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ABSTRACT: Dr. Anupama Neelakantan, Dr. Yavaneetha Reddy, Dr. Sunil Dhaded

Dental healthcare staff should be aware of the proper handling and the management of dental waste. A lot of biomedical waste (BMW) is generated in dental practices that can be harmful to the environment and to those who come in contact with the materials, if not dealt with appropriately. Because of lack of clear‑cut guidelines either from Dental Council of India or Government of India or Indian Dental Association (IDA) on disposal of dental wastes, this article is designed to explore and review on these issues and formulate a simplified scheme. To prevent the harmful effects on health and the environment it is required to follow proper segregation protocol. The simplifi ed system provided a good model to be followed in developing countries like India and improved understanding among dental practitioners and dental staff, due to its self-explanatory nature.

Keywords: Biomedical waste, Dental, Waste management

INTRODUCTION:

Science has made our daily lives easier & convenient with various inventions, discoveries & technological advancements over many centuries, a large number of which were in the field of medicine and dentistry. Although, they save a lot of clinicians time and effort , a large amount of healthcare wastes are produced as a result , which might pose a threat to the living beings and the environment as a whole. Therefore , proper management of bio medical waste is of prime importance. The World Health Organization describes the healthcare waste as discarded, untreated materials from healthcare activities, which have the potential of transmitting infectious agents to humans.1 According to the Bio-medical waste rules 1998 of India, Bio – Medical Waste is defined as “Any solid, fluid or liquid waste, including its container and any intermediate product, which is generated during the diagnosis, treatment or immunization of human beings or animals, in research pertaining thereto, or in the production or testing of biological and the animal waste from slaughter houses or any other like establishments.2 There are a number of dental wastes that, when disposed improperly, could prove hazardous to the environment as well as those who come in contact with the materials.

Hospital waste management has been brought into focus in India recently, particularly with the notifi cation of the Biomedical Waste (Management and Handling) rules, 1998, in which the rule makes it mandatory for the health care establishments to segregate, disinfect, and dispose of their waste in an eco-friendly manner.3 American Dental Association (ADA) and Center for Disease Control recommend that medical waste disposal must be carried out in accordance with regulations.4,5

CLASSIFICATION OF DENTAL WASTE: According To Nancy Godwin:[6]

  1. General waste (nonregulated)
  2. Contaminated waste:
    • Regulated and
    • Infectious waste
  3. Hazardous waste:
    • Regulated and
    • Toxic waste.
CATEGORIZATION OF WASTES:

Table 1: Categories of biomedical waste, their segregation and disposal

Schedule I: Categories of biomedical waste[7]

Option

                                              Waste category

Treatment and disposal

Category no. 1

Human anatomical waste (human tissues, organs, body parts)

Incineration*/deep burial†

Category no. 2

Animal waste (animal tissues, organs, body parts, carcasses, fluids, blood,
experimental animals, waste generated by veterinary hospitals, colleges, discharge from hospitals, animal houses)

Incineration*/deep burial†

Category no. 3

Microbiology and bio‑technology waste (wastes from laboratory cultures, stocks or specimens of micro‑organisms, live or attenuated vaccines, human and animal cell culture and infectious agents from research and industrial laboratories, wastes from production of biologicals, toxins, dishes and devices used for transfer of cultures)

Local autoclaving/ microwaving/ incineration*

Category no. 4

Waste sharps (needles, syringes, scalpels, blades, glass, etc., that may cause
puncture and cuts. This includes both used and unused sharps

Disinfection (chemical treatment ‡/ autoclaving/ microwaving and mutilation/shredding)

Category no. 5

Discarded medicines and cytotoxic drugs (wastes comprising of outdated,
contaminated and discarded medicines)

Incineration*/destruction and drugs disposal in secured landfills

Category no. 6

Solid waste‑Items contaminated with blood and body fluids including cotton,
dressings, plaster casts, linen, beddings, etc

Incineration*/autoclaving/microwaving

Category no. 7

Solid waste (wastes generated from disposable items other than the waste sharps such as tubings, catheters, intravenous sets etc)

Chemical treatment‡/autoclaving/
microwaving and mutilation/shredding§

Category no. 8

Liquid waste (waste generated from laboratory and washing, cleaning,
housekeeping and disinfecting activities)

Disinfection by chemical treatment‡ and discharge into drains

Category no. 9

Incineration ash (ash from incineration of any biomedical waste)

Disposal in municipal landfill

Category no. 10

Chemical waste (chemicals used in production of biologicals, chemicals used in
disinfection, as insecticides, etc.)

