The use of dental amalgam contributes to a substantial amount of mercury (Hg) in the environment. According to BIO Intelligence Service (2012), dental amalgam is one of the main remaining uses of mercury in the EU. The demand for dental amalgam was still high in 2010, when it accounted for, on average, 75 tonnes of Hg per year in the EU. Some 75% of the dental facilities in all EU Member States are equipped with amalgam separators, but estimates suggest that about 45 tonnes of Hg per year from dental practices within the EU ends up in clinic effluents. This presents risks to microbiological activity in soils, wildlife and human populations, and the integrity of ecosystems. There is a need for new techniques that reduce the mercury leaked to the environment from this source.
Adequate handling of dental amalgam waste is necessary to achieve goals within EU legislation. The Hg-rid-LIFE project aimed at reducing emissions of mercury, by demonstrating new and improved techniques for decontamination of amalgam and mercury in the pipe systems of Swedish dental clinics. In its first stage, the project aimed at collecting 100 kg Hg sludge in selected dental clinics by improving standards for sampling mercury concentration in water; testing innovative and more efficient technologies for decontamination of pipe systems; improving existing technology for reducing emissions of mercury from amalgam separators; and developing guidelines for mercury remediation in dental clinics. In the long-term, the projects approach has the potential to remove up to 50% of the mercury emissions from the dental clinics taking part in the pilot project.
The Hg-rid-LIFE project demonstrated new and improved techniques to reduce mercury (Hg) emissions at source in Swedish dental clinics. In 132 dental clinics, techniques were demonstrated for the decontamination of dental amalgam and the removal of mercury from pipe systems. As a result of the decontamination actions in these clinics, a total of 372.25 kg of mercury sludge and 21.15 kg of mercury was collected, exceeding the original targets of the project. The projects results provide the basis for a more effective method for mercury decontamination that is now ready for implementation throughout Europe.
To enable its methods to be widely disseminated, the project produced a web-based training tool in Swedish and translated into English, German, Spanish and French. Project actions also improved awareness and knowledge of existing installation techniques and maintenance routines for reducing emissions of mercury from amalgam separators, which will be of use for the whole EU. By improving standards for sampling mercury concentration in water, together with its draft guidelines for mercury, the project also provides valuable input for developing green procurement standards for decontamination actions for mercury within the EU.
The projects methods for decontamination, including filming and the use of chemicals and new methods in pipes with poor access or suboptimal pipe dimensions, will enable decontamination of suction pipes that are currently poorly cleaned or are considered too expensive to decontaminate. In general, there will be a large economic gain for the EU if sludge from water treatment plants no longer needs to be sent to landfill due to high mercury concentrations. A lower mercury content of dental effluents entering wastewater treatment plants will reduce the need for municipalities to invest in expensive mercury abatement devices in sewage sludge incineration plants. It may also enable sewage sludge to be used for agricultural purposes.
Adequate handling of dental amalgam waste is necessary to achieve several goals of EU legislation, especially relating to water quality and the handling of mercury as a priority hazardous substance. The Hg-rid-LIFE project therefore is in line with the Water Framework Directive and the Environmental Quality Standards Directive, as well as the Community Strategy Concerning Mercury, Mercury Discharges Directive, and the Mercury Directive.
The socio-economic analysis of the decontamination conducted within the project indicated a benefit-cost ratio of approximately 2. That is, the value of the estimated health and environmental benefits due to mercury decontamination are double that of the costs of decontamination. Since mercury-based dental amalgam was banned in Sweden in 2009, it is likely that socio-economic benefits will be greater in countries where mercury-based amalgam is still used and where pipe systems have never been decontaminated.
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).