Mercury contamination of heavy metal collection containers

We investigated discordant urinary mercury testing results from 2 patients with potential mercury exposures. Two patients had mercury levels of 634 and > 1,000 micrograms/L respectively. Although repeat 24 h urine mercury levels were elevated, spot urines were negative. Investigation revealed that technical HCl with high mercury content had been added to the 24 h urine collection containers. Subsequently, 20 hospitals were contacted to determine their heavy metals testing procedure and to analyze the acid used for mercury. Most hospitals contacted used acid in the preparation of their urine heavy metal collection containers. Of 13 HCl samples tested, 5 had low levels of mercury and 1 had heavy mercury content. Acid added to heavy metal collection containers should be of high purity grade to avoid mercury contamination of samples.