Chemical treatment‡ and discharge into drains for liquids and secured landfill for solids

*There will be no chemical pretreatment before incineration; Chlorinated plastics shall not be incinerated; †Deep burial shall be an option available only in towns with population less than five lakh (5,00,000) and in rural areas; ‡Chemical treatment using at least 1% hypochlorite solution or any other equivalent chemical reagent; It must be ensured that chemical treatment ensures disinfection; §Mutilation/shredding must be such so as to prevent unauthorized reuse

 

Schedule II: Color coding and type of container for disposal of biomedical wastes[7]

Color coding

Type of container

Waste category

Treatment options as per schedule I

Yellow

Plastic bag

Category 1, Category 2, Category 3, Category 6

Incineration/deep burial

Red

Disinfected container/plastic bag

Category 3, Category 6, Category 7

Autoclaving/microwaving/ chemical treatment

Blue/white
translucent

Plastic bag/puncture proof container

Category 4, Category 7

Autoclaving/microwaving/
chemical treatment and destruction/shredding

Black

Plastic bag

Category 5, Category 9, Category 10

Disposal in secured landfill

1. Color coding of waste categories with multiple treatment options as defined in schedule I; Shall be selected depending on treatment option chosen; which shall be as specified in schedule I; 2. Waste collection bags for waste types needing incineration shall not be made of chlorinated  plastics; 3. Categories 8 and 10 (liquid) do not require containers/bags; 4. Category 3 if disinfected locally need not be put in containers/bags


MERCURY CONTAINING WASTES:

 

Dental Amalgam particles are a source of mercury, which is known to be neurotoxic and nephrotoxic. Amalgam waste should be placed in “white rigid” receptacles with a mercury suppressant, and it should be sent to mercury recovery process prior to final disposal. 8 Mercury from dental amalgam can get into the environment through several ways as

(a) through waste water, amalgam that is rinsed down drain or escapes from poorly maintained chair side taps and vacuum pump filters

b) removal of old amalgam fillings & autoclaved mercury containing wastes( certain hazardous wastes are to be autoclaved before disposal) that release merury vapours,are an immediate health hazard to the dental office staff and the environment

(c) If amalgam scrap is discarded into ordinary trash, it will go to landfill.9

Mercury disposal and extracted amalgam materials by dental clinics is largely unregulated. It is often rinsed down the drain, usually to a municipal waste water system or septic systems or dental clinic, deposited it in biomedical waste containers destined for waste incineration or placed in trash disposed in a municipal waste landfill or incinerator.

  • Do not rinse amalgam containing traps, filters or containers in the sink.
  • Do not place amalgam, elemental mercury, broken or unusable amalgam capsules, extracted teeth with amalgam or Amalgam containing traps and filters with medical or regular solid waste.
  • Recycle or manage as hazardous waste, the above mentioned materials. Empty dental amalgam capsules containing no visible materials may be disposed of as a nonhazardous waste.
  • Collect and store dry dental amalgam waste in a designated, airtight container. Amalgam which is designated for recycling should be labeled “Scrap Dental Amalgam” with the name, address and phone number of your office and the date on which you first started collecting material in the container. In the past, dental amalgam scrap may have been kept under photographic fixer, water or other liquid. If you should encounter amalgam stored in this manner, do not under any circumstances decant the liquid down the drain.
  • Keep a log of your generation and disposal of scrap amalgam.
  • Check with your amalgam recycler for any additional requirements. Some recyclers do not accept contact amalgam (amalgam that has been in the patient’s mouth); others may require disinfecting the amalgam waste. Separate excess contact dental amalgam from gauze that is retrieved during restoration and place in an appropriate container.
  • Use chair side traps to capture dental amalgam.
  • Change or clean chair side traps frequently. Flush the vacuum system before changing the chair side trap.
  • Change vacuum pump filters and screens at least monthly or as directed by the manufacturer.
  • Check the trap under your sink for the presence of any amalgam containing waste.
  • Eliminate use of bulk elemental mercury and use only precapsulated dental amalgam for amalgam restorations.
  • Limit the amount of amalgam triturated to the closest amount necessary for the restoration, i.e. don’t mix two spills when one spill would suffice. Keep a variety of amalgam capsule sizes on hand to ensure almost all triturated amalgam is used.
  • Train staff to handle mercury containing material in its proper use and disposal.10
LEAD CONTAINING WASTES:

