An Evaluation of Disposal of Mercurywaste in Dental Teaching Hospitals of Karachi

An Evaluation of Disposal of Mercurywaste in Dental Teaching Hospitals of Karachi
Kefi Iqbal1, BDS, MSc, PhD, Maria Asmat2, BDS, Naresh Kumar3

1 Department of Dental Material Sciences, Baqai Dental College.
2 Department of Dental Materials Sciences , Baqai Dental College.
3 Department of Science of Dental Materials, Liaquat University of Medical and Health Sciences, Sindh.
4 Department of Oral Pathology and Oral Medicine, Baqai Dental College.
5 Department of Operative Dentistry, Liaquat University of Medical and Health Sciences, Sindh.
6 Department of Oral Pathology and Oral Medicine, Baqai Dental College.
Correspondence: Kefi Iqbal

How to CITE:

Iqbal K, AsmatM, Kumar N, Mohsin F, Ali F, Hanif S.An Evaluation of Disposal of MercuryWaste In Dental TeachingHospitals ofKarachi. JPakDentAssoc. 2012: 21 (2): 108 – 111


To evaluate the procedure for disposing of amalgam waste in dental teaching hospitals in Karachi according toAmericanDentalAssociation (ADA) and International StandardOrganization Standards (ISO).


A questionnaire was sent to eleven teaching dental hospitals in Karachi regarding the dispensing procedure to control the waste amalgam and dental amalgam restorations performed and removed per month.


According to the result of our survey, none of the dental teaching hospital inKarachi followed the ADA and ISO standard to dispose and recycle the amalgam waste, only 9.9% claimed that they use chair side traps and install amalgamseparator at chair side.Majority of hospitals (70%) preferred to use the handmixing alloy/mercury ratio. Numbers of amalgam fillings performed and removed by ten dental hospitals per month were 600 and 400 respectively.


Our results showthe lack of proper amalgam waste management in all the dental hospital of Karachi surveyed




ercury (Hg) as amalgam has been used as a direct restorative material for more than 15 decades. Dentists and the dental personnel have been directly and indirectly exposed through Hg emissions from incinerators and Hg in waste water from the different sources which could be either from households or dental clinics. The release of amalgam particles into dental office wastewater or in solid waste is an important concern as these particles could then be released into the environment. These releases take part in the environmental pollution through direct wastewater, incineration, land-filling and sewage sludge incineration, although the release from dentistry is less than 1% of the totalmercury discharged annually into the environment as a result of mankind activities. Out of the 10 000 tons of mercury released by industry, approximately 300 tons were contributed by dentistry all over the world in 1973.

Accordingly, dental clinics are playing a major role in mercury discharge. If the manipulation of amalgam and its waste products are not strictly regulated, it could be responsible for environmental pollution as well as occupational exposure. Amercian Dental Association has given a guideline for managing amalgam wastage. The purpose of this questionnaire based study was to evaluate themercury disposal practices of eleven teaching dental hospitals ofKarachi.


A questionnaire was sent to eleven teaching dental hospitals in Karachi, (Dr. Ishrat-ul-ebad Khan Institute of Oral Health Science, Darul Sehat Medical Hospital, Jinnah Medical and Dental College, Liaqat National Hospital,Alvi DentalHospital,Aga KhanHospital,Baqai Medical University, Jinnah PostgraduateMedical Centre, Altamash Institute of Dental Medicine, PNS Shafa Hospital, Hamdard University). The questionnaire also covered the procedure to control the waste amalgam and dispensing formused by the hospital shown in Fig. 1. The study was cross sectional and eleven hospitals involved in dental teaching were included. The American Dental Association standard criteria were utilized for the determination of disposing of mercury/amalgam waste. The questionnaire used is shown in figure 01. The filled questionnaires were checked for errors and compared with ADA guidelines. MS excel 2007 was used for data analysis.


Among eleven dental hospitals, ten responded. The hand mixing dispensing method was used by majority (70%) whereas the encapsulated form was (20%) used by only 2 dental teaching hospitals, whereas 1 Hospital used both handmixed and encapsulated amalgum (Figure 2) .

A method for disposing of amalgam wastage and percentage of ISO standard procedure to control the amalgamwaste at chair side is shown in Table 1.

Methods used for disposing of amalgam waste were sink (18%), bin (64%) and photofixer solution (20%). The number of amalgam fillings performed and removed by ten dental hospitals per month were 600 and 400 respectively, shown in Figure 3.


For mercury hygiene protocol there need to be a proper layout of the dental clinics. Trituration methods, condensation, cleaning and instruments sterilization. The removal of amalgam restorations and amalgam waste storage are also amatter of concern. It is estimated that the average mercury filling contains approximately 1gm of mercury. According to our survey, dental hospitals on the average produces 40 grams of mercury permonth, or 480 grams per year. There are 32 registered dental hospitals in Pakistan and if we calculate the annual release ofmercury thatwould be around 15.36 kg per year and this release is only contributed by the removal of old fillings. This study emphasizes that 400 grams ofmercury is produced from the removal of old dental amalgam filling permonth by ten dental hospitals ofKarachi.

The large number of teaching hospital preferred to use the hand mixing dispensation because of the cost saving, which may increase the chances of handling error like improper mixing ratio which contain more mercury, manipulation error and inadequate handling of mixed dental amalgam. Therefore, we do not achieve the proper control of amalgam waste which can be overcome by the encapsulated dispensation. The procedure of ADA standard to control the amalgam waste is being followed by western countries whereas we are failing to meet the criteria of ISO standardizations. Environ’s (draft) study showed that 29.7 tons of mercury discharges into the wastewater system, only 0.4 ton of this mercury actually reaches surface waters in the United States annually and another study conducted inNewDelhi India, revealed that 51 kg of mercury was released amalgam waste each year fromhospital and dental clinic.


None of the dental teaching hospital in Karachi followed the ADA and ISO standard for disposing and recycling the amalgamwaste.


The proper method of performing the recycling methods should be followed by all dental teaching hospitals, as per data obtained,majority of themare failing to meet the criteria according to the guidelines, so large amount of mercury is released in waste water. Therefore, we need to highlight the propermethods for dispensing of amalgamwaste according toADAregulations.


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