Arsenic exposure assessment Municipal drinking water records used in previous studies (Ferreccio et al. 2000; Smith et al. 2006) were linked with each participant’s residential history to obtain age-specific find more estimates of arsenic exposure. The drinking water database included over 15,000 arsenic measurements in Antofagasta and 11 other cities in northern Chile between 1962 and 1990,
when concentrations transitioned from high to low. In initial analyses, high exposure in early life was defined as drinking water containing >800 μg/l arsenic before age 10. The unexposed group included mostly long-term residents of Arica. In our main analyses, the unexposed group also included eight subjects who either moved to Antofagasta (from lower exposure areas) after age 10 or who lived in Antofagasta see more but were over age 10 during the high exposure period. Sensitivity analyses were conducted to evaluate whether changing cut-offs defining “high exposure”
(e.g., 800, 200, or 50 μg/l) and “early-life” (e.g., in utero, 10, or 18 years old) had any impact on results. Exposure–response was assessed both by using early-life arsenic concentration as a continuous variable in models and by stratifying subjects into low, medium, and high exposure categories. Statistical methods We analyzed data using SAS 9.2 (SAS Institute Inc., Cary, NC). Student’s t-tests were used to compare the means of continuous variables. We conducted one-tailed tests of significance for pulmonary outcomes
because of the clear direction of a priori hypotheses regarding arsenic. Otherwise, two-tailed tests were used. Lung function mean residuals (observed Loperamide values minus age-, sex-, and height-predicted values) and percentages (observed values divided by predicted values) were calculated for subjects with and without high early-life arsenic exposure. Predicted values for northern Chile were not available, so we used those of Mexican Americans in NHANES III (Hankinson et al. 1999). These are within 3% of reference values obtained from the PLATINO study of 5 large Latin American cities (Perez-Padilla et al. 2006). The choice of reference was not critical because our purpose was to compare arsenic exposed and unexposed, for whom the same reference values were used. Both univariate and multivariate models were performed. We did not enter age, sex, or height in the multivariate models of lung function because “selleck inhibitor unadjusted” values were residuals and percentages of age-, sex-, and height-predicted values. Final linear models adjusted for ever regularly smoking and variables that were both (1) associated with pulmonary function in other studies and (2) different between the arsenic-exposed and arsenic-unexposed groups in this study (Table 1). These were entered dichotomously: childhood secondhand tobacco smoke (Moshammer et al. 2006); wood, charcoal, or kerosene fuel use in childhood home (Fullerton et al. 2008); occupational air pollution (Blanc et al.