The toxic effects of 2-methylbutyraldehyde (isovaleraldehyde), arising from the accidental contamination of a laboratory atmosphere, are described in six out of a group of seven chemists. These were mainly tightness in the chest, irritation of the upper respiratory tract, cough, dyspnoea, marked loss of energy and weakness, dizziness, headaches, profuse perspiration, tachycardia, nausea, vomiting, diarrhoea, anorexia, somnolence, sometimes insomnia, and in one case a partial pneumothorax.

All recovered rapidly when removed from the exciting cause.