The objectives of the proposed research are the study of the effect of polyhalogenate aromatic hydrocarbons on iron absorption and other intestinal mechanisms using duodenal loops and total body counting in vivo and everted gut sacs in vitro. Preliminary data demonstrate that a single oral dose of a number of these compounds stimulates iron absorption and alter iron metabolism in rats. These compounds will be used to further characterize the absorptive mechanism for iron and its control processes by determining the structure-activity relationship for the various hydrocarbon congeners. Mutant mice with defects in their iron adsorptive mechanism will be studied with the hydrocarbons to determine the specificity of the compounds for the separate parts of the absorptive pathway and its controls. Intestinal and hepatic enzyme induction will be measured as benzo(a)pyrene hydroxylase (aryl hydrocarbon hydroxylase) concurrently in order to correlate the stimulatory effect on iron transport with the known enzyme-inducing properties of these compounds. Studies of additional hydrocarbons, especially flame retardants, will be done for their acute effects on iron and calcium transport. The flame retardant, polybrominated biphenyl, stimulates iron absorption when given in small doses for several weeks. Additional long-term, low-dose studies are planned with this and other pollutants to determine the minimal dose and time necessary to affect iron adsorption. Serum iron and total iron binding capacity will also be studied in order to detect evidence for alterations in iron metabolism. Since most of these hydrocarbons are commonly used industrial products or by-products, environmental contamination is a major public health concern and studies have centered on their potential carcinogenicity, mutagenicity and teratogenicity. These studies may provide evidence to suggest an additional health hazard, stimulation of iron absorption.