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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 9  |  Issue : 1  |  Page : 30-33

Knowledge and practices regarding mercury hygiene and amalgam waste disposal: A survey among general dental practitioners


1 Department of Conservative Dentistry and Endodontics, Rayat and Bahra Dental College and Hospital, Mohali, Punjab, India
2 Department of Oral Pathology, Rayat and Bahra Dental College and Hospital, Mohali, Punjab, India
3 Department of Prosthodontics, Rayat and Bahra Dental College and Hospital, Mohali, Punjab, India

Date of Web Publication6-Mar-2017

Correspondence Address:
Sarita Bhardwaj
Department of Conservative Dentistry, Rayat and Bahra Dental College and Hospital, Sahauran, Mohali, Punjab
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0976-4003.201638

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  Abstract 

Introduction: Amalgam, the most commonly used restorative material, is composed of nearly 50% mercury and 69% silver. It cannot be disposed along with biomedical waste (BMW) because mercury-contaminated waste cannot be incinerated or autoclaved. Objectives: To assess the knowledge and observance of proper mercury hygiene and amalgam waste management among general dental practitioners (GDPs). Materials and Methods: A confidential questionnaire containing 14 questions regarding handling and disposal of amalgam was randomly distributed to 175 GDPs in Chandigarh, Panchkula, and Mohali. A response rate of 78% was obtained, and results were statistically analyzed. Results: Out of total dentists surveyed, 71% were found to be using amalgam as restorative material, 63% were doing <5 amalgam restorations per week. Only 6.5% of dentists placed rubber dam during removal and replacement of amalgam restorations. Fifty-five percent of dentists used high-volume evacuation. Filter was used only by 6% dentists. For 98%, dentists' evacuation drained into regular drain. Eighty-six percent of dentists never used amalgamator. Only 31% of dentists stored leftover amalgam scrap in radiographic fixer. Fifty-one percent of dentists disposed the bottle of leftover amalgam scrap along with BMW. One hundred percent of dentists disposed amalgam-contaminated gloves and cotton along with BMW. Only 17% of GDPs periodically monitored mercury vapors in their dental operatories. Conclusion: There exists a significant lack of knowledge regarding mercury hygiene and amalgam waste disposal among GDPs. Guidelines on mercury management need to be strongly implemented to prevent contamination of environment by mercury.

Keywords: Amalgam, biomedical waste, mercury hygiene


How to cite this article:
Bhardwaj S, Bhardwaj A, Kalra T. Knowledge and practices regarding mercury hygiene and amalgam waste disposal: A survey among general dental practitioners. Indian J Dent Sci 2017;9:30-3

How to cite this URL:
Bhardwaj S, Bhardwaj A, Kalra T. Knowledge and practices regarding mercury hygiene and amalgam waste disposal: A survey among general dental practitioners. Indian J Dent Sci [serial online] 2017 [cited 2020 Oct 30];9:30-3. Available from: http://www.ijds.in/text.asp?2017/9/1/30/201638


  Introduction Top


Dental Amalgam, which is one of the most versatile restorative materials used in dentistry, constitutes about 75% of all restorative materials used by dentists. It is serving dentistry for more than 165 years. Its advantages are manifold such as low cost, reliable long-term performance in load-bearing areas, self-sealing ability, and low technique sensitivity.[1] The main disadvantage with dental amalgam is that it is nonesthetic, and one of the main areas of concern is related to amalgam waste disposal and mercury toxicity. This is because it is composed of nearly 50% mercury and 69% silver.[2] Although there is evidence of a decrease in its use in the world, it is still the most commonly used restorative material in developing countries. If we go to the history, amalgam has gone through so many ups and downs right from the time of its introduction. It was introduced to America by two Frenchmen, Crawcour brothers, in 1833, and by 1845, its use was declared to be malpractice by the American Society of Dental Surgeons. This was the beginning of first amalgam war.[3] The universal acceptance of amalgam as a restorative material resulted from investigations of Black in 1895, 1896, and 1908.[3] The second amalgam war was provoked in 1920 by Professor Alfred E Stock, a leading chemist whose own health was affected due to mercury exposure in the laboratory. He questioned the supposed safety of dental amalgam, which started the second amalgam war.[4] We are currently in the advanced stage of third amalgam war. The argument reopened in the late 1970 as modern methods of detecting the presence of trace amount of mercury were introduced. In 1980, Doctor Hal Huggins publicly condemned amalgam. Doctor Huggins, a practicing dentist in Colorado, was convinced that mercury released from amalgam was responsible for plethora of human diseases.[5] However, according to the National Institute of Health (NIH)-NIH Research and Food and Drug Administration, there was no basis for claims that amalgam was a significant health hazard.[6] Dodes in 2001 did an evidence-based analysis of data supporting and condemning the use of amalgam and concluded that evidence supporting the safety of amalgam restorations is compelling, and amalgam use is safe and effective.[7] However, mercury toxicity is a well-known fact, and if mercury from amalgam is not managed properly and amalgam waste if not disposed according to recommended guidelines, it can cause serious environmental effects. The purpose of this study was to assess the knowledge and observance of proper mercury hygiene and amalgam waste management among general dental practitioners (GDPs).


