The advantageous properties of polyvinyl chloride plastics make these materials indispensable at all levels of human life, and there is no reason to believe that the upward trend of their use will change. One third of most polyvinyl chloride plastics consists of plasticizers, mostly phthalate esters, which may migrate out contaminating our environment and consequently our bodies. Experimental results indicate that chronic exposure to phthalic esters may be responsible for a number of adverse health effects. Phthalates change the structure and function of the liver in a profound manner by inducing peroxisomes, mitochondria and enzymes which participate in fatty acid transport and beta-oxidation. Prolonged administration of phthalate esters, in doses comparable to those occurring in human exposures, seems to have an accumulative effect on the liver. Liver biopsies taken from dialysis patients show peroxisome proliferation which again warn of the possibility that human health may be influenced by plasticizers.