Arsenic in Drinking Water and Lung Disease in Chile, California and Nevada

Millions of people are exposed to arsenic in drinking water. An ancient poison, arsenic occurs naturally in groundwater and geothermal springs. Removing arsenic from drinking water costs about ;Arsenic in drinking water causes cardiovascular death, cognitive deficits in children, reproductive problems, and cancer. Surprisingly, many studies have shown that the human lung is especially susceptible to ingested arsenic. After being consumed in drinking water, arsenic accumulates in the lungs. Lung cancer is now believed to be the most common cause of death from this widespread contaminant.;Most lung carcinogens, including tobacco smoke, asbestos, and silica, also cause non-malignant respiratory effects. Evidence suggests that arsenic in drinking water follows this pattern, but nearly all data involve adults with recent exposures. The impacts of early-life arsenic exposures on nonmalignant lung disease are largely unknown. In northern Chile, the city of Antofagasta (population 390,000 in 2014) had high concentrations of arsenic in drinking water (>800 mug/L) from 1958 until 1970, when a new treatment plant was installed. This scenario, with its large population, distinct period of high exposure, and accurate data on past exposure, is virtually unprecedented in environmental epidemiology. Chapter 2 of this dissertation describes a pilot study on early-life arsenic exposure and long-term lung function. We recruited a convenience sample consisting primarily of nursing school employees in Antofagasta and Arica (population 160,000) a city with low drinking water arsenic. Lung function and respiratory symptoms in 32 adults exposed to >800 mug/L arsenic before age 10 were compared to 65 adults without high early-life exposure. Early-life arsenic exposure was associated with 11.5% lower forced expiratory volume in one second (FEV1) (p = 0.04), 12.2% lower forced vital capacity (FVC) (p = 0.04), and increased breathlessness (prevalence odds ratio = 5.94, 95% confidence interval 1.36--26.02). Exposure-response relationships between early-life arsenic concentration and adult FEV1 and FVC were also identified (p trend = 0.03). These results suggest that early-life exposure to arsenic in drinking water may have irreversible respiratory effects of a magnitude similar to smoking throughout adulthood. Given the small study size and non-random recruitment methods, further research is needed to confirm these findings.;The arsenic concentrations >800 mug/L in Chile can reveal previously unknown health outcomes, but they do not shed much light on what the drinking water standard should be. Arsenic is known to cause lung cancer at concentrations above about 200 mug/L. The effects of lower exposures are unknown. This uncertainty has created controversy over the 10 mug/L World Health Organization guideline and U.S. regulatory limit for public water supplies because arsenic is widespread in groundwater naturally and expensive to remove. In Chapter 3, I present the first lung cancer study in the largest U.S. populations with exposures between 50 and 100 mug/L. This was also the first U.S. lung cancer study with individual data on past drinking water arsenic concentrations. We enrolled 196 lung cancer cases and 359 controls, matched on age and sex, from western Nevada and Kings County, California in 2002--2005. After adjusting for age, sex, education, smoking and occupational exposures, odds ratios for arsenic concentrations ?85 ?g/L (median = 110 ?g/L, mean = 173 ?g/L, maximum = 1,460 ?g/L) more than 40 years before enrollment were 1.39 (95% CI = 0.55--3.53) in all subjects and 1.61 (95% CI = 0.59--4.38) in smokers. Although odds ratios were greater than 1.0, these increases may have been due to chance given the small number of subjects exposed more than 40 years before enrollment. The findings suggest that concentrations near 100 ?g/L are not associated with markedly high relative risks. (Abstract shortened by UMI.).