Testing For Isocyanates

18th January 2018

Updated December 2023

Research by the Health and Safety Executive shows that 400,000 working days are lost in Britain every year due to occupational lung disease. This is caused by several factors but exposure to hazardous chemicals and dust is a big contributor.

So many lost working days is a worrying statistic. But not as worrying as the 12,000 deaths they estimate it causes each year as well. These numbers make one thing clear, employers need to do everything they can to protect workers from these dangers.

When it comes to occupational asthma and lung disease, one of the biggest causes is workplace exposure to isocyanates. In the manufacturing and construction industries in particular, exposure to these compounds is common – and it can have far-reaching consequences.

If you’re concerned about occupational exposure to isocyanates in your workplace – or you aren’t even sure what it is – we’ve put together this blog post as an introduction to the subject.

We’ll discuss what isocyanates are, what workplace exposure limits are and cover how testing for them is a vital part of exposure monitoring.

What are isocyanates?

Isocyanates are a collection of compounds that are used in the production of a wide range of polyurethane products. They are used to manufacture a wide range of products across several different industries, including construction, automobile production and repair, and manufacturing.

How do isocyanates affect the human body?

Isocyanates are highly reactive chemicals and powerful irritants. If the mucous membranes of the eyes, respiratory tract or gastrointestinal tracts are exposed to them, they can cause severe inflammation. Repeated exposure to isocyanates can also lead to sensitisation.

The health effects of isocyanate exposure can vary wildly in type and severity. Irritation is most likely, which can affect the eyes, nose, throat and skin to various extents. The irritation they cause to the respiratory system can also cause chest tightness, difficulty breathing and even asthma.

These compounds are also classed as potential human carcinogens and have been shown to cause cancer in animals.

Can isocyanates be absorbed through the skin?

Isocyanates can also irritate and inflame skin after direct skin exposure. Research suggests they can even be absorbed through the skin leading to further symptoms.

This is further reason to minimise exposure using personal protective equipment and other control measures wherever possible.

What products contain isocyanates?

Isocyanates are used in the production of a wide variety of products including:

  • Polyurethane foam,
  • Insulation materials,
  • Surface coatings,
  • Car seats/furniture,
  • Foam mattresses,
  • Carpet underlay,
  • Packing materials,
  • Polyurethane rubber,
  • Adhesives.

As they are so widely found, eliminating them entirely is almost impossible in most industries. Instead, exposure monitoring, health surveillance and exposure controls are vital measures.

Why test for isocyanate exposure?

Isocyanates are one of the leading causes of occupational asthma in the UK. They can have serious and long-term health effects, but they are almost impossible to avoid completely. Regular testing and isocyanate exposure monitoring can help manage the risks they pose to your employees.

This is not just an ethical duty for your employees, but your legal responsibility under the Health and Safety at Work Act 1974. Under this, you are required to protect the health of your employee

As respiratory sensitisers, exposures to isocyanates should be kept as low as reasonably practicable and this often requires the use of respiratory protective equipment (RPE). Biological monitoring is a simple and cost-effective way of checking that control measures are working and being used correctly.

The Isocyanates Testing Process

Isocyanate exposure testing is a simple, harmless process that causes no ill effects for your employees but will protect their long-term health. Tests can also be carried out regularly without issue.


The most reliable way to test for isocyanate exposure is using urine analysis. The sample should be taken within one hour of potential exposure (after engaging in a ‘normal’ working day). It should also be collected in a specialist bottle, which contains citric acid to preserve its integrity for testing.


It is recommended that you only test for the actual isocyanates used by workers. In most cases, this will only be one or two. This maximises the accuracy of the tests and makes sure your exposure monitoring is relevant.

If you’re unsure which isocyanates you should be monitoring, we can take a look at your safety data sheet to help you identify them.


We have produced guidance on biological monitoring for isocyanates for both employers and employees. HSL scientists will help interpret results from samples that we have analysed where required. There is also a UK guidance value (BMGV) to aid interpretation.

How to protect your employees against isocyanate exposure?

Unfortunately, isocyanates are byproducts of many common manufacturing processes, making it difficult -if not impossible – to avoid completely.

Combined with the serious risks they pose, this makes it vital that you do everything you can to help protect your employees from occupational exposure. As they are difficult to avoid, you must focus on protective measures for preventing exposure rather than eliminating use.

The first way to do this is by using a suitable ventilation system. This should be in place in any area where industrial chemicals and hazardous chemicals such as isocyanates occur. Either an exhaust ventilation system that filters isocyanates or other engineering controls are necessary.

You should also prevent skin exposure using gloves and maintain good occupational hygiene practices including frequent skin washing and removing contaminated clothing before leaving the workplace. Employers should also take care of washing contaminated clothing, to prevent isocyanate exposure in employee’s homes. Eye protection is also vital, with goggles or face shields great options.

Finally, you must supply suitable personal protective equipment (PPE) – and in particular respiratory protective equipment (RPE). This equipment needs to be correctly fitted to provide maximum protection – face fit testing is the only way to make sure your RPE is performing properly.

Using all three of these methods is the best way to minimise your employee’s exposure to isocyanates and reduce the health risks they face as a result.

Keeping your employees safe from isocyanate exposure

If you are concerned about your employees suffering from isocyanate exposure, then testing is the only way to be certain. Exposure levels can

Get in touch with the David Barber Occupation Health team today for more guidance on Health Surveillance.

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