Chemical considerations for dental waste

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  Posted by: Dental Design      12th January 2024

Dental waste is part and parcel of everyday care. It cannot be avoided, but should be properly managed. A variety of guidelines are in place to hep ensure that dental professionals safely and appropriately dispose of waste products, but they should also have a comprehensive understanding of why these rules are in place. With this, awareness of the appropriate measures can increase, and dentistry’s environmental impact can be controlled.

Products used in a variety of treatment processes can cause immense damage when improperly disposed of.  There are many items that could contribute to physical pollution – think plastic waste[1] – but so much of the waste from modern dentistry also poses an immense chemical threat.

Amalgam effects

Perhaps the most well-known environmental threat from within dentistry, amalgam contributes heavily to mercury pollution. Measures are already in place to reduce its prevalence in day-to-day care.[2]

Dental amalgam’s contribution to the world’s overall mercury pollution is laid bare in the Global Mercury Assessment 2018, from the United Nations Environment Programme. It’s estimated that in 2010 dental amalgam contributed to between 21-32% of overall EU mercury emissions to air, and 9-13% to surface water.[3]

Its presence in the environment is not just dangerous to the world around us, but also ourselves. Most human exposure is through fish and shellfish; by contaminating water sources, methylmercury can build up in the creatures’ bodies. Whilst most people have trace levels of the compound in their body already, it can be particularly harmful to newborns. In the United States alone, it is estimated that more than 75,000 babies are born each year with an increased risk of learning difficulties due to in-utero exposure to methylmercury.[4]

On land, the presence of mercury in soil may prove toxic for various microbes, invertebrates and plants, when at sufficient levels.[5]

To do their part in relieving this environmental burden, dental practices must be equipped with an amalgam separator, with authorised waste management establishments handling the refuse.[6] This way, wastewater and sewage system contamination is minimised, and the mercury can undergo a safe recovery process.

Safety with silver

Whilst X-ray systems are conventionally associated with harm through excessive radiation exposure, waste products from the conventional process may be incredibly dangerous on a larger scale. Notably, X-ray photographic fixer and developer provide a host of issues when improperly managed.

These products pose a threat due to their high silver content. Releasing silver in the quantities that are commonly present – concentrations of 5ppm or more, are considered toxic hazardous waste[7] – can make water unfit to drink, harm aquatic life, damage crop fields and corrode equipment that uses the contaminated water.[8]

Dental professionals must differentiate the fixer and developer when wasting, storing them in separate containers or areas to prevent physical contact and possible contamination.[9] HTM 07-01 states that they should either be returned to the supplier or sent to a specialised, licensed treatment facility.[10]

A model process

Another potential environmental threat when improperly disposed of is gypsum. Its common use in dentistry is to fabricate three-dimensional models when treatment planning for orthodontic, restorative and prosthetic care. However, once these casts are no longer of use, they can’t simply be thrown away to go to landfill. They require specialised provisions to minimise their potential harm.

Gypsum is made up of calcium sulphate and water.[11] When at landfill, it becomes subject to wet, anaerobic conditions, ideal for the activity of sulphate reducing bacteria.[12] These organisms use sulphate as an oxygen source, leaving sulphide as a by-product, which may subsequently create hydrogen sulphide.11

The result is a colourless gas with a distinctive rotten egg odour, which can be extremely toxic and harmful to individuals who come into contact with it.[13] These effects range from irritation of the eyes, nose and throat (with breathing difficulties in tow), to neurological issues, namely headaches and poor memory in the short- and long-term, and potentially limited motor function.[14]

Dental professionals must segregate gypsum materials and ensure they reach a specialist landfill site.[15] It’s preferred that the product is sent to a permitted facility for recovery.10 To achieve this, designated gypsum waste containers should be established, and dental professionals should be actively aware of their necessity and location.

Finding regulation abiding solutions that encourage your practice to waste safely is essential. Initial Medical offers Eco Gypsum Waste Containers, which provide safe storage and facilitate the correct disposal of gypsum products. Plus, they are made out of 100% recycled polymers, for a green solution.

