Open wide, and say "Aitch gee."
As in HG — chemical shorthand for mercury — the silvery liquid metal that's mixed with silver in countless dental fillings in Springfield each year.
What goes into fillings might not be a big worry during a visit to the dentist, but members of the Greater Springfield Dental Association are being asked to capture even tiny amounts of mercury that can go down drains and eventually land in Springfield's sewage treatment plants.
Most of that escaped mercury ends up in sewage sludge, but some reaches Wilson's Creek and the Little Sac River, contributing to mercury that can contaminate fish.
The voluntary effort, intended to lower mercury levels in effluent, is a benchmark for introducing the program to other parts of the country.
Springfield is the ideal location to measure the program's effectiveness, said Dr. Fred Eichmiller as Springfield Public Works laboratory analyst Stephanie Gott and chemist Karyn Highfill filled bottles with water flowing from the Southwest Waste Water Treatment Plant.
Measuring mercury here is easy, Eichmiller said: Contamination isn't a big problem, Springfield doesn't mix sewage and storm water and local dentists seem interested in taking part in the program.
Eichmiller, research center director for the American Dental Association Foundation, said detection of mercury is a fine science that can spot the substance down to one-half part per trillion.
Gott and Highfill wore paper coveralls, gloves and masks, not because they were standing in water flowing from the treatment plant, but to make sure sample bottles protected by two plastic bags didn't get contaminated. Even the breath from someone with an amalgam filling in his or her mouth could affect the results.
"It's a very challenging procedure," he said.
Sampling at the south Springfield treatment plant and the Northwest Waste Water Treatment Plant and before sewage flows into the plants will provide baselines to determine whether best management practices he will teach to local dentists in April have an effect, Eichmiller said.
The ADA's position is that while dental mercury might be a small percentage of mercury in the environment, it's enough of a concern that dentists should voluntarily adopt best management practices instead of waiting for government intervention, he said.
Dentists don't need to do much in addition to what most do already, such as clean filters and suction lines in their equipment, he said.
Greater Springfield Dental Society President Dr. Tom Stone said he hopes the training sessions will draw a large percentage of the 100-plus dentists in the area.
"My goal is to have at least 80 dentists there for training," he said.
The effort is a partnering of local dentists, the Missouri Dental Association, the ADA, Springfield Public Works and the University of Missouri Outreach and Extension.
Nowadays, mercury-based fillings account for about one-third of all fillings, Eichmiller said.
Amalgam fillings — made from mercury and silver powder — have been around for more than 100 years, but the demand from patients that dental work be aesthetically pleasing has made other materials that resemble dental enamel increasingly popular, Stone said.
"I don't think it's used as much today as it was," he said of mercury.
But removing even small amounts of mercury from the environment helps, said Outreach and Extension waste management coordinator Marie Steinwachs.
Former director of the Springfield/Greene County Household Hazardous Waste Center, Steinwachs now works throughout the state to reduce hazardous waste, including various sources of mercury, ranging from removing mercury switches from junked cars to special handling for burned-out fluorescent lamps.
She spent three years setting up the dental mercury training program. Financing comes from $90,000 in grants from the U.S. Environmental Protection Agency, the ADA, the Missouri Dental Association and in-kind contributions from Public Works.
Although Public Works has a program to make sure local metal-working industries remove metals from sewage and tests sludge to make sure mercury levels are within permitted limits, the effort Steinwachs is coordinating should be useful, Public Works assistant director Bob Schaefer said.
"Obviously, we would support keeping any mercury out of the wastewater stream," he said.
