Dietary inorganic arsenic intake in the U.S. and relation to serum matrix metalloproteinase-9 at different threshold concentrations of tap water arsenic

摘要

Arsenic (As) exposure is associated with cancer, chronic lung disease and cardiovascular disease, yet the mechanisms involved in As toxicity are not clearly understood. Matrix metalloproteinase 9 (MMP-9) has also been linked to these diseases, and, in earlier studies, we observed: 1) MMP-9 alterations in cultured lung cells exposed to As, 2) a positive association between As in drinking water and increased serum MMP-9 in humans, and 3) that the majority of As exposure in US populations was from food. The objectives of the current study are to evaluate the effects of dietary components of inorganic As intake on serum MMP-9 in subjects with household tap water As concentrations above and below 10 ppb, 5 ppb and 3 ppb. In a cross-sectional study of 215 adult subjects living in Arizona communities, 24-hour dietary intake was analyzed for inorganic As using published residue data, and As in cooking and drinking water was estimated from multisource water samples and reported consumption data. In mixed model regression, the sum of total inorganic As intake was positively associated with serum MMP-9, with and without adjustment for covariates. In adjusted models, dietary protein was a positive predictor and dietary folate, Hispanic ethnicity and age were statistically significant negative predictors. When total inorganic As intake was deconstructed into its component sources-dietary, drinking water and cooking water-, none of the sources were significant predictors. In models stratified by household tap water As, total inorganic As intake was consistently associated with serum MMP-9 among subjects exposed to tap water As below 10 and 5 ppb, but not above. Inorganic As from food alone was significantly associated with serum MMP-9 only among subjects exposed to household tap water As ≤ 3 ppb. Even in the U.S. where the average tap water As is 2.4 ppb, total inorganic As intake from food and water may contribute to As-induced changes in biomarkers associated with disease.