NHS pathology staff face unsafe formaldehyde exposure levels

Routine exposure to harmful levels of the human tissue preservative formaldehyde are risking the health of thousands of NHS staff working in pathology departments across the UK, due to poor monitoring and control, finds an analysis of Freedom of Information (FOI) requests, published online in the journal Occupational & Environmental Medicine. 

Airborne levels of what is a known carcinogen exceed 8 hour European Union (EU) workplace limits in 7 out of 10 NHS pathology departments across the UK, the FOI responses indicate.

The findings prompt the researchers to call for urgent national regulatory intervention to protect the health of NHS employees working in these labs, who number 28,000 in England alone.

In 2024 the US Environmental Protection Agency stated that formaldehyde presents an "unreasonable risk of injury to human health," note the researchers. 

Due to increasing concern over formaldehyde's toxicity, the EU introduced new binding formaldehyde workplace exposure limits in 2021 of 0.3 parts per million (ppm) (long term 8 hour time-weighted average) and 0.6 ppm (15 minute short-term exposure limit). 

But the UK left the EU in 2020, so didn't have to adopt them, instead maintaining the world's highest formaldehyde workplace exposure limit of 2ppm for both long and short term exposures. 

The extent of formaldehyde exposure among the UK's pathology lab workers employed by the NHS isn't known, so the researchers made FOI requests of 122 NHS Trusts: 102 in England; 10 in Scotland; 6 in Wales; and 4 in Northern Ireland.

They requested 12 months (2024-25) of formaldehyde airborne monitoring results collected as part of the regular scheduled monitoring protocols of cell pathology departments.

They wanted to know how often scheduled formaldehyde airborne monitoring was undertaken; how often it had been done in the preceding 12 months; and the approximate annual caseload of surgical specimens.

All 122 NHS trusts responded to the FOI requests, 85% (104) of which were able to disclose a full 12-month record of monitoring on behalf of 117 path labs across the UK. 

In all, 1,715,516 distinct monitoring events were disclosed. The average annual caseload of surgical specimens reported by labs with a suitable record of formaldehyde airborne monitoring was 36,959.

Despite handling tens of thousands of surgical specimens every year, monitoring was infrequent. Nearly 3 out of 4 (73%) sites measured airborne levels once a week or less: 15% of them only monitored it quarterly, and 4% only once a year.

And airborne levels were inadequately controlled. The EU long term workplace exposure limit was regularly exceeded at 70% of sites. Only 11% of sites carrying out frequent monitoring (once daily or more) didn't regularly exceed it.

While none of the sites exceeded the UK short and long term workplace exposure levels, nearly a third (30%; 35) had recorded an airborne formaldehyde level above 2 ppm at least once in the preceding 12 months.

"A substantial body of evidence demonstrates that formaldehyde is associated with myriad deleterious health effects at concentrations well below UK [workplace exposure levels]," point out the researchers.

Long term formaldehyde inhalation is known to affect respiratory and reproductive health, and increase the risk of cancers of the nose and throat and leukaemia. And emerging evidence suggests that it also heightens the risks of motor neuron disease and cognitive impairment, they explain.

"The relevance of our data is, however, not limited to healthcare environments. Industries with occupational exposure to formaldehyde also include manufacturing, construction and myriad others that employ many tens of thousands of people in the UK," they argue.

They conclude: "Urgent national regulatory intervention is now warranted to improve the occupational hygiene of NHS cell pathology departments. 

"This will require a combination of upgraded infrastructure, more regular personal exposure monitoring, better employee education on basic laboratory practice and occupational health risks, improved access to appropriate personal protective equipment, management accountability for occupational health, and external oversight by the Health and Safety Executive."

In a linked editorial, Professor Hans Kromhout of Utrecht University, and Dr Martie van Tongeren, of Manchester University's Centre for Occupational and Environmental Health, highlight the importance of the findings, but also some limitations.

"The reported data lacks essential information concerning measurement and analytical methods, measurement strategy, duration of sampling, etc….It is also unknown whether the formaldehyde data..were based on personal or stationary sampling, which can give very different results."

Nevertheless, they add: "Despite these limitations, it is obvious that exposure levels to formaldehyde can be high in NHS cell pathology departments, and that levels are not reduced to "as low as reasonably practicable," as outlined by the Control of Substances Hazardous to Health Regulations 2002 (COSHH).

They conclude: "There are currently no common guidelines or standards for the control and monitoring of formaldehyde in the NHS, and based on the evidence presented in the paper, such guidelines are urgently needed."

And the UK workplace exposure levels for formaldehyde should be brought in line with those in the EU, they advocate.