Two different experiments on rats were carried out: an acute intoxication causing clinical symptoms and a subchronical intoxication without any symptoms. After the acute experiment an increase of hemoglobin- and hematocrite values as well as of the mean corpuscular hemoglobin concentration was found. These differences are interpreted to be an increased erythropoiesis after hypoxia. Following the subchronical experiment the parameters mentioned above had decreased. These results linked up to anisocytosis, poikilocytosis and/or polychromasia in 30% of the treated animals and allow to assume a disorder of erythropoiesis. The results require to take in consideration a prophylactic hematological survey of long-term exposed people.