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Dental Office Hazardous Waste
The most common sources of hazardous waste at dental offices are amalgam waste, containing mercury and silver; x-ray fixer and film, containing silver; lead foil and pharmaceutical waste. Lead, mercury and silver can be dangerous to human health and can pollute the environment if not properly handled and disposed of. Metals and pharmaceuticals in wastewater cannot be completely removed by the wastewater treatment plant and end up in rivers, lakes and streams, where they can negatively impact wildlife.
Dental offices may also produce the following hazardous waste: disinfectants and cold sterilants; developer system cleaners which may contain chromium; vapor sterilizer chemicals and used fluorescent bulbs. This fact sheet describes hazardous wastes generated by dental offices and discusses pollution prevention options, as well as management and disposal options.
Amalgam
Amalgam can contribute to many waste streams in the dental office. Amalgam particles are a major source of mercury in the sewer system. They should be captured on filters, traps and in approved amalgam separators then properly managed.
Wastewater from dental chairs, where amalgam is placed or removed from patients’ mouths, is considered hazardous waste. For dental offices in the Twin Cities metropolitan area, a program developed by the Minnesota Dental Association (MDA) and Metropolitan Council Environmental Services (MCES) permits disposal of this wastewater to the sanitary sewer if an approved amalgam separator is appropriately used prior to discharge. Appropriate use means the separators are maintained and operated according to the manufacturer’s specifications and the flow rate is not exceeded. Exceeding the flow rate inhibits adequate removal of the amalgam particles.
For dental offices outside the Twin Cities area, use of an amalgam separator is encouraged by both the MDA and the Minnesota Pollution Control Agency (MPCA). If an amalgam separator is not used, a mercury discharge limit may have to be met or wastewater collected and managed as hazardous waste. Talk to your local wastewater publicly owned treatment works (POTW) about requirements. For a list of approved amalgam separators see the MDA Web page.
Traps, vacuum filters and separators catch particles of amalgam, which may include mercury so proper disposal and maintenance is important. Follow manufacturer’s instructions.
Any mercury-contaminated wastes from preparing, mixing and administering amalgam, as well as used and unused amalgam capsules contaminated with mercury must be properly managed—either recycled or managed as a hazardous waste.
Amalgam on extracted teeth should be managed as recyclable mercury waste. The teeth can be disinfected prior to shipping. But, storing the teeth in disinfectant can result in mercury leaching into the solution, possibly creating an additional hazardous waste.
Reducing Amalgam Waste
While composite materials in general have a shorter life span than amalgam, especially for molar applications, composite materials are improving. Dentists in countries such as Finland use composite materials in 79 percent of their restorations. Other materials such as composite, ceramic, gold, porcelain and glass ionomers can be used in lieu of amalgam for certain restorations. As composites improve, more insurance companies are allowing for their reimbursement.
Pharmaceuticals
Many pharmaceuticals used in a dental clinic become hazardous waste when disposed of or when they become “inherently waste like” (partially used, leaking or cannot be credited via reverse distribution). Hazardous waste pharmaceuticals can include medications used for anesthesia and pain relief as well as those medications in emergency kits and crash carts. Examples of hazardous waste pharmaceuticals include: albuterol inhaler, ammonia inhalants, anesthetics, epinephrine (including vials, pens and needles), Nitrolingual pump spray and pain medications. If drugs are accepted for reverse distribution, they are not considered waste.
When discarded, epinephrine is considered a P-listed hazardous waste and special rules must be followed. See the MPCA fact sheet P List of Acute Hazardous Wastes.
Reducing Pharmaceutical Waste
Expired drugs are often wasted, increasing costs and the volume of hazardous waste. Drug waste can be reduced by reviewing use history and ordering appropriately. Eliminating or carefully accepting drug samples can also reduce or eliminate pharmaceutical waste. Epinephrine waste can be reduced by eliminating crash carts where possible.
Other Hazardous Waste
Used X-ray Fixer
Recycling companies will reclaim silver from used fixer. Do not mix fixer and developer. Doing so will increase the overall volume of hazardous waste. Installing a silver recovery unit at the end of the x-ray processing unit is another option for disposing of used x-ray fixer. The recovery unit must be sized to handle the quantity of fixer waste generated. Properly operating and maintaining equipment will reduce silver levels in the wastewater. Recovered silver can be sold to a metal reclaimer and treated fixer can be disposed of down a drain that is connected to a wastewater treatment plant. If you are connected to a septic system do not dispose of treated fixer down the drain.
X-ray Film
Silver can be reclaimed from x-ray film. Film with large dark areas contain more silver than film with smaller dark areas. Reclamation companies that accept used fixer also often take x-ray film.
