Substitution of ethylene with halogen atoms leads to a highly effective compound with a strongly lipophilic character. The most important solvent in the dry cleaning process is tetrachloroethylene (PER). Owing to its physical-chemical properties, it has become a ubiquitous environmental pollutant. The uptake of small amounts of PER through polluted drinking water does not lead to liver damage as originally suspected. On the one hand, PER is taken up by erythrocyte membranes, on the other, it interacts with chylomicrons. Thereby two transportmechanisms are provided by for PER. Consequently, various physiological functions of both transport systems are disturbed. The erythrocytes increasingly disintegrate and are broken down in the spleen. Of all organs, the spleen shows the highest concentration of PER. Also, disturbances in the lipid metabolism occur because chylomicrons are broken down at a slower rate. Thereby, serum triglyceride concentration increases. These lipids are increasingly stored in the fatty tissue leading to the high accumulation of PER. A toxicological evaluation of chlorinated hydrocarbons should therefore take into account the changes in the blood system and in the lipoprotein metabolism.