Health concerns in Woburn have been expressed since the late 1970's. A number of investigations have been conducted by the MDPH, the Centers for Disease Control (CDC), and Harvard University. Initial concerns focused on elevations in both total and male childhood leukemia incidence (the rate of occurrence of leukemia). For the period 1969-1978, childhood (aged 0-14 years) leukemia incidence was significantly elevated for males (9 observed, 3.1 expected), but not for females (3 observed, 2.2 expected). The ratio of male to female incidence was three to one. For the area of Woburn that received the greatest proportion of water from Wells G and H (census tract #3334), childhood leukemia incidence in males was 12 times higher than expected (5 observed, 0.4 expected, p < 0.001). A p value less than 0.001 means that the probability that the difference between the observed and expected values was due to chance is less than 0.1 chances in 100.
[Source: http://atsdr1.atsdr.cdc.gov:8080/HAC/PHA/wellsgh/wgh_p2.html#phi] (emphasis added)
The following map shows the locations of the defendants' properties (black diamonds: U = Unifirst, C = Cryovac / W.R. Grace, and R = Riley Tannery / Beatrice), municipal wells G & H (yellow circles), and the plaintiffs' homes (red circles):
Photograph from the collection of Professor Scott Bair, Ohio State University.
[Source: http://www.geology.ohio-state.edu/courtroom/pl&df-l.jpg]