When mercury is exposed to sulphate-reducing bacteria, it undergoes a chemical change and becomes methylmercury. Researchers at the University of Illinois at Chicago (UIC) and Urbana-Champaign (UIUC) say that mercury entering drain water from dental offices and clinics is a source of methylmercury in the environment.
Karl Rockne, associate professor of environmental engineering at UIC, and James Drummond, UIC professor of restorative dentistry, studied waste water samples from collection tanks serving a single-chair office and a 12-chair dental clinic in Chicago. The study results appeared in the journal Environmental Science & Technology.
"They [the researchers] measured total mercury and methylmercury in both settled and mixed water samples. They then used quantitative polymerase chain reaction to identify the methylating bacteria," explains an article on the journal site.
Methylmercury appeared to be produced partially, if not fully in the waste water, noted Rockne in a UIC press release. In other words, methymercury was being produced before elemental mercury particles got into sewers where sulphur-reducing bacteria thrive, he added.
"The finding raised the question whether the culprit bacteria were living in the mouths of dental patients. We don't have the answer," said Rockne in the UIC press release.
Follow-up research is necessary to further understand this issue, Rockne said.
"Amalgam separators are a good first step, but maybe something else is necessary downstream to prevent further methylation and prevent further soluble mercury from getting through the system," he said in the UIC release.
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