A Meta-analysis of Arsenic Exposure and Lung Function: Is There Evidence of Restrictive or Obstructive Lung Disease?

Purpose of ReviewHundreds of millions of people worldwide are exposed to arsenic via contaminated water. The goal of this study was to identify whether arsenic-associated lung function deficits resemble obstructive- or restrictive-like lung disease, in order to help illuminate a mechanistic pathway and identify at-risk populations.Recent FindingsWe recently published a qualitative systematic review outlining the body of research on arsenic and non-malignant respiratory outcomes. Evidence from several populations, at different life stages, and at different levels of exposure showed consistent associations of arsenic exposure with chronic lung disease mortality, respiratory symptoms, and lower lung function levels. The published review, however, only conducted a broad qualitative description of the published studies without considering specific spirometry patterns, without conducting a meta-analysis, and without evaluating the dose-response relationship.SummaryWe searched PubMed and Embase for studies on environmental arsenic exposure and lung function. We performed a meta-analysis using inverse-variance-weighted random effects models to summarize adjusted effect estimates for arsenic and forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio. Across nine studies, median water arsenic levels ranged from 23 to 860 mu g/L. The pooled estimated mean difference (MD) comparing the highest category of arsenic exposure (ranging from >11 to >800 mu g/L) versus the lowest (ranging from <10 to <100 mu g/L) for each study for FEV1 was - 42 mL (95% confidence interval (CI) -70, -16) and for FVC was - 50 mL (95% CI -63, -37). Three studies reported effect estimates for FEV1/FVC, for which there was no evidence of an association; the pooled estimated MD was 0.01 (95% CI -0.005, 0.024). This review supports that arsenic is associated with restrictive impairments based on inverse associations between arsenic and FEV1 and FVC, but not with FEV1/FVC. Future studies should confirm whether low-level arsenic exposure is a restrictive lung disease risk factor in order to identify at-risk populations in the USA.