Human activities have increased the concentration of mercury in the environment. Mercury is a toxic metal that occurs naturally in the earth’s crust, if emitted or released into the air, land or water it poses a serious risk to human health.
Experts estimate that 10 per cent of the emissions of mercury to the atmosphere are from natural emissions such as volcanic activity, weathering of rock, water body movement, forest fires, and biological processes.
Also, 30 per cent is generated by current human activity and 60 per cent is re-emissions (evaporation, etc.) of mercury already in the environment, mostly as a result of previous human activity (UNEP, 2013)
However the recognition that mercury in dentistry represents a global threat that needed to be tackled through cooperation at the international level, led to the Minamata Convention on Mercury, an international treaty designed to protect human health and the environment from anthropogenic emissions and releases of mercury and mercury compounds.
Mercury is recognized as a chemical of global concern due to its long-range transport in the atmosphere, persistence in the environment, ability to bio-accumulate in ecosystems and significant negative effect on human health and the environment.
A former dean, Faculty of Dental Services, University of Lagos, Prof Godwin Toyin Arotiba, said everyone is exposed to some degree of adverse health effects depending on the chemical form, concentration, duration and life stage.
He said residents are exposed to mercury during dental surgeries through dental amalgam. Dental amalgam is a mixture of silver alloy (silver, tin and copper and sometimes zinc, palladium or indium) with mercury.
While presenting a paper titled ‘Implementing the Phase Down of Mercury Dental Amalgam: The Road Map to Mercury Free Dentistry in Nigeria’, reports by experts showed that millions of dentists around the world routinely used dental amalgam as a filling material to repair decayed teeth.
Prof Arotiba said in many developing countries, including Nigeria, dental amalgam is the preferred dental restorative material by dental practitioners, because it is very strong, durable, cheap and easy to use. Therefore, there are tons of mercury in the mouths of Nigerians due to dental amalgam filling.
“When dental amalgam is used, mercury will be released to the air, water and land, and some of it will eventually be taken up in fish and other living things, including humans,” he said.
He however debunked the idea that dental mercury mostly goes into the mouth of the patient, and more or less stays there until a person dies.
“But a close examination of the mercury life-cycle shows that nearly 80 per cent of the dental mercury used every year goes into the solid (municipal or hazardous) waste and wastewater streams, he said.
Prof Arotiba deplored the problem of poor waste management infrastructure in developing countries as well as open burning of wastes. He added that dentistry mercury from crematorium and dental clinics gets into the atmosphere and some into solid waste and eventual into fish in the sea.
He said other ways by which people are directly exposed to mercury include hand-mixing of mercury and metal powders, drilling of old amalgam fillings, extraction of teeth with amalgam, solid waste disposal bins, slow release of mercury from fillings already in place, emissions from clinic, wastewater system and mercury passing through latex gloves.
Also speaking in Abuja at the stakeholders’ meeting on the ‘Development of a National Policy for the Phase Down of Dental Amalgam’, Mrs Oluwatoyin Olabanji of the Department of Pollution Control and Environmental Health, Ministry of Environment, said in 2009, UNEP Governing Council established an Intergovernmental Negotiating Committee (INC) to prepare a legally binding international agreement to protect human health and the environment from the adverse effects of mercury. She said the treaty was adopted on 10th October 2013 and currently, 128 countries have signed the convention and 94 others have ratified it, including Nigeria.
Nigeria became the 88th party to the convention on February 1, 2018, thus the convention becomes binding on the country on May 1, 2018.
The Global Mercury Assessment was carried out in 2002 and updated in 2013, and highlighted the adverse impacts of mercury on human health and the environment, mercury’s global reach and the serious challenges facing its continued use.
On the current state of dental clinic in Nigeria, the Executive Director, SRADev Nigeria, Dr. Leslie Adogame, who presented a report on the State of Amalgam Use and Mercury Levels in Dental Clinics in Nigeria, carried out in some selected dental clinics in Lagos, Ibadan and Abuja, said 12 private dental clinics were used for the study of which 50 per cent have high vapour mercury emission.
According to the findings of the study Abuja dental clinics have the highest emission from the restorative dentistry and waiting area of the clinic, adding that the emission from the surgery room is nine times above the safety limit, which is about 930 per cent increment.
He concluded that most dental clinics/hospitals and incinerators/medical waste treatment facilities in Nigeria essentially are very high risk environments for mercury vapour emissions and as such pose serious health risk to workers and the general population.
However, stakeholders urged the Federal Government to initiate a coordinated multi-sectoral approach for an effective phase down of the use of dental amalgam in Nigeria.
The stakeholders, in a communiqué at the end of their meeting, also called for the introduction and promotion of alternatives/transition to alternatives through subsidies as well as immediate update of dental school curricula and training of academic staff of dental schools.
They also said the initiation of a phased down work plan must include legislative review and development of guidelines, gathering baseline data and developing the national policy.
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