J. Soc. Cosmetic Chemists 18 421-432 (1967) (c) 1967 Society of Cosmetic Chemists of Great Britain The toxicology of materials artificial colouring L. GOLBERG* Delivered at the Symposium on "Colour", organised by the Society of Cosmetic Chemists of Great Britain in Eastbourne, Sussex, on 27th April 1966. $•raol•aia--The toxicology of artificial colouring materials is discussed in relation to the many practical problems that arise in safety evaluation. The importance is stressed of adequate knowledge of chemical composition and reliable standardization of the specification of material to be tested. General analysis of metabolic changes undergone by colourings in the intestine, liver and blood of experimental animals is followed by consideration of systemic toxicity and carcinogenicity. Special attention is given to the question of turnour induction by subcutaneous injection. Other aspects, such as effects on reproduction and the foetus, and mutagenesis are touched upon. Finally the question of dose-effect relationship is briefly considered. INTRODUCTION The use in the title of the term "artificial" might suggest that there is something especially toxic about such materials in comparison with colourings of natural origin. The simple fact is, of course, that what we do know about the toxicology of colourings relates almost exclusively to those of synthetic origin while those derived from natural sources, however naturrein they may be, represent practically unknown territory from the standpoint of the toxicologist. Thus, while it is the object of this paper to discuss the various ways in which artificial colour- ings and their breakdown products or metabolites may exercise deleterious influences on the body, it should be emphasized that such knowledge constitutes the essentiM basis for the assessment of hazard and reliable evaluation of safety-in-use. It is left to the reader to decide whether the public is better protected when such fundamental information is available than when the safety of the material is taken on trust because "nature made it." *British Industrial Biological Research Association, Carshalton, Surrey. [Now at Albany Medical College, New York, U.S.A.] 49.1

422 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS It is my intention as far as possible to avoid covering ground that was very adequately dealt with at the 1963 Symposium on "Toxicology of Cosmetic Matehals," and in particular my own contribution on "The assessment of safety-in-use: just how much is contributed by feeding tests in animals ?" (1). I am fortunate also in having Prof. Cainan dis- cussing reactions to colouring materials (2) and need not therefore elaborate on this aspect of their toxicology. This discussion will be principally concerned with food colourings, for that is the field in which there is most knowledge and experience. It does not follow automatically that acceptance for food use renders such colours safe for use in cosmetics. Some mention will be made of the additional tests involved to establish suitability for incorporation into formulations intended for external application. Specifications and impurities I need hardly stress the importance of knowing what we are testing when we undertake to study the toxicology of a material. While speci- fications are available for many synthetic colourings, particularly those used in food, they usually fall far short of what is desirable from the standpoint of the toxicologist. Not for him the pathetic charade of limits for lead, arsenic or copper, archaic devices intended to ensure good manu- facturing practice, and now quite wrongly interpreted as safeguards against toxic hazard. How adequate is the emphasis on limits for total amines or total ether extractable matehals ? This is the age of chromatography, and there is no reason why it should not be applied to separate, identify and ultimately to standardize the by-products that are present, so that their role in the production of biological effects may be accurately assessed. The time has long since passed when toxicological evaluation could be carried out "blind." If we are to make full use of recent advances in biochemical pharmacology we need to know all we can about the chemical composition of the matehal under investigation. A striking instance of the discrepancies between apparently authentic specimens of Ponceau 3R, recently reported by Hansen, et al (3), underlines the need to characterize most fully any colouring undergoing safety evaluation. METABOLIC CHANGES In the intestinal tract Colouring matters entering the gut are subjected to the action of acid, digestive enzymes and the gut flora. The degradation undergone as a