Objective: To determine the prevalence of elevated urinary mercury (Hg), as a marker of exposure, in a population of children drawn from an inner-city community with documented access to elemental mercury.
Methods: A prospective consecutive patient series was conducted from November 1998 to January 1999 at an inner-city clinic in New York. Anonymous urine specimens from subjects (aged 1-18 years) were collected in mercury-free containers, split, acidified with 1:100 hydrochloric acid, and frozen. Cold-vapor atomic absorption spectrofluorometric assays were conducted simultaneously at laboratories at the University of Washington and the New York City Department of Health.
Results: We enrolled 100 children (mean age 9.4 years; 62% male; 55% Hispanic; and 43% African American). Assay results from both laboratories were strongly correlated (r = 0.8, P <.0001). Mean urinary Hg was 1.08 +/- 1.82 microg/L. The 95th percentile for urinary Hg was 2.8 microg/L (range 0.2 to 11.7 microg/L). Five subjects had Hg levels above 5 microg/L.
Conclusion: We found that 5% of subjects had unsuspected elevated urinary Hg levels. This finding, in a group of inner-city minority children, strongly supports the need for further investigation of the sources of mercury exposure in this population.