An analysis of Freedom of Information (FOI) requests published online in the journal finds that the health of thousands of NHS staff working in pathology departments across the UK is at risk due to routine exposure to harmful levels of the human tissue preservative formaldehyde due to poor monitoring and controls. Occupational and environmental medicine.
Seven out of 10 NHS pathology departments across the UK have airborne levels of known carcinogens exceeding the European Union’s eight-hour workplace limit, an FOI response showed.
The findings have prompted researchers to call for urgent intervention by national regulators to protect the health of 28,000 NHS workers in these laboratories in the UK alone.
In 2024, the U.S. Environmental Protection Agency said formaldehyde poses an “unreasonable risk of harm to human health,” the researchers note.
Due to growing concerns about formaldehyde toxicity, in 2021 the EU introduced binding new workplace formaldehyde exposure limits of 0.3 ppm (long-term 8-hour time-weighted average) and 0.6 ppm (15-minute short-term exposure limit).
However, as the UK left the EU in 2020, it was not required to adopt them and instead maintained formaldehyde workplace exposure limits of 2ppm, the highest in the world for both long-term and short-term exposure.
The extent of formaldehyde exposure among UK pathology laboratory staff employed by the NHS is unknown, so researchers made FOI requests to 122 NHS trusts. 10 in Scotland. 6th place in Wales. 4 in Northern Ireland.
They requested that 12 months (2024-2025) of formaldehyde airborne monitoring results be collected as part of the cytopathology department’s regularly scheduled monitoring protocols.
They wanted to know how often airborne formaldehyde monitoring was conducted systematically. How often has it happened in the past 12 months? and approximate annual case numbers of surgical specimens.
All 122 NHS Trusts responded to FOI requests, of which 85% (104) were able to disclose full 12-month monitoring records on behalf of 117 PathLabs across the UK.
A total of 1,715,516 individual monitoring events were published. The average annual number of surgical specimen cases reported by laboratories with adequate records of formaldehyde airborne monitoring was 36,959.
Despite handling tens of thousands of surgical specimens each year, monitoring was infrequent. Almost three out of four (73%) facilities measured airborne concentrations weekly or less, with 15% measuring only quarterly and 4% only once a year.
Additionally, airborne levels were poorly controlled. EU long-term workplace exposure limits were regularly exceeded in 70% of facilities. Only 11% of sites with frequent monitoring (once a day or more) regularly exceed this value.
Although none of the facilities exceeded UK short-term and long-term workplace exposure levels, almost a third (30%, 35) recorded atmospheric formaldehyde levels above 2 ppm at least once in the previous 12 months.
“A growing body of evidence shows that formaldehyde, at concentrations well below UK (workplace exposure levels), is associated with a myriad of adverse health effects,” the researchers note.
Long-term inhalation of formaldehyde is known to affect respiratory and reproductive health and increase the risk of nose and throat cancer and leukemia. And new evidence suggests it may also increase the risk of motor neuron disease and cognitive impairment, they explain.
“However, the relevance of our data is not limited to healthcare settings. Industries with occupational exposure to formaldehyde also include manufacturing, construction and countless other industries that employ tens of thousands of people in the UK,” they argue.
They said: “Urgent national regulatory intervention is now warranted to improve occupational health in NHS cytopathology units.
“This will require a combination of infrastructure upgrades, more regular personal exposure monitoring, increased employee training on basic testing practices and occupational health risks, improved access to appropriate personal protective equipment, management responsibility for occupational health, and external oversight by health and safety executives.”
In a linked editorial, Professor Hans Kromhout from Utrecht University and Dr Marty van Tongeren from the Center for Industrial and Environmental Health at the University of Manchester highlight the importance of the study results, but there are also some limitations.
“The reported data lacks important information regarding measurement and analysis methods, measurement strategies, sampling periods, etc. It is also unclear whether the formaldehyde data are based on personal or routine sampling, which could lead to very different results.”
Nevertheless, they added: “Despite these restrictions, it is clear that levels of exposure to formaldehyde can be high in NHS cytopathology departments and that levels have not been reduced to ‘as low as reasonably practicable’ as outlined in the Control of Substances Hazardous to Health Regulations 2002 (COSHH).
They concluded that “currently no common guidelines or standards exist for the management and monitoring of formaldehyde in the NHS and, based on the evidence presented in the paper, such guidelines are urgently needed.”
And they argue that formaldehyde exposure levels in the UK’s workplaces need to be brought in line with EU levels.
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Reference magazines:
Presa, M., Yates, R. L. (2026). Under the microscope: Formaldehyde exposure in the pathology department of the UK National Health Service. Occupational and environmental medicine. DOI: 10.1136/oemed-2025-110545. https://oem.bmj.com/content/early/2026/05/04/oemed-2025-110545
