 13ullough and Dr. Edna Laurence have studied this problem for many years and have worked out a fascinating series of hypotheses which are summarized in Chapter 1. The kinetics of epidermal reaction to carcinogens and other skin irritants (O. H. Iversen) has obvious implications for the cosmetic scientist and so has Bingham and Horton's contribution dealing with experimental observations related to occupational 433