Initial Medical will also help you fulfil your legal requirements by handling the segregation of your waste, before disposing of it at an appropriate site. Take your waste management even further with Initial Medical’s Pure Motion® amalgam separator, removing up to 99.8% from your wastewater systems, with installation that doesn’t require practice downtime.

Without effective solutions to waste management throughout the practice, the environment locally and further afield can suffer greatly. It is the responsibility of the dental professional to ensure best practices are followed, and doing so can make the world a safer and healthier place to live.

To find out more, get in touch at 0808 304 7411 or visit the website today 

About Initial Medical

Initial Medical set the standard in healthcare and infectious waste management in the UK, providing a reliable, effective and fully compliant service built around customer needs and delivered by our highly trained local teams.  We are ISO 9001:2015 accredited, with technology fully integrated into our operations, providing full traceability of service delivery, electronic waste documentation and the best customer experience possible. We also offer innovative healthcare waste management services and infection control products, to help break the chain of transmission and prevent cross contamination.  

Initial Medical are a company with a ‘World Class’ Health and Safety record, and ISO 45001:2018 accreditation. We are also accredited to ISO 14001:2015 environmental standards, and pride ourselves on our sustainable approach with a focus on delivering eco-friendly products and operational solutions.

Media enquiries:

For more information, please contact:

01227 265700

Rebecca Waters, Category Manager, Initial Medical

Rebecca has worked in the Healthcare sector for the past 17years and was a Research Chemist with Bayer Cropscience prior to joining Rentokil Initial in 2003.  She keeps up to date on all developments within the clinical waste management industry and is an active member of the CIWM, SMDSA and BDIA.  

[1] Miller, S. A. (2020). Five misperceptions surrounding the environmental impacts of single-use plastic. Environmental Science & Technology54(22), 14143-14151.

[2] Johnston, L., (2019). Amalgam and the environment. British Dental Journal. 226, 640

[3] AMAP, UN Environment, (2019). Technical Background Report for the Global Mercury Assessment 2018. (Online) Available at: [Accessed October 2023]

[4] United States Environmental Protection Agency, (2023). Mercury Emissions: The Global Context. (Online) Available at: [Accessed October 2023]

[5] Tipping, E., Wadsworth, R. A., Norris, D. A., Hall, J. R., & Ilyin, I. (2011). Long-term mercury dynamics in UK soils. Environmental Pollution159(12), 3474-3483.

[6] Care Quality Commission, (2023). Dental mythbuster 1: Use and disposal of dental amalgam. (Online) Available at: [Accessed October 2023]

[7] Rupiasih, N. N., Purnomo, R. R., & Sumadiyasa, M. (2016, April). Preparation and application of chitosan membranes to filter silver from X-ray film processing wastes. In Journal of Physics: Conference Series (Vol. 710, No. 1, p. 012009). IOP Publishing.

[8] Galarpe, V. R. K. R., & Leopoldo, G. D. (2017). Potential recovery of silver (Ag) from X-ray fixer waste by alkaline treatment. Engineering, Technology & Applied Science Research7(5), 2094-2097.

[9] Environment Agency, (2021). Healthcare waste: appropriate measures for permitted facilities. (Online) Available at: [Accessed October 2023]

[10] NHS England, (2022). Health Technical Memorandum 07-01: Safe and sustainable management of healthcare waste. (Online) Available at: [Accessed October 2023]


[11] Panza, D., & Belgiorno, V. (2010). Hydrogen sulphide removal from landfill gas. Process Safety and Environmental Protection88(6), 420-424.

[12] Meyer-Dombard, D. A. R., Bogner, J. E., & Malas, J. (2020). A review of landfill microbiology and ecology: A call for modernization with ‘next generation’ technology. Frontiers in Microbiology11, 1127.

[13] Public Health England, (2009). Hydrogen Sulphide General Information. (Online) Available at:[Accessed October 2023]

[14] Martin, N., Sheppard, M., Gorasia, G., Arora, P., Cooper, M., & Mulligan, S. (2021). Awareness and barriers to sustainability in dentistry: A scoping review. Journal of Dentistry112, 103735.

[15] Environment Agency, (2020). Dispose of waste to landfill. (Online) Available at: [Accessed September 2023]


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