Lung, Bladder, and Kidney Cancer Mortality 40 Years After Arsenic Exposure Reduction

Abstract

Background: Region II in northern Chile (population 442 570) experienced a sudden major increase in arsenic water concentrations in 1958 in the main city of Antofagasta, followed by a major reduction in exposure when an arsenic removal plant was installed in 1970. It provides a unique opportunity to study latency effects of exposure to arsenic, and this is the first study with mortality data up to 40 years after exposure reduction.

Methods: We previously identified high mortality rates in Region II up to the year 2000. Here we present rate ratios (RRs) for Region II compared with all the rest of Chile from 2001 to 2010, and with unexposed Region V (population 1 539 852) for all years from 1950 to 2010. All statistical tests were one-sided.

Results: From 2001 to 2010, comparing Region II with the rest of Chile, lung and bladder mortality were still greatly elevated (RR = 3.38, 95% confidence interval [CI] = 3.19 to 3.58, P < .001 for lung cancer in men; RR = 2.41, 95% CI = 2.20 to 2.64, P < .001 for lung cancer in women; RR = 4.79, 95% CI = 4.20 to 5.46, P < .001 for bladder cancer in men; RR = 6.43, 95% CI = 5.49 to 7.54, P < .001 for bladder cancer in women). Kidney cancer mortality was also elevated (RR = 1.75, 95% CI = 1.49 to 2.05, P < .001 for men; RR = 2.09, 95% CI = 1.69 to 2.57, P < .001 for women). Earlier short latency acute myocardial infarction mortality increases had subsided.

Conclusions: Lung, bladder, and kidney cancer mortality due to arsenic exposure have very long latencies, with increased risks manifesting 40 years after exposure reduction. Our findings suggest that arsenic in drinking water may involve one of the longest cancer latencies for a human carcinogen.

Figure 1.

Map of Chile.

Figure 2.

Arsenic concentrations in the drinking water in Region II of northern Chile for 1930–2010. New arsenic-contaminated water sources were used beginning in 1958, and an arsenic removal plant was installed in 1970, with improvements in arsenic removal efficiency since then.

Figure 3.

Age-adjusted rate ratios for lung cancer mortality for Region II (arsenic-exposed) compared with Region V (unexposed), Chile (1950–2010). Results for men and women age 30 years and older are presented separately. Each point represents an estimate for five years and is plotted at the midpoint of the five-year period, starting with the estimate for 1950–1954, which is plotted at the midpoint year 1952. The error bars represent the 95% confidence intervals.

Figure 4.

Age-adjusted rate ratios for bladder cancer mortality for Region II (arsenic-exposed) compared with Region V (unexposed), Chile (1950–2010). Results for men and women age 30 years and older are presented separately. Each point represents an estimate for five years and is plotted at the midpoint of the five-year period, starting with the estimate for 1950–1954, which is plotted at the midpoint year 1952. The error bars represent the 95% confidence intervals.