  Materials and Methods Top


A confidential questionnaire was formed of ten closed and four open-ended questions regarding handling and disposal of amalgam. These were distributed randomly to 175 private practitioners in Tricity, i.e. Chandigarh, Mohali, and Panchkula. Completed forms were collected in person as well as by post. A total of 137 forms were received, and response rate was found to be 78%.

The following questionnaire was distributed:




  Results Top


Ninety-two percent of clinics were air conditioned, and the filter was changed periodically for almost all. Seventy-one percent of private practitioners were doing amalgam restorations, and 63% were doing <5 amalgam restorations per week. Twenty-one percent were doing 5–10 amalgam restorations per week. Ten percent were doing 10–15 amalgam restorations per week. Six percent were doing 15 and more amalgam restorations per week. Twenty-nine percent of dentists were not doing amalgam restorations at all, which is a statistically significant (P < 0.0001) finding. Only 6.5% of dentists placed rubber dam during removal and replacement of amalgam restorations. Fifty-five percent of dentists used high-volume evacuation. Filter was used only by 6% dentists. A statistically significant number of GDPs were not found using traps/filter/separators (P < 0.0001). For 98%, practitioners' evacuation gets drained into regular drain. Eighty-six percent of dentists never used amalgamator with precapsule alloy. Mortar and pestle was used by 83% dentist for trituration. Fifty-one percent of dentists were not storing leftover amalgam scrap in empty bottle, or in bottle with water, or in bottle with radiographic fixer solution. Thirty-one percent of dentists were storing leftover amalgam scrap in a bottle with radiographic fixer solution. Thirteen percent were storing in a bottle with water. Twelve percent were storing in an empty bottle. Fifty-one percent of dentists disposed this bottle along with biomedical waste (BMW). One hundred percent of dentists disposed amalgam-contaminated cotton rolls and gloves with BMW (P < 0.001). Mercury vapors were not periodically checked by 83% dentists (P < 0.0001).


  Discussion Top


Amalgam is not used by all the dentists surveyed in this study. Twenty-nine percent of dentists were not doing amalgam restorations and those who were doing amalgam restorations, i.e., 71% among that majority, i.e., 62% were doing <5 restorations per week. This clearly shows that there is a decline in the use of amalgam restorations among GDPs. Max Healthcare Dental wing in Delhi is totally mercury free. Amalgam restorations are not done there. And also in Himalayan Institute Hospital Trust, amalgam restorations are not done.[8] This decline in the use of amalgam is because of two parameters. One is its nonesthetic property, and the other is its mercury-related issues. Mercury is a heavy metal of known toxicity, noted for inducing public health disasters in Minamata Bay, Japan, and in Iraq.[9],[10] It exists in several forms, inorganic mercury which includes metallic mercury, mercury vapor, mercuric salts, and organic mercury, which includes compounds, in which mercury is bonded to a structure containing carbon atoms. There is some interconversion in vivo between various forms of mercury. Inhaled elemental mercury vapor is easily absorbed through mucous membrane and the lungs and rapidly oxidized to other forms. Methylmercury is easily absorbed through the gut and deposits in many tissues. Mercury salts tend to be insoluble, relatively stable, and poorly absorbed. Human toxicity varies with the form of mercury, the dose, and the rate of exposure. The target organ for inhaled mercury is primarily the brain, mercuric salts chiefly damage the gut lining, and kidney while methylmercury is widely distributed throughout the body.[11] According to the World Health Organization, most human exposure to mercury is caused by outgassing of mercury from dental amalgam, ingestion of contaminated fish, or occupational exposure.[12] The followings are the primary pathways of mercury release into the environment in health-care facilities.[13]

  • By medical waste incinerators due to burning of medical waste mixed with waste containing mercury. In the present study, 100% of dentists were disposing amalgam-contaminated gloves and cotton rolls with BMW. Fifty-two percent of dentists were even disposing bottle of leftover amalgam scrap along with BMW that way causing serious threat to the environment
  • Landfilling of mercury-containing medical waste without any pretreatment
  • Release of mercury into wastewater stream
  • Spillage of mercury in working environment.


