Arsenic in Private Wells Responsible for Surge in Bladder Cancer in New England

A new study published in the Journal of the National Cancer Institute has identified the cause of the high rates of bladder cancer cases diagnosed in the New England region of the United States: arsenic in drinking water from private wells.

The collaborative study, which included researchers from the National Cancer Institute (NCI), evaluated 1213 patients newly diagnosed with bladder cancer and 1418 controls, from the 3 states of New Hampshire, Vermont, and Maine. Trial participants were interviewed to identify their exposure to suspected risk factors for bladder cancer, including smoking, occupation, ancestry, use of wood-burning stoves, and consumption of various foods.

Senior study author Debra Silverman, ScD, chief of the Occupational and Environmental Epidemiology Branch, NCI, explained, “Although smoking and employment in high-risk occupations both showed their expected associations with bladder cancer risk in this population, they were similar to those found in other populations. This suggests that neither risk factor explains the excess occurrence of bladder cancer in northern New England.”

The authors found that the risk of bladder cancer increased with increasing water intake (P_trend = .003), and it was statistically significant among participants who had a history of consuming water from a private well (P_trend = .01). More specifically, shallow wells increased the risk (P_trend = .002) of the disease more than deep wells (P_trend = .48), pointing to the susceptibility of water in shallow well for contamination from manmade sources. A very important discovery was the association of wells used before 1960, when heavy pesticide use contaminated ground water in the region—those who consumed more water in those years (more than 2.2 L/day) had double the risk of light users (less than 1.1 L/day, P_trend = .01). Inorganic arsenic in drinking water is a well-recognized cause of bladder cancer when levels are relatively high (more than or equal to 150 µg/L).

Not being able to measure the cumulative exposure to arsenic over the participants’ entire lifetime, was a major limitation of the study.

Ongoing studies have been assessing the health risks of arsenic in the water supply of New England. Silverman is a part of the group conducting the New England Bladder Cancer Study, which was initiated in 2002 to determine the factors that contribute to the high rates of incidence of and death from bladder cancer in that region of the country.

Reference

Baris D, Waddell R, Beane Freeman LE, et al. Elevated bladder cancer in northern New England: the role of drinking water and arsenic. J Natl Cancer Inst. 2016;108(9):djw099.

doi:10.1093/jnci/djw099.