Lead Foil Packets

The lead foil inside each xray packet is a leachable toxin and can contaminate the soil and groundwater in landfill sites. The management can be done by collecting lead foil packets in a marked container, once container is full, contact a certified waste carrier for recycling and do not throw lead foil packets into the regular garbage.11.12

Lead Aprons:

Lead aprons should not be thrown into the regular garbage since the lead can contaminate soil and groundwater via the landfills. Contact a certified waste carrier to recycle or dispose of unwanted lead apron13,14

XRAY PROCESSING WASTES:10

Dental offices that house and operate standard radiography equipment must process the Xray films using photochemicals fixer, developer and equipment cleaner. Each of these chemical solutions is unique and requires special handling and disposal procedures.

SilverContaining Wastes
(Xray Photographic Fixer):

Silver from used fixer is a valuable resource that should be recycled. There are two basic management options for fixer:

(1) onsite treatment and disposal; or

(2) offsite treatment and disposal.

Whether treated onsite or offsite, fixer is easily and economically recyclable and recycling is the preferred method of management. Untreated fixer can not be discharged into the sewer. Silver rich photo processing waste waters that are not treated onsite or hauled offsite for silver recovery are subject to full regulation as hazardous wastes.

 


Onsite Treatment and Disposal

Silver recovery units are available to remove the silver from the fixer. When using a silver recovery unit, remember to:

  • Check the unit daily for leaks, spills and overflows.
  • Periodically check the flow rate of solution to the recovery system. Typically a lower flow rate and a longer retention time will maximize silver recovery.
  • If using an electrolytic unit, check the appearance of the silver plate. The plate should be tan to brown and grainy. If it is black, mushy and smells like sulfur, the amperage may be too high. If the silver plate is hard and white, the amperage is probably too low. Consult your user’s guide for specific guidance.
  • Test the silver concentration of the treated fixer monthly. The test can be performed with an analytical test kit or a lab analysis. Periodic testing will tell you how effective your unit is at capturing silver and will alert you to recovery unit problems.
  • Record test results in a silver recovery log.
Offsite Reclamation/Recycling

Used Xray fixer solutions can be hauled offsite for treatment and recycling to a EPA(environmental protection agency) licensed recycling facility. If the silver is reclaimed, the waste stream may qualify for exemption or reduction in generator and hauling requirements. For offsite recycling, the generator should collect and store the used fixer solution in a labeled closed plastic container. The label affixed to the container should indicate the contents "Silver containing Used Fixer To Be Recycled" and include the accumulation start date.

Xray Photographic Developer:

Do not mix used developer and fixer solutions. Waste developer may be flushed down the drain, as long as the pH of the solution does not exceed the pH standard of the local sanitation agency. Most developer solutions are slightly caustic in nature, i.e., they have a high pH. Caustic solutions with a pH greater than the local pH limit should not be discharged down the sanitary sewer. Contact the local sanitation agency for guidance on disposal procedures for the developer solution.

Xray System Cleaners Containing Chromium:

Cleaners used to clean the Xray developing systems may contain chromium. If possible, switch to a nonchromium containing cleaner which can be discharged in to the sanitary sewer. Otherwise, the waste must be handled as hazardous waste, requiring proper collection, labeling and disposal.

 

METHYL METHACRYLATE: 15

The liqiuid component of the acrylic used in dental procedures is methyl methacrylate(MME), which is an extremely inflammable. Waste or spilled liquid MME is a hazardous waste due to flammability characteristic and therefore must be disposed off as such. Any materials used to clean up a spill of liquid MME are also considered hazardous waste.

