- Thursday | 06 Feb, 2014
- Mahmood A. Khwaja, Maryam Shabbir Abbasi, Sehrish Jahangir, Fareeha Mehmood
- Working Papers
Mahmood A. Khwaja , Maryam S. Abbasi, Fareeha Mehmood, Sehrish Jahangir
Mercury has been used in dental amalgams for over 160 years. These contains approximately elementary mercury 50 %, silver 30% and 20% other metals such as tin, copper & Zinc (Hardy, James E 1998; SDPI, 2013), Dental amalgams are also called silver fillings and amalgam fillings and are widely done because it’s inexpensive, ease of use, best settling material and most importantly it is resin free which make it less allergic than composite fillings. In 2005, UNEP estimated that 362 tons of dental mercury are consumed annually worldwide.3 These fillings gave off mercury vapors and its amount depends upon cavity size, tooth characteristics, composition, age of amalgam, time taken for filling, the number of fillings, temperature of ingested food/drinking liquids and the activities like chewing & grinding of teeth (VACMP, 1998; BIO 2012).The daily intake of the vapors of mercury, from ambient air and dental fillings, through absorption into the bloodstream of adults is about 32ng Hg /2ngm-3 (of background air) in rural areas and about 160ng Hg/10ngm-3 (of background air) in urban areas. Estimated average absorbed concentrations of mercury vapors from dental fillings vary from 3,000 to 17,000ng Hg(Clarkson 1988; Skare and Engqvist1994). As mercury vapor, it is taken up via the lungs, and 80% of it is absorbed.
Mercury (Hg), the essential constituent of dental amalgam, is also known as quick silver, is a toxic substance of global concern. A persistent pollutant, Mercury is not limited to its source but it travels, on time thousands of kilometers away from the source. Scientific evidence, including UNEP Global Mercury report, establishes mercury as an extremely toxic substance, which is a major threat to wildlife, ecosystem and human health at a global scale (Arvidson, Arvidsson&, Johansson 1994). It is also a major threat to fish that constitutes an all-important nutritious component of human diet. Children are more at risk from mercury poisoning which affects their neurological development and brain. Mercury poisoning diminishes memory, attention, thinking and sight. Mercuric ion reacts immediately with intracellular molecules or structures (e.g., enzymes, glutathione, tubulin, ion channels, or transporters), inhibiting their activities and interfering with normal cellular function. Mercury vapors can cause damages to central nervous system, thyroid, kidneys, lungs, immune system, eyes, gums and skin. Neurological and behavioral disorders include tremors, insomnia, memory and vision problems, neuromuscular effects and headaches. Fetuses and young children are more vulnerable to the mercury vapors (Alex Kirby et al. 2012; Pamphlett & Coote 1998; Stortebecker 1989);
Mercury poses risks to environment and human health, especially the health of children. In September, 2012, IUCN World Conservation Congress (WCC-2012) adopted SDPI Motion (M-169) and called upon government representatives of Intergovernmental Negotiating Committee (INC) to support a legally binding treaty on Mercury with an objective to protect human health and the environment from hazardous and toxic Mercury (UNEP 2013). In January, 2013, 140 countries in Geneva adopted a ground-breaking, world’s first legally binding treaty on mercury, now called “Minamata Convention on Mercury,” limiting the use and emission of health-hazardous mercury. To-date, the convention has already been signed by 94 countries (Minamata 2013).
In the past, a number of studies at dental sites in many countries have been carried out and reported. Only very specific data reported in these studies (24 dental sites in 10 countries), regarding indoor mercury vapors levels has been included and discussed. The present paper also describes and discusses findings of some recent investigations on indoor mercury levels carried out at dental sites in five main cities of Pakistan and six other countries.