Serum matrix metalloproteinase-9 in children exposed to arsenic from playground dust at elementary schools in Hermosillo, Sonora, Mexico

Abstract

Arsenic exposure in adults has been associated with increased serum matrix metalloproteinase-9 (MMP-9), a biomarker which is associated with chronic respiratory disease, lung inflammation, cardiovascular disease and cancer. The objective of this study was to evaluate the association between serum MMP-9 levels in children, and arsenic exposure to playground dust. This cross sectional study examined of 127 children from five elementary schools, in Hermosillo, Sonora, Mexico. Playground dust samples were collected for each school and urine and blood samples were obtained. Arsenic was analyzed in the dust using a portable X-ray fluorescence (XRF) analyzer and the daily arsenic dust ingestion dose (CDI) was estimated. Total urinary arsenic was determined by Inductively Coupled Plasma/Optical Emission Spectrometry (ICP/OES). Serum was analyzed for MMP-9 using ELISA. Linear regression and linear mixed effects regression were used to assess the relationships between serum MMP-9 and arsenic exposure (arsenic levels in playground dust, log CDI and log urinary arsenic). Arsenic concentration in dust was positively associated with serum MMP-9 levels in crude analyses and after adjustment (P<0.01), MMP-9 and CDI were positively associated only after adjustment (P<0.01), and no association was found between MMP-9 and urinary arsenic. Arsenic ingestion from contaminated playground dust is an important route for pediatric toxicity, demonstrated through an association with increased serum MMP-9 levels.