The Minamata Convention

Thousands of people in the fishing town of Minamata, Japan, were poisoned by mercury in the food chain.

The Minamata convention was held in Japan in 2013 and resulted in a global treaty designed to protect the environment from mercury pollution and reduce the risk to human health by limiting the trade and supply of mercury containing products.

The Minamata treaty was signed by 128 countries and came into force in August 2017. The legally binding restrictions below were introduced in the United Kingdom in 2018/19.

1st July 2018.

Dental amalgam must not be used for the treatment of:

• Deciduous teeth
• Children under 15 years
• Pregnant or breastfeeding women

1st January 2019.

• Dental amalgam should only be used in pre-dosed encapsulated form
• Dental surgeries must be equipped with an amalgam separator
• Separator efficiency must be at a level that retains at least 95% of amalgam particles
• Dentists must ensure that all dental amalgam waste is handled and collected by an authorised waste management company

1st July 2019

Treaty member countries must publish a national plan describing measures to phase down the use of amalgam, which may be paced according to domestic needs (with public health, prevention and development of effective and safe alternatives as key focus areas)

Exceptions

The new legislation includes the slightly confusing exception that amalgam may be used in the prohibited patient groups ‘where it is deemed strictly necessary by the dental practitioner based on the specific medical needs of the patient’. Supplemental guidance statements have been published to assist clinical decision making and are summarized below:

• Medical needs should be interpreted to include specific dental needs of the patient i.e. where there are medical or dental reasons to justify the choice in the best interests of the patient, the practitioner will retain the option to use dental amalgam
• The apparently arbitrary age limit of children under 15 years is intended to establish a cohort of patients who have no heritage of dental amalgam restorations and whose life-long management is based on preventive and minimally invasive techniques
• There are no indications for the use of dental amalgam in primary teeth

Justification

Where an individual clinician chooses to use dental amalgam in the best interests of the patient, the decision must be justified and communicated to the patient so that they can provide valid consent, which should be recorded along with the justification in the patient’s clinical record. Examples of exceptional circumstances include:

• Allergy or local adverse reaction to a component of resin composite or glass-ionomer materials
• When moisture control or patient cooperation is insufficient to allow the use of an alternative to dental amalgam, even as a medium-term restoration

Environment, not health

The Minamata memorial, representing water and mercury. The 108 balls on the deliberately sloping site give a visual sense of them rolling into the sea. The water drops from a stylised japanese shinmei torii - a gateway marking the entrance to a Shintō shrine.

In 2010 it was estimated that the European Union accounts for 20-30% of the global demand for mercury. Prior to the Minamata Convention and EU regulations, several European countries had already phased-down or phased-out the use of dental amalgam. For example, Sweden and Norway completely banned its use in 2009 and 2011 respectively and Finland, Denmark and the Netherlands have phased down amalgam usage to just 1-5% of restorations.

The British Dental Association emphasize that both the Minamata treaty and related EU and UK regulations are purely for environmental protection and do not reflect any concerns about adverse effects of amalgam on human health and that the phase down of amalgam should occur in recognition that:

• Dental amalgam is a safe, durable and cost-effective restorative material
• Further development and optimisation of alternative restorative materials is needed
• Greater focus is needed on the prevention of dental disease
• Currently available alternative restorative materials are not economically viable in many circumstances, particularly in developing countries
• Restrictions on the use of amalgam would damage the financial stability of health systems as well as impact on individual patients' ability to afford dental care
• Introducing general restrictions on the use of amalgam could lead to significant global public health problems