Mercury is a persistent, bio-accumulative toxin, risky to human health, wildlife and the environment. While there has been considerable public debate about the potential health effects of mercury fillings, little attention has been focused so far on the disposal of waste dental mercury. Mercury is a natural metallic element. Human activities--including the use of dental fillings contribute around 70% waste. Levels of mercury in the enviornment have increased dramatically, with a twenty fold increase over the past 270 years.
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.
Disposable amalgam traps are preferable to reusable traps because of the difficulty in removing amalgam particles from the trap without discharging them in to the sewer or garbage. Disposable traps should be changed weekly or more frequently if needed or as recommended by the manufacturer of your equipment.
Only traps on chairs used for amalgam placement or removal need special handling. Traps from chairs not used for amalgam procedures may be placed in the regular solid waste.
The use of reusable chair-side amalgam traps is not recommended. However, if reusable amalgam traps are used, please follow the following steps:
Contact amalgam is amalgam that has been in contact with the patient. Examples are extracted teeth with amalgam restorations, carving scrap collected at chair-side and amalgam captured by chair- side traps, filters or screens. Many scrap amalgam recyclers accept teeth with amalgam as long as the sender certifies that they are not infectious wastes. Extracted teeth without attached tissue are considered non-medical wastes, unless the extracted teeth are deemed as biohazardous by the attending surgeon or dentist. However, extracted teeth with amalgam should be managed as hazardous waste or recycled.
To dispose of contact amalgam, dentists can choose to either collect or store it as hazardous waste or collect and store as recyclable waste, if the metal recycler accepts contact amalgam.
In addition to dental amalgam, other sources of heavy metals in the dental clinic should be recycled/reclaimed as much as possible. The most common source of regulated heavy metals in the office is lead from lead foil and lead shields. Lead cannot be placed in the regular solid waste containers nor can it be disposed of down the drain; it must be managed as either recyclable metal or hazardous waste.
Other metal sources include nickel and chromium from stainless steel orthodontic wires and crowns, and beryllium and nickel from crowns. These materials should not be discharged into the sanitary sewer system. X-ray photochemicals also contain heavy metals. Elemental nickel, chromium in stainless steel (does not include X-ray cleaning solutions) and other heavy metals should be recycled as scrap metal. As long as it is not fine powder, elemental metals other than lead or mercury can be disposed of as solid waste. Impression materials containing zinc oxide could be considered hazardous waste.
Dental offices that house and operate standard radiography equipment must process the X-ray films using photochemicals - fixer, developer and equipment cleaner. Each of these chemical solutions is unique and requires special handling and disposal procedures.
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 wastewaters that are not treated onsite or hauled offsite for silver-recovery are subject to full regulation as hazardous wastes.
Silver recovery units are available to remove the silver from the fixer. When using a silver recovery unit, remember to:
Used X-ray 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.
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.
Cleaners used to clean the X-ray developing systems may contain chromium. If possible, switch to a non-chromium 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.
The dental community uses a variety of chemicals for sterilizing, disinfecting and cleaning. Several of these products may contain active chemical ingredients (e.g. formaldehyde), that may be classified as hazardous. In addition, many municipalities place concentration limits on chemicals released to the sewer. Before discharging chemicals into the sewage system, consult the municipality for further information.
Some of these chemicals may be explosive if released into the sewers in large quantities. Other chemicals may disrupt the microbial process that breaks down wastes in sewage or damage the drainage and sewer pipes over time. Additionally, certain chemicals may negatively impact the environment and human health. Using less harmful alternatives, cleaning methods and/or surface barriers can reduce the impact on the environment and the need for special handling of waste in the dental practice.
If classified as special waste, used cleaning or disinfectant solutions should be stored in labeled, sealed and leak-proof containers in a secure location. This would minimize an accidental spill or leak and container failure will not result in the chemicals entering any sanitary sewer, septic system or storm drain. If this is not possible then, adequately sized secondary containment should be provided for this equipment or all floor drains in the area should be capped. Hazardous waste disposal vendors can provide pick-up services for special wastes or flammable wastes. If not classified as special waste, small quantities of cleaning solutions and disinfectants may be discharged to sanitary sewers (but not into storm sewers or septic systems).
If any chemical has a pH less than or equal to 6.0 or greater than or equal to 10.5, contact the municipality for disposal guidance. If any chemical contains formaldehyde and/or formalin, gluteraldehyde, ammonia or phenols, contact municipality for disposal guidance.
If any detergent contains nonyl phenol ethoxylates, determined to be toxic substances contact the municipality for disposal guidance. Discard pharmaceutical wastes such as unused drugs and narcotics through an approved waste carrier. Before discharging chemicals, disinfectants and sterilizing agents into the sewer ensure that guidelines are followed.
Thoroughly rinse empty disinfectant containers and recycle or dispose of them in regular garbage. Collect and transport chemicals, disinfectants or sterilizing agents in an appropriately labeled, sealed container to a dental clinic for disposal through an approved waste carrier.
Do not pour ignitable/flammable substances (straight alcohols, ethers, acetone, xylol, chloroform) or other solvents down the drain. Do not pour X-ray cleaning solutions containing chromium down the drain. Hexavalent chromium compounds are deemed toxic. Furthermore, this is classified as hazardous waste.
For portable dental equipment and mobile dental units, do not dispose of any accumulated chemicals, disinfectants or sterilizing agents in a remote site which does not have a disposal arrangement through an approved waste carrier.
