Waste disposal for dental practices

Most of the chemical work in a dental practice falls into a small number of groups:

• non-infectious and infectious amalgam, including separator contents and capsules
• fixer and developer, in use or left behind after a move to digital imaging
• bulk mercury containers from before encapsulation
• surplus etch, bonding and endodontic materials, and old disinfectant concentrates
• out of date medicines, kept apart from chemical waste

Nitrous oxide and oxygen cylinders, controlled drugs, asbestos and anything that looks unstable are handled as a manual enquiry. Medical gas cylinders usually go back through the supplier, so start by checking with them.

• the number of surgeries, and whether amalgam is placed, removed or both
• separator make and the date its collection vessel was last changed
• type and volume of fixer and developer, and whether the containers are sealed
• any bulk mercury, with its container type and condition
• a list of old materials and concentrates by product name
• who currently collects your sharps, clinical and medicine waste
• opening hours, parking restrictions and a quiet time for collection

Practice managers often apologise for the length of this list. There is no need. A shelf of half-used products from the last three owners is a common finding, and writing it down is the hard part. Once it exists, it can be priced.

The law on amalgam is unusually specific. Article 10 of the retained mercury regulation requires operators of dental facilities where amalgam is used, or where amalgam fillings or teeth containing them are removed, to have amalgam separators. All separators in use have had to retain at least 95% of amalgam particles since 1 January 2021, and they must be maintained according to the manufacturer's instructions.

The same article covers the waste. Amalgam residues, particles and fillings, along with teeth or parts of teeth contaminated by amalgam, must be handled and collected by an authorised waste establishment or undertaking. Practitioners must not release such waste directly or indirectly into the environment. A practice that has stopped placing amalgam but still removes old restorations is still producing amalgam waste, so the separator cannot simply be forgotten.

HTM 07-01 gives the container standard: a specific, marked white bin or container labelled with its contents, with mercury vapour suppressants in amalgam bins. Infectious amalgam stays in separate bins from non-infectious amalgam. Check the suppressant condition when you change containers, and keep the lid closed between uses. Mercury vapour is the hazard in a small, warm surgery store.

Older practices sometimes still have an original bottle of dental mercury. The regulation has required dental amalgam to be used only in pre-dosed encapsulated form since 1 January 2019, and it prohibited dental practitioners from using mercury in bulk form. A bottle in a cupboard is therefore no longer stock. It is waste waiting for a route.

Do not decant it, and never pour it into an amalgam container to tidy up. Leave it closed and stored securely, away from aluminium items and heat. If it has spilled, keep people out of the area and do not use a vacuum, which UK Health Security Agency guidance warns can increase exposure by inhalation. Our page on mercury and heavy metal disposal covers the wider picture.

Wet-film processing has mostly gone, but its chemicals often have not. A practice that went digital years ago may still have a processor in a cupboard, half-full containers of developer and a darkroom shelf nobody has cleared.

These chemicals have a specific classification and specific handling. GOV.UK requires photochemicals and film to be classified under chapter 9 of the List of Waste, and the technical guidance lists fixer solutions as 09 01 04* and water-based developer and activator solutions as 09 01 01*. HTM 07-01 says they should be kept in separate marked containers, typically white, resealable jugs. They should not be mixed with each other or any other waste, and they should be returned to the supplier or sent to a specialised, licensed treatment facility.

Spent fixer contains silver, and silver in the drains is not something a practice should accept. If your processor has ever been plumbed to a drain, raise it with your waste contractor and your water company. Do not decommission it without first draining and collecting the contents as waste. Old lead foil from x-ray film packets is a smaller but common find, and is best listed as well.

The everyday materials of dentistry do not stay fresh forever. Etching gels based on phosphoric acid, bonding agents, impression material components and root canal preparations all end up past their date. Sodium hypochlorite concentrates lose strength with age and should not share a shelf with acidic products. Some historic endodontic products, including formocresol, contain hazardous components that deserve a line of their own on the list.

Medicines are a separate matter from chemicals. Non-hazardous medicines are coded 18 01 09 and hazardous cytotoxic ones 18 01 08*, and HTM 07-01 uses blue-lidded containers for the former. Local anaesthetic cartridges with visible residues may be treated as medicinally contaminated sharps through your clinical stream. Check how your clinical contractor wants them presented before you add anything to a chemical list.

Gypsum models are another separate stream, and HTM 07-01 asks for them to be kept apart from other waste. They are not a chemical matter, but they tend to fill the same store and confuse the picture when a practice is reviewing what it has.

HTM 07-01 places dentists on a two-yearly pre-acceptance audit cycle, with the first audit required before the first batch goes to a permitted facility. Use that visit to confirm that amalgam, fixer, developer and medicines all appear in the waste profile.

Amalgam and fixer are hazardous, so in England each movement needs a consignment note. Part B must give a full description and the correct code, along with weight in kilograms for each code. Keep your copies, along with the consignee returns, in one file with your separator maintenance records. Together they show that amalgam particles were retained, and where they went.

Practice sales are the moment these files get lost. A buyer should ask to see them, and a seller should hand them over with the store. Many dentists also hold old x-ray equipment and sealed radiation records, and these should not be assumed to be part of a chemical clearance. Any radioactive item goes to a manual enquiry.