The most common route of mercury exposure is inhalation of vapor after a spill or accidental skin contact with mercury. Accidental spill can increase the level of mercury in air or wastewater. It can lodge in cracks, mix with dust, or go down drains. It can adhere to fabrics, shoe soles, watches, and jewelry and can be transported to other locations. It can enter groundwater and way into the food chain. Mercury is a potent neurotoxin, a global priority pollutant, and a persistent bioaccumulative. Exposure to mercury impacts the central and peripheral nervous system, and it can damage the brain, spinal cord, kidneys, eyes, and liver. Mercury easily crosses the placenta, passing from mother to unborn child, where it can effect neurological development of the fetus. The clinical symptoms of acute inhalation of high levels of mercury vapor include gastroenteritis, chills, nausea, malaise, chest pains, and shortness of breath, coughing, gingivitis, excessive salivation, anuria, uremia, nephritis, anorexia, ataxia, and diarrhea. Symptoms of chronic exposure are weakness, weight loss, gastrointestinal disturbances, a tremor that begins with the finger, eyelids, and lips and progresses to generalized trembling of the body and violent spasms of extremities, and behavioral and personality changes including increased excitability, memory loss, insomnia, and depression. There may be painful scaling of the skin of hands and feet, a condition called Pinks disease or acrodynia.[14] Sources of mercury vapor in dental office are spills, open storage of amalgam scrap, open storage of used capsule, trituration of amalgam, amalgamator aerosol, removal, placement, finishing and polishing of amalgam, amalgam waste on cotton rolls and gloves, heating of amalgam-contaminated instruments, mercury release from stored materials, amalgam and mercury in plumbing traps, mercury trapped in tiles, and carpeting and amalgam scrap container if left open.[15] Amalgam is managed as per Dental Mercury hygiene recommendations (DMHR) by American Dental Association (ADA) and Occupational Safety and Health Administration.[6],[16],[17] According to this, high-volume evacuation is used while removing or finishing amalgam and evacuation system should have traps or filter which are periodically cleaned. In this study, during replacement or removal of amalgam, only 6% of dentists used rubber dam which means not only office team but also patient is at a high risk for mercury toxicity. In this study, 55% of dentists used high-volume evacuation, and traps were used only by 6.5% dentists, and for 98%, dentists' evacuation gets drained into regular drain. This simply shows that local sewer system is getting contaminated by mercury which can cause serious health effects. Amalgam debris may include 70% large particles (>100 µm), 20% medium size particles (10–100 µm), and 10% fine particles (<10 µm). Large particles can be trapped with chair side filter.[5] Amalgam separators are used to trap these particles. The basic type of amalgam separation technologies is the sedimentation units which reduce the speed of the down flow of water with baffles or tanks to allow amalgam particles to settle. Centrifuge units spin water out to sides of the unit. These units offer good amalgam removal but cause some foaming. Ion exchange units use polymer to capture small particles. Other wastewater treatment technologies such as electrolysis and chemical additions have also been adopted for dental applications.[18] According to the DMHR, ADA precapsulated alloy should be used in amalgamator with completely closed arm. However, in this study, 86% of dentists never used amalgamator, and mortar and pestle was used for trituration. That means bulk mercury and alloy is used which puts them at high risk because mercury can spill and also ratio of mercury in alloy can increase. Amalgam leftover scrap should be stored in tightly closed container either dry or in radiographic fixer solution, which cannot be disposed along with BMW. It needs special disposal. Even amalgam-contaminated cotton rolls and gloves need special disposal; it cannot be disposed along with BMW because mercury-contaminated waste cannot be incinerated or autoclaved. If incinerated, mercury will volatilize and enter the atmosphere, and if autoclaved, the volatilized mercury will escape from the autoclave when the door is opened presenting an immediate health hazard to office staff. Dental operatory should be periodically checked for mercury vapor using dosimeters and mercury vapor analyzers. The current limit for mercury vapor is 50 micrograms per meter cube in any 8 h work shift over a 40 h work week.[5] In the present study, 83% of dentists were not checking mercury vapor periodically. Mercury waste in India is disposed as stipulated under the Hazardous Waste (Management, Handling and Transboundary Movement) HW (M, H and TM) Rules, 2008. Most commonly used option in India is Disposal through Hazardous Waste Treatment Storage and Disposal Facility (TSDF). Here, mercury waste is disposed in a secured landfill after ensuring pretreatment by stabilization technique meeting the criteria as suggested under Central Pollution Control Board guidelines. TSDF center working in Punjab is at Nimbua, Derabassi, with only secured landfill facility.[13]