If the dental practice is connected to a septic system, do not discharge sterilants or disinfectants (like bleach and ammonia based cleansers), chemical solvents and pharmaceuticals. These may disrupt the proper functioning of the septic system. Use alternatives or collect discharge for pickup by an approved waste carrier. Consult the municipality for further guidance.
Gluteraldehyde and orthophthaldehyde (OPA) are the active ingredients is several brands of sterilizing solutions. The sole active chemical of the neutralizing solution is glycine.
To dispose of waste glutaraldehyde or OPA down the sanitary sewer drain
Gluteraldehyde degrades after activation and most likely will become non-hazardous within the allowed hazardous waste accumulation time (90-180 days). Generators of waste glutaraldehyde, who claim that it has degraded to non-hazardous levels should check with their suppliers to see if they have data to support their claim. If the data is not available, then generators will have to produce their own supporting data to make the determination or either neutralize the solutions with glycine or handle it as hazardous wastes. This does not apply to OPA solutions.
Formalin is commonly used as a tissue preservative. Formalin is a generic mixture containing formaldehyde; it may also contain methanol and other chemicals. Harvey's Vaposteril solution also contains small levels of formaldehyde as an active ingredient.
To dispose waste formalin into the sewer the following requirements must be met:
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.
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 leak- proof 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:
Other types of biomedical waste including soiled rubber gloves, used swabs and other blood or body fluid-saturated items. These should be
Waste sharps and other types of biomedical waste must not be mixed with or disposed of as municipal garbage.
Solid 'red-bag' waste must be collected and disposed as regulated medical waste. You must contact a registered medical waste hauler for transfer of solid waste to a licensed offsite treatment facility. Proper treatment by a permitted facility consists of either autoclave sterilization or incineration.
Human tissue waste generation is normally limited to oral surgeons and periodontists. In this context, all human tissue wastes are required to be treated as biomedical/pathological wastes.
Separate human tissue from sharps and blood soaked materials. Collect human tissue in red liners that are marked with the universal biohazard symbol (these liners are normally provided by a biomedical waste carrier). Store anatomical waste in an enclosed storage area that is locked and separate from other supply areas. Anatomical wastes should be stored at a temperature at or below 4 degree. The storage area must be marked as a Biomedical Waste Storage Area and must display the universal biohazard symbol. For portable dental equipment and mobile dental units, transport human tissue wastes in an appropriately labeled and sealed red liner to a dental practice for disposal through an approved waste carrier.
Do not dispose human tissue with the regular garbage.
Either expired or partially-used, pharmaceutical waste must be collected and transferred by a registered hauler to a licensed incinerator. Store pharmaceuticals in labeled, sealed and leak-proof containers in a secure location in such a manner that an accidental spill, will not result in chemicals entering any sanitary sewer or storm drain. If such a location is not available, adequately sized secondary containment should be provided for this equipment or all floor drains in the area must be capped. Do not dispose off expired or excess pharmaceuticals into the garbage, the sewer system or mix them with biomedical wastes. Laboratory/surgical wastes must be collected and transferred by a registered hauler to a licensed incinerator.
The following procedures are suggested to help operators improve their overall environmental performance:
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:
Such practices include the following:
Product substitution practices include using alternative products with less or non-hazardous components or using technologies that generate less toxic or less volume of waste. For example, you may wish to consider alternatives such as:
However, when making any changes, carefully evaluate the new product, material or technology for its effectiveness, durability, ease of use and potential to contain other toxic or hazardous chemicals.
Safe work practices should be incorporated into clinic policy and procedure documents. Some examples of such practices include good housekeeping procedures, routine equipment maintenance, proper storage and labeling and effective record-keeping.
Inspect containers of potentially hazardous materials and wastes regularly to spot damaged or leakage containers. Repackage or place damaged containers in secondary containment immediately. Protect containers from damage by storing in a protected area. Store hazardous, universal, recyclable and non-hazardous wastes in separate and appropriate containers. Place liquid waste containers in secondary containers that can hold 110% of the waste volume.
Know and follow the requirements of your hauler or recycler for each type of waste.
All dental equipment - dental units, waterlines, vacuum systems, X-ray equipment, sterilizers, etc. should be inspected and maintained regularly. Check with the equipment manufacturers for specific recommendations on maintenance. Some guidelines with respect to mercury hygiene are included below.
Waste streams that are designated for recycling/reclamation can be labeled as recyclable materials, e.g. "Scrap metal - to be recycled." Containers that store hazardous waste must be labeled with the words “Hazardous Waste”. The label must also have the following information as required by state law:
You must keep records of the hazardous waste generate whether you get it recycled or disposed offsite. In general, if you send your hazardous waste offsite for recycling or disposal, you must utilize a licensed hauler.
If you transport hazardous waste yourself (“self-haul”) to a licensed facility such as a Community Small Quantity Generator collection location, you should keep a disposal log of the date, type and quantity of waste delivered. Attach the receipt for each shipment to your log.
In exercise of the powers conferred by section 6, 8 and 25 of the Environment (Protection) Act, 1986 the Central Government notifies the rules for the management and handling of bio-medical waste.The Pollution Control Boards in turn are responsible for implementation of the rules.
The Pollution Control Board is the overall regulatory body with respect to Biomedical Waste Management. The board has laid down rules and regulation regarding the correct method of waste classification, segregation,treatment and disposal.
The board has authorized certain waste disposal facilities with government recognition.
Inorder to find an authorized Waste Collection Facility near you,one can contact the Pollution Control Board of their State. There are penalties for not following all the guidelines correctly.