  • When liquid MME has been mixed with the powder component & polymerised into the acrylic , the acrylic does not exibit the flammability characteristic & is therefore not a hazardous waste. Waste acrylic can be discarded in the regular trash
  • Liquid MME has a strong pungent odour even at very low & safe exposure levels . The OSHA permissible limit for MME is 100 ppm ,( 8 hour TWA). Symptoms of exposure to high concentrations of MME vapors include eye irritation, headache , drowsiness, dizziness, difficulty in breathing & loss of consciousness. Liquid MME can cause considerable irritation or burns to the skin & eyes
CHEMICALS, DISINFECTANTS, AND STERILIZING AGENTS:

The dental office utilizes many chemicals, disinfectants, and sterilizing agents that may be hazardous to the environment if they are not properly disposed. Management can be done by ensuring that staff handling these materials are trained in Workplace Hazardous Materials Information System (WHMIS), Avoid the use of chemical sterilants whenever possible, Use steam or dry heat to sterilize your dental instruments, If using disposable plastic components, use non-chlorinated plastic (i.e. not PVC) to minimize environmental impacts, Rinse empty sterilant containers with water and place the empty containers in your solid waste stream, Avoid halogenated products (i.e. those with chlorine or iodine) since these can have detrimental effects on the environment, Do not pour ignitable substances (straight alcohols, ether, acetone, xylol, chloroform) or other solvents down the drain, Do not pour x-ray cleaning solutions containing chromium down the drain, Do not pour any used or unused chemicals down the drain that contain high concentrations of formaldehyde without contacting your municipality first, Do not pour sterilant solutions into a septic system. This may significantly disrupt the functioning of the system by killing the bacteria, which normally breakdown wastes, Don’t pour concentrated alcohols, ethers or peroxides down the drain. These materials are flammable and could start a fire or explode13,16.

GYPSUM CONTAINING WASTE:

Though gypsum containing wastes are non infectious as they are devoid of human fluid contamination, they are considered potentially toxic to the environment. In accordance with the Environment Permitting (England and Wales) Regulations 2010, gypsum was banned from normal landfill (containing biodegradable waste) and must go into a separate cell for high sulphate waste. Dental study moulds contain gypsum and plaster cast which, when landfilled with biodegradable waste, can produce hydrogen sulphide gas. Hydrogen sulphide gas is highly toxic and malodorous. The majority of dental study moulds are not infectious but should be segregated as a specific gypsum waste stream and be disposed of at specialist landfill sites.17

MEDICAL WASTE:

Regulated medical waste consists of sharps (hypodermic needleds, blades, syringes) and biohazardous wastes (e.g. laboratory wastes, solid wastes covered with blood or other potentially infectious materials and pharmaceuticals). Wastes containing mercury or contaminated with mercury should never be placed with the medical wastes as these wastes will be incinerated and there by releasing mercury into the environment.

Waste Sharps:

Sharps containers are designed specifically for the containment and disposal of sharps such as needles, syringes with needles, scalpel blades, clinical glass or other items capable of causing cuts or punctures. Sharps are to be placed into a puncture resistant leakproof container designed specifically for the management of sharps. If these containers are not resistant to penetration or compression, they pose a health risk to those involved in their handling and disposal.

Needlestick and puncture wound injuries and resulting infections have been recorded in situations where sharps have been improperly handled and/or disposed. All clinical sharps should be considered potentially infectious. Disposable sharps should be placed in a proper sharps container. A sharps container should be located in each operatory and the sterilization lab.

These should be: Separated from other types of biomedical waste. Placed in a rigid, puncture resistant, leakproof container (provided by biomedical waste disposal vendors) and labelled“biohazard waste sharps” .

Permanently sealed in the container (when full) and picked up by a biomedical waste disposal vendor for proper disposal. To prevent injury do not fill sharps containers past the fill line or if no fill line exists, more than three quarters.

Other types of biomedical waste including soiled rubber gloves, used swabs and other blood or body fluid saturated items. These should be Separated from waste sharps. Placed in a red bag that is labeled “biohazard” . Stored in a rigid leakproof container. Picked up by a biomedical waste disposal vendor for proper disposal.

Waste sharps and other types of biomedical waste must not be mixed with or disposed of as municipal garbage.10

NONHAZARDOUS WASTES:

Paper, Cardboard, Aluminum, Plastics, etc. It should be minimized by using responsible suppliers, Office paper should have a high-recycled content, Minimize plastic waste by using refillable bottles for disinfecting or cleaning products and reusable devices for dental procedures where feasible, Avoid containers or packaging made of PVC plastic where feasible. This material is difficult to recycle and can produce acid gases if incinerated as part of your municipal waste treatment, Paper waste, cardboard and plastic containers (clean or rinsed) should be recycled where this service exists 18.

