Less dental mercury getting into wastewater

A hearing on the environmental effects of mercury from dental amalgam has found that dentists continue to be the largest polluters of mercury in wastewater, although clinics that have adopted best practices have reduced their contribution by half.

US dentists consume on average 30 tons of toxic mercury each year, and are the largest polluters of mercury in the US, Michael Bender, Director of the Mercury Policy Project, testified to a US Government Committee. A separate study shows dentists contribute 40% of the mercury found in wastewater (see related story).

However, a report released by the Mercury Policy Project shows that dental mercury pollution has been declining in recent years. Toronto’s 50% drop in wastewater mercury over the past year has come from the use of amalgam separators and employment of best practices in dental surgeries. The Project urges other clinics to do the same. “Based on conservative estimates, the costs for dental clinics in the US to operate amalgam separators would average approximately US$600 dollars per year,” said Bender.

There is no evidence that dental mercury is harmful to health. But waste mercury released into the environment can be metabolised in fish and marine organisms into a more toxic form, methyl mercury.

Data from the US Centre for Disease Control suggests that one in eight women of reproductive age in the US have blood mercury levels that pose a risk to the developing foetus. Both the US Food and Drug Administration and the UK Food Standards Agency recently warned pregnant women and children not to eat certain seafood due to high mercury (see related story).