Chronic arsenic exposure and risk of infant mortality in two areas of Chile

Chronic arsenic exposure has been associated with a range of neurologic, va scular, dermatologic, and carcinogenic effects. However, limited research h as been directed at the association of arsenic exposure and human reproduct ive health outcomes. The principal aim of this study was to investigate the trends in infant mortality between two geographic locations in Chile: Anto fagasta, which has a well-documented history of arsenic exposure from natur ally contaminated water, and Valparaiso, a comparable low-exposure city. Th e arsenic concentration in Antofagasta's public drinking water supply rose substantially in 1958 with the introduction of a new water source, and rema ined elevated until 1970. We used a retrospective study design to examine t ime and location patterns in infant mortality between 1950 and 1996, using univariate statistics, graphical techniques, and Poisson regression analysi s. Results of the study document the general declines in late fetal and inf ant mortality over the study period in both locations. The data also indica te an elevation of the late fetal, neonatal, and postneonatal mortality rat es for Antofagasta, relative to Vaparaiso, for specific time periods, which generally coincide with tbe period of highest arsenic concentration in the drinking water of Antofagasta. Poisson regression analysis yielded an elev ated and significant association between arsenic exposure and late fetal mo rtality [rate ratio (RR) = 1.7; 95% confidence interval (CI), 1.5-1.9], neo natal mortality (RR = 1.53; CI, 1.4-1.7), and postneonatal mortality (RR = 1.26; CI, 1.2-1.3) after adjustment for location and calendar time. The fin dings from this investigation may support a role for arsenic exposure in in creasing the risk of late fetal and infant mortality.