I can recommend a couple of sources that MacKinnon Simpson might
find
useful in trying to establish the link between tuberculosis and the
printers' trade: David Rosner and Gerald Markowitz, Deadly Dust:
Silicosis and the Politics of Occupational Disease in Twentieth-Century
America (Princeton University Press, 1991); and Michael E. Teller, The
Tuberculosis Movement: A Public Health Campaign in the Progressive Era
(Greenwood Press, 1988). Both of these sources provide a historical
overview of the medical community's understanding of tuberculosis, and
they investigate the links between the workplace and a variety of lung
diseases that were often classified as t.b. I don't know that much about
the printing trade, but I would guess that if there was a high incidence
of tuberculosis among printers, it may have something to do with the
interconnections of fumes, coughing, and spitting in the workplace. If
you can't find the answer to your question in these sources, you might
consider posting a request on H-Labor.
        Good luck.

        Gregg Andrews
        Southwest Texas State University