Lead Foil and Lead Shielding
In Minnesota lead is a listed hazardous waste and it must be recycled or disposed of as hazardous waste. Reclamation companies that accept used fixer or your dental supply company may recycle lead foil.
Developer
Used developer can be disposed of down a drain that is connected to a POTW. If your facility is not connected to a POTW, arrange for disposal at a facility that is, such as a hospital.
Developer Systems Cleaner
If a cleaner contains chromium or any “chromate,” it must be managed as hazardous waste. Check the material safety data sheet (MSDS). Cleaners that do not contain chromium may be easier and cheaper to use. Or, find a cleaning service to clean the developing unit at your clinic and properly dispose of the chromium-containing waste cleaner.
Some developer system cleaners are corrosive containing acids or may contain oxidizing chemicals. These chemicals should be evaluated for hazardous waste characteristics prior to disposal. They must be permitted to be disposed of via the sanitary sewer and may require neutralization.
Reducing X-ray Waste
Waste such as spent fixer, developer, cleaners and x-rays can be eliminated by substituting digital imaging systems. Digital imaging is a dry system, no liquid chemicals are used in taking and developing the image. Because digital imaging uses a laser and computer system, no waste is produced from the imaging process. Ultimately waste will include outdated electronics, video cards and possibly paper images, if they are printed.
A Michigan orthodontic business that purchased a digital x-ray machine anticipated that it would eliminate the annual use of over 200 gallons of photographic development chemicals containing heavy metals such as silver and lead.
Vapor Sterilizer Chemicals
MPCA regulates the disposal of unused vapor sterilizer chemicals. They are highly flammable and contain formaldehyde. Disposal of these materials is regulated by the MPCA, POTW and/or the county. If small quantities of these chemicals must be disposed, contact your local POTW to determine if the sewage treatment system can handle the amount you have. If not, these chemicals must be disposed of as hazardous waste.
Ultrasonic Cleaners
These cleaners may be enzymatic, or contain alcohol, glutaraldehyde, or potassium hydroxide. The least toxic of these are the enzymes, although they may contain hazardous ingredients such as butoxy ethanol or nonylphenylethoxylates. After use these cleaners must be evaluated to determine if they are hazardous waste. They may be Minnesota Lethal, flammable or corrosive. Hazardous waste can be minimized by using enzymatic cleaners without butoxyethanol or other hazardous materials. Used cleaners may be disposed to the sanitary sewer with permission.
Disinfectants and Cold Sterilants
Hydrogen peroxide, formaldehyde, glutaraldehyde or other disinfectants are considered hazardous waste in concentrated form. Generally, diluted product used for its intended purpose can be disposed of via the sanitary sewer. Contact you local POTW for more information.
Managing Hazardous Waste
Hazardous waste must be stored in a closed, covered container; labeled as “Hazardous Waste” with a descriptive name of the waste and the date the container was filled; and sent to a permitted hazardous waste facility for disposal. For more information on hazardous waste management, see MPCA’ s 10 Steps to Compliance or call your metropolitan county.
Fluorescent bulbs and lamps should be recycled. Xcel Energy Disposal Services accepts waste lamps and ballasts from customers.
Managing Other Waste
Blood
Swabs or dressings saturated with blood are regulated by infectious waste rules. Materials containing only small amounts of blood can be placed in the garbage. For more information, contact the MPCA at 651/296-6300 or 800/657-3864.
Sharps
Scalpels, needles and other sharp objects that can puncture the skin are regulated by infectious waste rules. These materials must be placed in a puncture-proof container, labeled “Used Sharps” and disposed of properly by a medical waste service.
Licensing and Reporting
For reporting and licensing procedures, and to obtain the U.S. Environmental Protection Agency identification number needed to transfer hazardous dental waste to a processor, contact the proper authorities. Dental offices located in Twin Cities metropolitan counties should contact their county. Other dental offices call the MPCA.
| Regulatory contacts: |
| Anoka |
763/422-7093 |
| Carver |
952/361-1800 |
| Dakota |
952/891-7557 |
| Hennepin |
612/348-3777 |
| Ramsey |
651/773-4466 |
| Scott |
952/496-8177 |
| Washington |
651/430-6655 |
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| MCES |
651/602-4703 |
| MPCA Generator Technical Assistance Unit |
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800/657-3864 |
For More Information
More information about disinfectants can be found in MnTAP’s fact sheet Disinfection Best Management Practices [#73].
MnTAP has a variety of technical assistance services available to help Minnesota businesses implement industry-tailored solutions that maximize resource efficiency, prevent pollution, increase energy efficiency, and reduce costs.Our information resources are available online. Or, call MnTAP at 612.624.1300 or 800.247.0015 from greater Minnesota for personal assistance.
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