  Conclusion Top


Results of the present survey have demonstrated that:

  • There is a significant lack of knowledge regarding mercury hygiene and amalgam waste disposal among GDPs
  • DMHRs are not being followed by GDPs
  • Amalgam use is getting declined among GDPs
  • There is an urgent need to develop a systematic amalgam waste management plan
  • The guidelines on mercury management need to be strongly implemented by the State Pollution Control Board to prevent contamination of environment by mercury.


Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

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[PUBMED]  Medknow Journal  
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Phillips RW. Skinner's Science of Dental Materials. 9th ed. India: WB Saunders; 1992. p. 303, 329.  Back to cited text no. 2
    
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Forrai J. History of amalgam in dentistry. J Rev Clin Pesq Odontol 2007;3:65-71.  Back to cited text no. 3
    
4.
Koral SM. The scientific cases against amalgam. Int Acad Oral Med Toxicol 2002;2005:1-22.  Back to cited text no. 4
    
5.
Roberson TM, Heymann HO, Swift EJ. Sturdevent's Art and Science of Operative Dentistry. 5th ed. USA: Mosby; 2011.  Back to cited text no. 5
    
6.
Effects and side effects of dental restorative materials. NIH Technology Assessment conference. Adv Dent Res 1992;6:1-144.  Back to cited text no. 6
    
7.
Dodes JE. The amalgam controversy. An evidence-based analysis. J Am Dent Assoc 2001;132:348-56.  Back to cited text no. 7
    
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Agarwal A. Moving Towards Mercury Free Health Care: Substituting Mercury Based Medical Devices in India. New Delhi: Toxics Link; 2009.  Back to cited text no. 8
    
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Harada M. Minamata disease: Methylmercury poisoning in Japan caused by environmental pollution. Crit Rev Toxicol 1995;25:1-24.  Back to cited text no. 9
    
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Skerfving SB, Copplestone JF. Poisoning caused by the consumption of organomercury-dressed seed in Iraq. Bull World Health Organ 1976;54:101-12.  Back to cited text no. 10
    
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Bernhoft RA. Mercury toxicity and treatment: A review of the literature. J Environ Public Health 2012;2012:460508.  Back to cited text no. 11
    
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World Health Organization. The International Programme on Chemical Safety. Environmental Health Criteria 118. Inorganic Mercury. Geneva. Switzerland: World Health Organization; 1991.  Back to cited text no. 12
    
13.
Environmentally Sound Management of Mercury waste generated from Health care facilities-Central Pollution Control Board. Available from www.cpcb.nic.in>Guidelines_for_ESM . [Last accessed on 2014 Jan 04].  Back to cited text no. 13
    
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Rajendran R, Sivapathasundharam B. Shafer's Textbook of Oral Pathology. 4th ed. India: Elsevier; 2009.  Back to cited text no. 14
    
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Kulkarni S, Tadakmadla SK, Jain K, Duraiswamy P. Mercury hygiene practice among practicing dentist and undergraduate dental students of India. Rev Clin Pesq Odontol 2008;4:19-26.  Back to cited text no. 15
    
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ADA Council on Scientific Affairs. Dental mercury hygiene recommendations. J Am Dent Assoc 2003;134:1498-9.  Back to cited text no. 16
    
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Dental mercury hygiene recommendations. ADA Council on Scientific Affairs. J Am Dent Assoc 1999;130:1125-6.  Back to cited text no. 17
    
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Naik R, Sureshchandra B, Hegde S, Damda A, Malik M. Best management practices for hazardous waste disposal. J Endod 2011;23:106-13.  Back to cited text no. 18
    



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