Accepted but unacceptable: 
Exposing clinicians to known carcinogens,
the risk associated with biopsies

It’s about seeing the big picture.

Every day, thousands of healthcare workers are exposed to a variety of substances such as chemicals, fumes and radiation which can, under some circumstances, have a harmful effect on their health.

If exposure to a hazardous substance is not properly controlled, it may cause ill health in several ways. The substance may cause harm by inhalation, absorption through the skin or by being swallowed. After initial exposure, diseases may not appear until years later and so the risk is not fully recognised at the time.

Workplace Exposure Limits (WELs) are set in order to help protect the health of workers. WELs are concentrations of hazardous substances in the air, measured in mg/m3 or parts per million (ppm). The exposure concentration is averaged over a specific time period, referred to as a time-weighted average (TWA). The two TWAs that are generally used are long-term (8 hours) and short-term (15 mins) [1].

Substances that have been assigned a WEL are subject to the requirements of COSHH. COSHH regulations require employers to prevent or control exposure to hazardous substances. For further information go to


It’s the link to biopsies.

A tissue biopsy is one of the most common diagnostic procedures performed in the hospital setting. A doctor will remove a sample of tissue or cells for further diagnostic testing in the lab. The tissue sample must be preserved for pathology to analyse and so the tissue is ‘fixed’ using a preservative chemical solution. The current standard tissue fixative used in diagnostic settings is 10% neutral buffered Formalin containing 4% formaldehyde.

The Formalin is often provided to hospital departments as pre-filled pots where the clinician will remove the lid, transfer the tissue sample into the solution before re-sealing and sending to the laboratory for analysis.

In 2011, formaldehyde was assigned a WEL and was subject to the requirements of COSHH. In 2014, the EU Regulation 605/2014 reclassified it as a class 1b carcinogen [3] and it was added to the IARC (International Agency for Research on Cancer) list of group 1 agents carcinogenic to humans [4]. Other recognised carcinogens in this group include asbestos, arsenic and X-ray radiation. The National Cancer Institute has also issued a warning that ‘Formaldehyde may cause leukaemia in humans’ [5].

Despite being fully aware of the carcinogenic properties of formaldehyde and its 1b classification, it is likely to be years before the exposure risk is completely eliminated. When we look at the timeline for asbestos 1b classification to its use being completely banned, it took approximately 69 years. It is therefore down to individuals to be fully aware of the WELs and take responsibility to limit their own exposure as best as possible.

Although many hospital policies recommend the use of PPE (personal protective equipment) when handling pre-filled Formalin biopsy pots such as gloves, goggles and respirators, this very rarely happens in practise and Formalin exposure remains to be an accepted but unacceptable occupational risk.

In a number of interviews carried out by UK Medical, the perceived risk of dealing with Formalin is still low with clinicians commenting;

“We often spill Formalin on the worktops but just wipe it up with paper towels and pop it in the household waste bin” 

“I was holding the open pot over the patient for the consultant to place the sample in and he knocked the pot all over the patient”.

If you’d like to read the 2019 EU Directive on formaldehyde you can click on the button below

It’s an evolving story.

As the body of evidence builds for the health problems associated with formaldehyde exposure, the recommendations for exposure limits are becoming less and less. Currently, the UK short-term exposure limit is 2ppm over a short-term TWA although known adverse reactions can occur from as low as 0.1ppm [6].

‘Formaldehyde fixatives are routinely used in the healthcare sector across the Union because of their convenience of handling, high degree of accuracy and extreme adaptability. In some Member States, it is foreseeable that the healthcare sector will have difficulties in complying, in the short term, with a limit value of 0.37 mg/m3 or 0.3 ppm.

It is therefore appropriate to introduce for that sector a transitional period of five years, during which the limit value of 0.62 mg/m3 or 0.5 ppm should apply. The healthcare sector should, however, minimise exposure to formaldehyde and is encouraged to respect the limit value of 0.37 mg/m3 or 0.3 ppm during the transitional period where possible’ [7]

Marianne Thyssen, the Commissioner for Employment, Social Affairs, Skills and Labour Mobility said: “Today, the Commission has taken another important step towards fighting work-related cancer and other relevant healthproblems on the work floor… This will improve protection for over 1 million workers in Europe and help create a healthier and safer workplace…” [8]

European hospitals have already begun to make changes to their local policies, with Sweden and Germany reducing the workplace exposure limit to 0.5ppm over a short-term TWA and 0.3ppm over a long-term TWA in the healthcare setting.

How do I know if exposures are below the WEL?

Exposure levels can only be measured by monitoring. This means measuring the substance in the air that the worker breathes while the task is underway. A guidance sheet, Exposure measurement: Air sampling G409  –  tells you what to expect from a competent consultant who provides monitoring services.

In a recent In Vitro study, formaldehyde concentration at the surface of a pre-filled Formalin pot upon removal of the lid was shown to be 13.74ppm. 

The severity of adverse reactions to formaldehyde is directly dependent on the concentration of formaldehyde in solution and the amount of time lapsed before emergency and medical intervention. In addition to cancers, it can also cause a broad range of other significant health problems such as respiratory diseases, neurological disorders and genetic mutations which could affect pregnant women [9].

HSE recognises that when formaldehyde is present in the air at levels exceeding 0.1 ppm, some individuals may experience adverse effects such as watery eyes; burning sensations in the eyes, nose, and throat; coughing; wheezing; nausea; and skin irritation [10].


  • ≥0.05 – 0.5 ppm produces a sensation of irritation in the eyes with burning, itching, redness, and tearing.
  • ≥1 ppm – upper airway irritation. This is the most common respiratory effect reported by workers and can occur over a wide range of concentrations from exposures as low as 0.1 ppm.
  • ≥5 ppm – lower airway irritation characterized by cough, chest tightness and wheezing.
  • ≥50 ppm – can cause severe pulmonary reactions within minutes.
  • ≥100 ppm – immediately dangerous to life.
  • Accidental splash injuries of aqueous solutions of formaldehyde (Formalin) have resulted in a wide range of ocular injuries including corneal opacities and blindness.

It’s about taking responsibility.

COSHH advises ‘where it is not practicable to prevent exposure to a carcinogen, by using an alternative substance or process the employer shall apply the following measure:

  • The total enclosure of the process and handling systems unless this is not reasonably practicable’ [10]


  1. HSE – workplace exposure limits
  2. Nenonen N., Hämäläinen P., Takala J., et al. (2014) Global estimates of occupational accidents and fatal work-related diseases in 2014, Singapore, Workplace Safety & Health Institute.
  7. Brussels, 5.4.2018 COM(2018) 171 final 2018/0081 (COD) Proposal for a DIRECTIVE OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL amending Directive 2004/37/EC on the protection of workers from the risks related to exposure to carcinogens or mutagens at work
  8. (European Commission press release)
  9. (2017). The Control of Substances Hazardous to Health Regulations 1994. [online] Available at: [Accessed 4 Oct. 2017].
  10. gov. (2017). Medical surveillance – Formaldehyde – 1910.1048 App C | Occupational Safety and Health Administration. [online] Available at: [Accessed 4 Oct. 2017]