Potential health impacts of heavy-metal exposure at the Tar Creek Superfund site, Ottawa County, Oklahoma.

The potential impact of exposure to heavy metals and health problems was evaluated at the Tar Creek Superfund site, Ottawa County, Oklahoma, USA. Observed versus expected mortality was calculated for selected conditions in the County and exposed cities. Excess mortality was found for stroke and heart disease when comparing the exposed County to the state but not when comparing the exposed cities to the nonexposed rest of the County. However, sample sizes in the exposed area were small, population emigration has been ongoing, and geographic coding of mortality data was incomplete. In an exposed community, 62.5% of children under the age of 6 years had blood lead levels exceeding 10 microg/dl. The relationships between heavy-metal exposure and children's health and chronic disease in adults are suggestive that a more thorough investigation might be warranted. A number of possible environmental and health studies are suggested, including those focusing on possible central nervous system impacts. Unfortunately, the exposed population is dispersing. One lesson learned at this site is that health studies need to be conducted as soon as possible after an environmental problem is identified to both study the impact of the most acute exposures and to maximize study sample size-including those exposed to higher doses-and minimize the loss of individuals to follow-up.