4-Amino-2-Hydroxytoluene is a substituted aromatic compound used in the formulation of permanent hair dyes, colors and tints. 4-Amino-2-Hydroxytoluene is used as a coupler in cosmetic hair dye formulations. The compound has a low oral toxicity in animals and has no significant mutagenic or teratogenic effects. The compound, at most, is a weak skin and eye irritant and, at most, a weak sensitizer. Carcinogenic skin painting studies of hair dyes containing this compound were negative. A variety of epidemio-logic studies have given no indication of a carcinogenic effect from the use of hair dyes.

Raspberry ketone (4-(4-hydroxyphenyl) butan-2-one; RK) is a major aromatic compound of red raspberry (Rubus idaeus) and is marketed on the Internet as a food supplement. The FDA classified it as GRAS (Generally Recognized as safe) food additives during the 1960s. The structure of RK is similar to the structures of capsaicin and synephrine, compounds known to exert anti-obese actions and alter the lipid metabolism. It was shown, that RK also decreased the weights and hepatic triacylglycerol content in rodents after they had been increased by a high-fat diet. Recently was discovered, that RK may exert anti-adipogenic effects through modulation of the HO-1/Wnt/beta-catenin signaling pathway. Investigations of raspberry ketone in quantitative structure-activity relationship (QSAR) models indicated potential cardiotoxic effects and potential effects on reproduction/development. Taking into account the high intake via supplements, the compound's toxic potential should be clarified with further experimental studies. In UK the pure compound is regarded as novel food requiring authorisation prior to marketing but raspberry ketone is not withdrawn from Internet sites from this country.