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

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, urinary arsenic, arsenic chronic daily intake (CDI) and arsenic exposure from playground dust. This cross-sectional study examined 127 children from five elementary schools, in Hermosillo, Sonora, Mexico. Arsenic was analyzed in the dust using a portable X-ray fluorescence (XRF) analyzer. Total urinary arsenic was determined by inductively coupled plasma/optical emission spectrometry. Serum was analyzed for MMP-9 using ELISA. Arsenic levels in playground dust averaged 16.9 ± 4.6 mg/kg. Urinary arsenic averaged 34.9 ± 17.1 µg/L. Arsenic concentration in playground 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. In conclusion, our study showed an association in children between serum MMP-9 levels and playground dust arsenic concentrations. Therefore, exposure to arsenic in dust where children spend significant time may manifest toxic effects.