Repeated exposure to acetaldehyde vapor. Studies in Syrian golden hamsters.

The subacute inhalation toxicity of acetaldehyde was examined with four groups of 20 hamsters each, exposed repeatedly to acetaldehyde vapor at concentrations of 0, 390, 1,340, and 4,560 ppm (six hr day, five days/week) for a 90-day period. The highest level induced growth retardation, ocular and nasal irritation, increased numbers of erythrocytes, increased weights of heart and kidneys, and severe histopathological changes in the respiratory tract that mainly consisted of necrosis, inflammatory changes, and hyper- and metaplasia of the epithelium. The upper segments of the respiratory tract were much more severely injured than the lower parts. At 1,340 ppm treatment-releated changes included increased kidney weights in males and slight hyper- and metaplastic changes of the tracheal epithelium; 390 ppm was considered a no toxic effect level.