INTRODUCTION:

A biological agent or infection that constitutes a hazard to human or the surrounding environment is called a biological hazard. There are at least 193 important biological agents that show infectious allergenic, toxic or carcinogenic activities in the working population. Toxic substances enter our body through absorption, ingestion, inhalation and injection. Absorption can take place through the skin or eyes causing burns, sores, ulcer and other infections. Dentists and dental patients may be exposed to variety of microorganisms via blood or oral or respiratory secretions¹ the microbes penetrate the body through a cut on the skin while performing either a medical procedure, or a dental procedure.

Received on 15.05.2015 Modified on 22.06.2015

Research J. Pharm. and Tech. 8(8): August, 2015; Page 1048-1050

DOI: 10.5958/0974-360X.2015.00179.1

CLASSIFICATION OF BIOHAZARDOUS MATERIALS USED IN DENTISTRY²:

Hazardous materials from dental offices may include:

1 Photo processing wastes - X-ray film, lead foils and shields, X-ray fixer, developer and cleaner.

2 Chemical sterilants wastes - also known as chemiclave solutions (or) disinfectants.

3 Line cleaner wastes

4 Universal wastes: batteries, fluorescent lamps, mercury thermometers, etc.

5 Amalgam capsules:

(i) Scrap (non-contact) amalgam.

(ii) Amalgam capsules (empty, leaking or unusable )

(iii) Contact amalgam (eg . Extracted teeth)

(iv) Amalgam pieces captured by vacuum pump filters and screens.

PHOTO PROCESSING WASTE:

Silver: A heavy metal which enters the body through disposal of dental waste. The radiographic waste contains silver. Less amount of waste is generated from dental offices and the concentration if silver in X-ray film ranges from 8g-12g/L ³. There is high level of silver in the X-ray films that are not developed and to avoid these it should be sent to proper X-ray disposal company, this can be avoided by using digital X-ray^4,5

Lead: the X-ray packets contain lead, leachable ions and lead aprons. High doses of lead intake lead to reproductive toxicity, neurotoxicity, carcinogenicity, hypertension, renal function, immunology, toxicokinetics, etc⁶. Use of X-ray machines in dental offices predispose dentists to suffer from ionizing radiation^7,8. Lead aprons, periodic maintenance of the X-ray machine and radiation level sensors deal with radiation dangers^8,9. The way to reduce the toxicity released by these methods and save people from the after effects caused by this is, primarily to avoid the usage of such things. e.g. use of digital X-rays compared to the conventional film, developer/fixer combination¹⁰.

CHEMICAL STERILANTS WASTE:

Workplace Hazardous Materials Information System (WHMIS) trains the staff those who need to work in such places. Dental waste has been demonstrated to contribute significantly to pollution of the environment if poorly treated¹¹ and that it can lead to cross-infection risks¹² such as deadly HIV and Hepatitis among others¹³. Chromium, cadmium etc are called heavy metals which are considered to be hazardous. Chromium causes respiratory damage, kidney failure while cadmium causes lung cancer, kidney damage¹⁴. Rubber dams, gloves, mask, headcaps are mandatory equipments for any dental procedure but the use of these materials releases few toxic gases like Chlorofluorocarbons, dioxin etc which causes neurological cancers, respiratory problems¹⁵. Dental waste do not generally contain food remains to any large extent, but more of plastics (Polyvinyl Chloride PVC, Polyethylene, (PE), polypropylene (PPE). Any untreated waste should be properly labelled and handled by a waste hauler^16.Contaminated sharps must be placed in a puncture-resistant rigid container and treated prior to disposal. One should not pour sterilants into a septic system as this may significantly disrupt the bacteria which normally breakdown wastes^17,18.

LINE CLEANERS:

Line cleaners generally contain alcohols and/or other hazardous materials. Products with such ingredients that go unused are considered hazardous waste and should be disposed properly.

Disposal - It is done by City-sponsored Very Small Quantity Generated Program.

UNIVERSAL WASTES:

Needles, scalpels, glass carpules, burs, acid etch tips, files, blades and other similar objects, Their waste management includes collection in a red or yellow puncture resistant container with a lid that cannot be removed¹⁸. Aerosols cause airborne infections because they can stay airborne and has the potential to cause respiratory passage diseases. The various instruments that can cause airborne diseases ultrasonic scaler, air polisher, air driven hand pieces etc^19-21. Autoclaving must be done to prevent contamination. Legnani. et. al made an assessment of the aerosol contamination resulting from dental Treatments. It was proved that during working hours the average air bacterial load increased over three times, and the air load levels were 1.5 times (aerobic bacteria) and 2 times (anaerobes) greater as compared to the initial load²².

AMALGAM WASTES:

Mercury is neurotoxic, nephrotoxic and bio accumulative element and one of the main source of it in dentistry is amalgam. It can get into the environment through waste water, scrap amalgam or vapors. Vaporous mercury waste management includes: (i) storing unused elemental mercury in a tightly sealed container, (ii) contacting a certified biomedical waste carrier (CWC) for recycling or disposal, (iii) using a “mercury spill kit” in case of a spill of mercury, (iv) reacting unused elemental mercury with silver alloy to form scrap amalgam, (v) not placing elemental mercury in the garbage and (vi) not washing elemental mercury down the drain. Humans are continuously exposed to mercury via food, air, water²³. During the placement and removal of dental amalgam restorations, a variety of waste products is generated: (i) elemental mercury vapour–released from dental amalgam alloy, (ii) dental amalgam scrap–the amalgam particles that have not come into contact with the patient, (iii) amalgam waste–the particles that have come into contact with patient secretions, (iv) amalgam sludge–the fine particles present in dental office wastewater, commonly trapped in chair-side traps and vacuum filters^24,25. Although amalgam separators in the certification process are required to remove at least 95% of incoming mercury in a standardized laboratory test, their efficiency in practical use has not been properly investigated mercurypoisoning²⁶ can be characterized by tumours of the face, arms or legs and may be associated with progressive, tremulous illegible hand writing with slurred speech²⁷.

CONCLUSION:

Sufficient knowledge and adequate information regarding occupational hazards and its prevention will contribute in providing quality care to patients without any doubt. The global literature focuses strictly on control of infections and appropriate management of potentially infected materials, owing to the high profile of dentistry regarding infection transmission.

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