article_snippet: Dr Kathleen Smith of the US Geological Survey added: 'We have a two-pronged approach. '
article_snippet: the study presented at the 249th National Meeting & Exposition of the American Chemical Society (ACS) involved collecting samples from small towns in the Rocky Mountains, rural communities and big cities.
article_snippet: For a more comprehensive picture, the American Chemical Society (ACS) plan to combine the American Chemical Society (ACS) information with many years' worth of existing data collected by the Environmental Protection Agency and other groups at the Geological Survey.