Sites where improper disposal of lead acid batteries has occurred, or where mercury was once used in mining retort operations, typify sites where heavy metals are a concern. Chromium and arsenic also show up as heavy metal contaminants. Threats to human health posed by these hazardous substances cover a wide range. Many of the chlorinated hydrocarbons and some of the heavy metals are know to be carcinogenic. A wide range of acute and chronic health effects may result from exposure to other compounds.
Some compounds present both a carcinogenic and chronic health risk.
In some cases the most important factors to consider in weighing the effects of contaminants may be ecological rather than human health based. This may be particularly true in remote locations where exposure to humans is less likely. In Alaska, about one-third of the sites in the ADEC inventory are on federal lands, with most of these on military bases. The rest are owned by the state and local governments. ADEC participates with other local, state and federal agencies in cooperative cleanup operations.