plasma activities of alkaline phosphatase , ( ap ) , transaminases and total lactate dehydrogenase ( ldh ) with isoenzymes were determined in mice inhaling 50 and 550 ppm vinyl chloride ( vc ) . 
 the animals were also autopsied and the tissue pathology was studies . 
 the total ldh activity was elevanted in both dose groups along with a shift to cathodic enzymes . 
 ap was increased in animals exposed to 500 ppm and transaminases were not at all changed . 
 enzyme changes occurred after the appearance of tumors . 
 alveologenic adenomas occurred in all animals at the higher dosage and in about half of the animals inhaling the lower dose . 
 subperitoneal and subcutaneous hemangiosarcomas were frequent in both dose groups ; but especially among 50 ppm animals . 
 only one animal had a hemangiosarcoma of the liver . 
 no liver fibrosis was seen . 
 all primary subperitoneal and subcutaneous tumors were located in fat tissue . 
 telangiectasis was observed in two animals in the 500 ppm series . 
 the importance of blood vessel changes in the toxicology of vinyl chloride is discussed.imagesfigure 4.figure 5.figure 6.figure 7.figure 8 .