The distribution of anthropogenic lead in the aquatic environment is governed by atmospheric input (leaded gasoline) and input from point sources (mining areas, smelters, factories producing chemicals and goods based on lead). The bioavailability of lead to organisms is a function of the primary and secondary speciation of lead. Dissolved chemical forms of lead are extremely toxic when present in high concentrations in an aquatic environment. Chronic toxicity occurs when lead is bioconcentrated in aquatic species over a period of time and when it is stored in internal organs. However, biomagnification has not been observed in the aquatic environment.