CDC_eHealthHow does the environment affect your health? Find out on the new Tracking Network at http://tinyurl.com/neppy9.
They've got information by location, source (water, air...) and type of disease.
For instance I can pull up Massachusetts
Then Content area well water, levels of contaminants in well water and finally arsenic. I found via independent testing that my well has As in it. Might be a useful tool for some health data, although it appears there's not much in it yet.