POLLUTION PREVENTION POLICIES:

We cannot afford to be negligent or ignorant towards the environment. It is essential that we follow norms and regulations in the dental clinic to ensure minimal damage to the environment. Control strategies must be implemented to reduce the generation of waste and minimize the potentially detrimental effect on employee safety and the environment, based on the following principles:

  • Avoid, eliminate or substitute polluting products or materials.
  • Reduce use of pollouting products or materials.
  • Elimination and reducte of the generation of polluting byproducts.
  • Reuse and recycle polluting byproducts.
  • Energy recovery from polluting byproducts.
  • Treatment or containment of polluting residual byproducts.
  • Remediation of contaminated sites.10
CONCLUSION:

In developing Countries like india, the proper disposal of infectious waste is a growing problem and if it is not managed in a sustained way, it will make the situation worse. There is considerable variation in the knowledge, facilities, handling and disposal of BMW among dental practitioners and dental office personnel and dental students There is an urgent need to update the curriculum, regular orientation training programs and strict implementation of guidelines for BMW management & upgrade the disposal facilities at independent dental laboratories, private dental clinics & dental educational institutions to correct the deficient practices. The monitoring agencies needs to supervise the strict implementation of BMW regulations at private sector establishments.

REFERENCES:
  1. World Health Organization. Safe health-care waste management, Available from: www.who.int/water_sanitation_health/medicalwaste/ en/hcwmpolicye.pdf2004 [
  2. Sharma M (2002): Hospital waste management and its monitoring, (1 st ed.), Jaypee Brothers Medical Publication.
  3. National Guidelines on Hospital Waste Management. Biomedical Waste Regulations; 1998.
  4. Harrison B, Nicosia J. States act to regulate medical waste. J Am Dent Assoc 1991;122:118-20.
  5. Parkash H, Kohli A, Chaudhary S, Hallikeri K. Biomedical and dental waste management: An essential component of asepsis in dental clinics. Dentistry India; 2011. BIO waste-scribed. Available from: http://www. scribd.com/doc/63117257/Bio-waste.
  6. Goodwin N. Lab procedures and waste management module-8. Available from: http://www.sngoodwintraining.com/resources/Lab+Procedures+and+Waste+Management.ppt.
  7. Notification by the Ministry of Environment and Forests, Govt. Of India, New Delhi, 20th July, 1998. Available from: http://www.envfor.nic.in/legis/hsm/biomed.html.
  8. Waste segregation and national colour coding approach. Available from: http://www.defra.gov.uk/environment/waste/special/index.html.
  9. Thota MM, Bathala LR, Theruru K, Shaik S, Jupidi B, Rayapati S. " There's plenty of room at the bottom": The biomedical waste management in dentistry. Journal of Dr. NTR University of Health Sciences. 2014 Jul 1;3(3):149.
  10. http://www.ida.org.in/BiomedicalWasteProtocol/DPS_classificationtypesofwaste.htm
  11. Fan PL, Bindslev DA, Schmalz G, Halbach S, Berendsen H. Environmental issues in dentistry - mercury. Int Dental J 1997;47:105-09.
  12. Available from: http./ /www.cdphe.state. co.us/hw/photo pdf. for more information.
  13. Available from: http://www3.uwm.edu/ dept/shwer/publication/cabinet/pdk/ guidefordentist.pdf
  14. Available from: http://www.p2pays.org ret/01/00020htm for more information
  15. https://www.nyu.edu/life/safety-health-wellness/be-safe/environmental-health-and-safety/waste-disposal/dental-clinic-wastes.html
  16. Wentz Charles A. Hazardos Waste Management, McGraw hill international editions,Chemical Engineering Series, McGraw Hill Inc. 2ed Singapore, 1995:80- 351
  17. www.initial.co.uk › Healthcare Waste › Dental Waste.
  18. Laboratory diagnosis, biosafety and quality control. National institute of communicable diseases and national AIDS control organization, Delhi, 26-41.

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