Elevated Bladder Cancer In Northern New England: The Role Of Drinking Water And Arsenic

Debra SILVERMAN, National Institutes of Health, DHHS, United States
KARAGAS M. 2 , JOHNSON A. 8 , FRAUMENI J. 1 , HOOVER R. 1 , MCCOY R. 8 , ARMENTI K. 7 , HOSAIN M. 7 , ROBINSON G. 5 , MOORE L. 1 , ROTHMAN N. 1 , JACKSON B. 3 , SCHNED A. 3 , NUCKOLS J. 9 , WARD M. 1 , AYOTTE J. 5 , COLT J. 1 , SCHWENN M. 4 , BEANE FREEMAN L. 1 , WADDELL R. 2 , BARIS D. 1

1 Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, DHHS, Bethesda, Maryland, USA
2 Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
3 Dartmouth College, Hanover, New Hampshire, USA
4 Maine Cancer Registry, Augusta, Maine, USA
5 U.S. Geological Survey, Pembroke, New Hamphire and Reston, Virginia , USA
6 New Hampshire State Cancer Registry, Concord, New Hampshire, USA
7 New Hampshire State Occupational Surveillance Program, Concord, New Hampshire, USA
8 Vermont Department of Health, Burlington, Vermont, USA
9 Colorado State University, Fort Collins, Colorado, USA
10 Centers for Disease Control, Atlanta, Georgia, USA
11 Information Management Services, Calverton, Maryland, USA
12 Agency for Toxic Substances and Disease Registry, Environmental Protection Agency, Chicago, IL, USA

PURPOSE:  Bladder cancer incidence and mortality rates have been elevated in northern New England for at least five decades.   Our purpose was to identify the reasons for this excess with a focus on arsenic in drinking water from private wells, which are particularly prevalent in the region.
METHODS:  In a population-based case-control study in Maine, New Hampshire and Vermont, we interviewed 1,213 bladder cancer cases and 1,418 controls to obtain information on known and suspected risk factors. Arsenic concentrations were estimated by statistical modeling based on measurements in water samples from current and past homes.
RESULTS:  Bladder cancer risk increased with increasing water intake(P-trend=0.003).  This trend was significant among participants with a history of private well use(P-trend=0.011).  Among private well users, the trend with drinking water intake was apparent if well water was derived exclusively from shallow dug wells (which are vulnerable to contamination from manmade sources)(P-trend=0.002), but not if well water was supplied only by deeper drilled wells(P-trend=0.479).  If dug wells were used prior to 1960, when arsenical pesticides were widely used in the region, heavier water consumers(>2.2 L/day) had double the risk of light users(<1.1 L/day)(P-trend=0.012). Among all participants, cumulative arsenic exposure from all drinking water sources, lagged 40 years, yielded a positive risk gradient(P-trend=0.004); among the highest exposed participants(97.5th percentile), risk was twice that in the lowest exposure quartile(OR=2.2;95%CI=1.3-3.9).
CONCLUSIONS: Our findings support an association between exposure to low-to-moderate levels of arsenic in drinking water and bladder cancer risk in New England.  In addition, historical consumption of water from private wells, particularly from dug wells in an era when arsenical pesticides were widely used, was associated with increased bladder cancer risk and may have contributed to the New England excess. 
FUNDING:  Intramural Research Program of the US National Cancer Institute, Division of Cancer Epidemiology and Genetics.