[Continuous inhalation of small amounts of formaldehyde: experimental study in the rat]

The results of experiments on the Rat, about the effects of continuous inhalation of 1.60, 4.55 and 8,07 ppm of formaldehyde, are reported: 150 SPF male rats were observed during one and an half to three months. These experiments concerned the clinical observation of the rats, their body weight and food intake, the relative weights of their lungs, liver, kidneys and spleen, the number and activity of their alveolar macrophages harvested by pulmonary washing. 1degree At 1.60 ppm it was only observed a yellowing of the hair of the intoxicated rats. 2degrees At 4.55 ppm, besides, the body weight of the intoxicated animals became significantly lower than the controls. 3degrees At 8.07 ppm, in addition to those differences, it appeared signs of irritation in the upper respiratory tract and in the eyes of the intoxicated rats, a significant underfeeding and a percentage of liver weight lower than the controls. Besides, the relative number and the phagocytic ability of alveolar macrophages of intoxicated rats was significantly lower than the controls. It was not observed the phenomena of adaptation previously described in the experimental rat intoxication by acrolein.