## MAXIMIZING VOLUNTARY REDUCTIONS IN DENTAL
AMALGAM MERCURY Reduction in Mercury Discharges

EPA # E0000127

PI-98765101-0

Brief Summary Report, November 2007

Environmental Assistance Center Marie Steinwachs, Director 200 Engineering Building North

410 6 th 

### Street
Columbia MO 65211 (573) 882-5011
moeac@missouri.edu

SUMMARY OF FINDINGSThe use of voluntary best management practic es for dental amalgam in the study area

dental offices resulted in a measurable and significant reduction in mercury load to the influent wastewater of the treatment plants.



### PROJECT OVERVIEW

The purpose of the study was to determ ine whether significant reductions in mercury discharges from dental offices could be achieved through voluntary best management practices (BMPs). Funding was provided by the U.S. Environmental Protection Agency and the American De ntal Association (ADA). Springfield,

Missouri was selected for th e pilot study based on inte rest and commitment of staff resources from the Springfield P ublic Works Department and the Greater Springfield Dental Society (GSDS). Th e University of Missouri Extension’s Office of Waste Management (now Envi ronmental Assistance Center) provided

administration and coordina tion for the project.

Influent and effluent samples were collected at Springfield ’s two wastewater treatment plants on a bi-weekly basis for 16 months. This included four months of sampling prior to intervention in the form of training dental offices to implement amalgam waste best management practices (BMPs). Samples were collected by Springfield Sanitary Services chemists following EPA Method 1669 and anal yzed for total mercury using EPA Method

1631.

Intervention Intervention consisted of a 1⁄2-day training course provided to ar ea dentists on best management practices for dental amalgam. The eighty dentists and dent al office staff that attended represented 54 local dental offices and 11 dental offices from other parts of Missouri. Participants recei ved a DVD, wall poster with best management practices, a

brochure of other available resour ces, and articles including:

 Dental mercury hygiene recommendations

 ADA Guidelines on Amalgam Accumula tions in Dental Office Plumbing

 Summary of Recent Study of De ntal Amalgam in Wastewater

 Missouri Dept. of Natural Resources dete rmination of status and options for various types of dental waste

 List of amalgam recyclers

Those who completed the training course re ceived 4 continuing education credits from the Greater Springfield Dental Society (GSDS), and dentists that did not attend or send staff to the training course received information and trai ning materials via mail.

Questionnaire A questionnaire was distributed to Springfie ld dentists by the GSDS and Environmental Assistance Center in February 2006 to co llect baseline data on amalgam use andmanagement practices as reported by Springf ield area dentists. The questionnaire was adapted from a national survey of dental office practices conducted by the ADA. The questionnaire was sent to 123 dentists and ther e were 48 responses, or a 39% return rate.

A follow up survey to dentists was distribute d to 254 members of the Greater Springfield Dental Society (GSDS) in February 2007 to measure any changes in management practices after the education efforts as repor ted by area dentists. The response rate was 76 dental offices or 30%. A comparison w ith the results of the first questionnaire provided insight into changes in the practices of Springfield dentists that were likely the result of voluntary best management practices.

RESULTS OF WASTEWATER AND BIOSOLID ANALYSIS Dr. Fred Eichmiller, ADAF Paffenbarger Research Center

Biosolid

Concentration data was collated from anal ysis of dried biosolid mixed from both treatment plants. The results showed that ove rall levels were very low and there was no statistical difference in mercury levels of treated biosolid before and after the

intervention.

Influent wastewater Influent water was sampled using a grab samp le technique at each central plant collecting point and analyzed for mercury conc entrations using the 1631 method. The concentrations were converted to mass units of mg/day by multiplying the sample concentration by the average daily flow rate re corded at the treatment plant on the day of sampling

. The mass loading of wastewater influe nt for the NW plant with only a few

dental offices showed a 34% reduction in mercury after the BMP training, but this reduction did not reach statistic significance. A similar analysis done for influent wastewater entering the SW treatment plan t where the number of dental offices was approximately thirty times greater and this analysis showed a highly significant 96% reduction in the influent daily mass of me rcury after the introduction of BMPs.

Effluent wastewater Effluent water was sampled using a grab samp le taken at each plan t discharge point and analyzed for mercury concentrations. Sampling was done on the same days as the influent water sampling. The concentrations were again converted to mass units of mg/day by multiplying the sample concentration by the average daily flow rate recorded at the treatment plant on the day of sampling. The mean daily load of mercury in effluent

water showed no difference between before and after the BMP training intervention for either treatment plant.

Conclusions

• The practice of BMPs in the area dental offices resulted in a measurable and significant reduction in mercury load to th e influent wastewater of the treatment plants.• The practice of BMPs in the dental offices did not result in a measurable change in biosolid mercury levels.

