"Herein lies the dominant irony of the state of British public health in the late 1840s. Just as Snow was concocting his theory of cholera as a waterborne agent that had to be ingested to do harm, Chadwick was building an elaborate scheme that would deliver the cholera bacteria directly to the mouths of Londoners... The first defining act of a modern, centralized public-health authority was to poison an entire urban population." The Ghost Map