Metals in municipal landfill leachate and their health effects

The leachate from five municipal landfills (containing no industrial waste or sewage sludge) was studied in 1975 by the U. S. Environmental Protection Agency (EPA). Copper was not present in concentrations above EPA standards. Zinc concentrations decreased with age of the site and were below standards. The amounts of cadmium and chromium appear to vary greatly from site to site. Lead, selenium, iron, and mercury were present at each site in concentrations above standards, regardless of site age. Although raw leachate contains concentrations of heavy metals in excess of the drinking water standards, it is not clear how likely it would be for these recorded levels to be found in drinking water supplies or for contamination to reach the human body. Before leachate reaches an aquifer, it is subject to the attenuating effect of the unsaturated zone. If municipal solid waste is placed directly into ground water, or if leachate is allowed to drain directly into surface water, severe damage to water quality can result. Further study of the environmental effects of leachate are being undertaken by the Environmental Protection Agency.