• The practice of BMPs in dental offices di d not result in a measurable change in mercury load to effluent treatment water.RESULTS OF QUESTIONNAIRE

Environmental Assistance Cent er, University of Missouri

The comparison of responses on reported dent al amalgam management practices before

and after intervention showed indications that the BMP tr aining and education efforts may have succeeded in changing some behaviors.

Amalgam Use Dental amalgam use decreased 5% from the year before.

Amalgam Capsules All dentists using amalgam used pre-capsula ted amalgam. There was no increase after training in the percentage of dentists that reported using a variety of capsule sizes to minimize waste. A significant decrease in im proper disposal of capsules in regular waste was observed after the training and education, while a signifi cant increase occurred in dentists setting amalgam capsules asid e for pickup by an amalgam recycler.

Scrap Amalgam BMPs advocate the recycling of excess scrap amalgam. The collecti on and recycling of scrap increased significantly after BMP trai ning while the improper disposal decreased.

Medical Waste Medical waste incinerators are a leading s ource of mercury emissions. The BMPs advise dentists to avoid placing amal gam in containers with medica l waste. There was a slight increase in the amount of amalgam scrap bei ng disposed of as medical waste after the BMP training. This finding may indicate a need for additional education to dental office staff and a need for better labeling and in struction from medical waste management companies.

Chair-side Traps The BMPs recommend capturing and recycli ng amalgam wastes in chair-side traps. There was a reported increase in the use of chair-side traps from the year before and a significant decrease in the practice of dispos ing of trap contents with regular waste

Vacuum Pump Filters Most of the respondents reported using vacuum pump filters. Many dentists in the BMP training course were unaware that the filter and its contents could be recycled together, and that filters could be repl aced at a cost of about $6-$7. Th ere was an increase in pump filter users who reported placing filter contents in a container with medical waste, and a slight increase in placing filter contents in a container for pickup by an amalgam recycler. There was also a reported decrease in the pr actice of placing filter contents in with regular office waste

Extracted Teeth There was significant increase in dentists repor ting that they disinfected the teeth and set them aside for an amalgam recycler. .Amalgam Recycling Since last year, there were an increased number of dentists who reported using an amalgam recycler. More dentists reported that th eir recycler also picks up medical waste.

Nearly half of dentists who reported using an amalgam recycler said they pay less than $25 per month for the service. A smaller number of dentists who use an amalgam recycling service claim that the recycler pi cks up amalgam waste at their office, while more than one-third reported shipping via US mail, UPS, or other shipping service. A majority of dentists who recycle amalgam re ported that the recycl er provides packaging material, shipping labels and shipping manifests

Deterrents to Amalgam Recycling The majority of dentists reported that they were not prevented from recycling due to the inability to locate a recycler in their area, locate a recycler to pick up small quantities of dental amalgam waste, find a method for shippi ng waste, or by the cost of recycling amalgam.

Knowledge of BMPs The majority of dentists reported being familiar with the ADA’s Best Management Practices. In regards to staff training in BMPs, there was a large increase in dentists reporting that they had provided this training. There was also an overall increase in the understanding of best management practices after training.

Amalgam Separators The majority of responding dentists did not use amalgam separators. There was a slight increase over the study period in the number who did report using a separator. Amalgam separators are not required in Missouri or in Springfield so it was assumed that very few

would be in use.

Bulk Mercury The overwhelming majority of dentists reported having no bul k mercury on the premises.

Conclusions

• The education and training provided to area dental offices resulted in an overall

increase in the use and understanding of BMPs.

• There were significant increases in the recycling of used amalgam capsules and scrap amalgam, and corresponding decreases in the disposal of these wastes as regular trash.

• Amalgam recyclers are providing more serv ices to area dentists, including the recycling of lead foil, filters, and amalgam-containing teeth.

AcknowledgementsThe University of Missouri Environmental Assistance Center woul d like to acknowledge and thank the following people and organizatio ns for their support and participation in this project:

• Environmental Protection Agency, Region VII for funding

• American Dental Association for funding

• ADAF Paffenbarger Research Center, especi ally Dr. Fred Eichmiller, for assistance with all aspects of the project

• Springfield Public Works Department fo r carrying out aspects of the project, especially Jim Burks, Karyn Highfill, Ste phanie Gott, Ed Malter, Carrie Lamb, and

Barbara Lucks

• Greater Springfield Dental Society, especia lly Dr. Tom Stone, Dr. Kelly Barnett, Jean Harmison and the dentists of Springfield fo r their commitment to the environment

• Jessica Adams-Weber, intern with the Envi ronmental Assistance Center for assistance with the project.