Current opinion on environmental contamination by lead is reviewed with particular reference to three major types of source, industrial and domestic. The implications for urban communities of continuous low-level exposure to lead are also examined in the light of recent research on the human response to lead at sub-critical levels. A significant contribution to environmental contamination arises from the lead smelting and refining industry, and the importance of this is examined by means of an actual case study. Using an interdisciplinary approach, a thorough investigation is made of the levels and distribution of lead in an agricultural ecosystem in West Yorkshire which is exposed to emissions from a secondary lead smelter. Comprehensive measurements were made of lead, and to a lesser extent of cadmium, in soils and vegetation surrounding the smelter; in addition, a permanent monitoring site was established in the area to measure fluctuations in the lead content of the ecosystem's major components. Topographical, climatological and hydrological factors were also examined in relation to the lead level measurements. A commercial wheat variety was grown and subsequently analysed to establish the probable morphological and physiological response of plants in general to soil and atmospheric lead burdens. The research shows that an integrated approach of this kind to heavy metal pollution is important in that it enables accurate identification of the parameters which can be used in a definitive monitoring programme. Furthermore, these are shown to be essential for the success of any procedures designed to control potential hazards associated with the industrial handling of lead.