The World Health Organization's Environmental Health Criteria Programme (EHC) was initiated in 1973 to assess information on the relationship between exposure to environmental pollutants and human health, and to establish guidelines for setting exposure limits. The EHC monographs series provide a thorough evaluation of risks and aim to assist national and international authorities in making risk management decisions. This book contains a critical review of the risks posed by exposure to zinc, an element which is found in most rocks and many minerals., Zinc is a common element in the natural environment. Apart from artificially reduced zinc metal, it exists in the divalent state Zn (II) in the environment and it is an essential element for most organisms. It is well known that zinc deficiency causes numerous effects in humans, including neurosensory changes, growth retardation and delayed wound healing, but most people obtain sufficient amounts of zinc from their diet to avoid these effects. On the other hand, it is reported that high doses of zinc cause gastrointestinal distress, nausea and diarrhoea. This book evaluates the risks to human health and the environment posed by exposures to zinc. Overall evaluation suggests that normal, healthy individuals not exposed to zinc in the workplace are at potentially greater risk from the adverse effects associated with zinc deficiency than from those associated with normal environmental exposure to zinc because of its relatively low toxicity in humans and the limited sources of human exposure.