The report reviews the manner in which chemical contaminants found in nonoccupationally exposed U.S. residents enter the environment and subsequently human tissue. Approximately 100 contaminants are treated. Sources of literature used in the survey covered a 30-year period, the bulk of which was published within the past decade. Contaminants discussed include organochlorine, organophosphorus, carbonate, and miscellaneous pesticides; polychlorinated and polybrominated biphenyls and terphenyls; halogen compounds; asbestos; mercury, lead, zinc, cadmium, copper, manganese, molybdenum, selenium, arsenic, antimony, thallium, chromium, cobalt, nickel, vanadium, beryllium; and others. Production; use; entry into the environment; entry, metabolism, and effects in man; and description and evaluation of methods of analysis and validity of the data are the chief aspects treated. For pesticides, indiscriminate use is the chief means of environmental entry. Entry into man is by ingestion of particulate residues or through foods, particularly fat-containing animal products. Sources of environmental entry for metals and other elements are burning of fossil fuels, industrial operations, dissipative uses, and natural inputs. Entry in humans occurs largely by exposure to airborne particulates, and to a lesser degree through food and water. Some elements are essential or beneficial at one level of concentration and toxic at another. Discussions of the status of elements from this standpoint are included where appropriate.