Pediatric reference values for chromium and mercury in urine in the City of Buenos Aires and Greater Buenos Aires

Introduction. Due to the heavy industrialization of the Autonomous City of Buenos Aires and Greater Buenos Aires, the population may have become exposed to metals. To assess the level of exposure to chromium and mercury in children, it is critical to have local reference values (RVs). Our objective was to determine pediatric RVs for chromium and mercury in a single urine sample. Population and methods: Children who were not exposed to the studied contaminants and who attended the Department of Low Risk Conditions and the Daycare Center Office of Hospital de Pediatria S.A.M.I.C. "Prof. Dr. Juan P. Garrahan" were included. Urinary chromium (UCr), urinary mercury (UHg), and urinary creatinine were measured. The p95 and its corresponding 95 % confidence interval (CI) were estimated based on the RV concept proposed by the German Human Biomonitoring Commission. Results: The study included 160 patients. A total of 144 samples from children aged 1-17 years (median: 7 years) were collected. UCr was measured in 137 samples and UHg, in 129 samples. The median value of chromium was 0.54 mu g/g of creatinine (range, undetectable to 3.06), while that of mercury was 0.49 mu g/g of creatinine (range, undetectable to 7.57). Conclusions: The RVs for UCr were up to 1.5 mu g/L [1.2-2.8] and up to 2.2 mu g/g of creatinine [1.8-3.0], and for UHg, up to 2.5 mu g/L [1.8-4.8] and 3.2 mu g/g of creatinine [2.5-4.7].