The acute vapour inhalation toxicity of 2-butoxyethanol. Points considered when designing and conducting a study in Guinea pigs and evaluating existing inhalation toxicity data on low volatility solvents

Abstract

This publication reports the outcome of an acute inhalation toxicity study with guinea pigs by nose-only exposure to the substance 2-butoxyethanol at exposures close to the maximum attainable saturation vapour concentration. We describe the methods used to ensure exposure only to saturation vapour at a level as high as could be practically achieved whilst avoiding aerosol formation. We consider the practical difficulties and implications of testing substances at or close to their saturation vapour concentration and the criteria that should be used to critically assess such studies, especially with reference to the GHS (Globally Harmonised System) for classification and labelling, where a clear differentiation between gases, vapours and dust and mists applies. Guinea pigs showed no adverse effects when exposed for 4 h to the maximum attainable concentration of pure 2-butoxyethanol vapour. If guinea pigs are regarded as the most appropriate species to assess short term toxicity to humans from exposure to 2-butoxyethanol, because they are like humans not sensitive to haemolysis of red blood cells caused by exposure to the substance, then the data from this study shows that 2-butoxyethanol presents a low acute inhalation toxicity hazard.

Keywords: 2-Butoxyacetic acid; 2-Butoxyethanol; Acute toxicity; Classification; EGBE; Ethylene glycol butyl ether; Ethylene glycol monobutyl ether; Guinea pig; Hazard; Inhalation; Nose-only; Saturated vapour concentration; Vapour pressure.