In the automotive repair and refinishing industries, its no surprise that over the years there have been thousands of cases of occupational asthma reported. Occupational exposure to isocyanate based paints has been the cause of many deaths across the refinishing industry, mainly from suffocation as a result of a severe reaction caused by respiratory sensitisation. Often this can be caused by the isocyanates present in the coatings.
The application of isocyanate based paints requires an operator to spray the product onto a workpiece to achieve a suitable finish. Isocyanate based paints are used in high-performance coatings to achieve a desired quality or finish. The foreseeable risk here may be high due to the nature of the spraying process, this causes isocyanate vapours and particulates to become aerosols, which can be inhaled. Not only are these inhaled, but they can also come into contact with the skin.
As mentioned in our introductory article to isocyanates, occupational exposure to these substances by inhalation or skin contact can result in sensitisation.
Sensitisation of the respiratory system means that the body can react by closing off its respiratory functions to prevent further exposures as a method of trying to protect itself. In the process, the exposed person suffers a severe asthma attack as a result. Once sensitised, a single exposure at any measured level can trigger this type of attack causing severe injury or even a fatality.
Skin exposure works in a similar way. Once the substance touches the skin, the body can react by attempting to fight the contaminant. The result is often a bout of allergic contact dermatitis, a condition caused by being exposed to something which the body reacts with. Again, the skin can become sensitised to isocyanates, and reactions can take place at any level of exposure.
A substance of this nature should be controlled as low as possible. Small doses can result in sensitisation and the impacts can be fatal. It pays to have a COSHH program in place to manage this as a preventative approach.
Where Are Exposures Likely To Occur Outside The Spray Area?
Our occupational hygienists have dealt with cases where exposures to isocyanates were measured low during workplace air monitoring. Operative's who undertook the paint spraying did so within a fully working spray booth wearing air fed respiratory protective equipment. Along with the air testing, routine biological sampling had been carried out. From this, exposures could be determined by sampling for metabolites in the operator's urine. In this instance, the samples indicated that the operators were exposed to high levels of isocyanates, which had entered the body.
When isocyanates enter the body, they are metabolised and then a byproduct of the substance is excreted in the urine. In this instance, exposures were found to be above the biological monitoring guidance values. Following a detailed investigation, it was found that exposures to isocyanates occurred during the paint mixing process. The operative removed his respirator to undertake the task and exposed themselves in the process.
When evaluating exposures to isocyanates, it's important to know that exposures may occur during processes which don't involve spraying. Many of these possible emission sources are discounted when undertaking a COSHH Risk Assessment.
Secondary exposures may occur as a result of the following and/or in the following areas:
The paint mixing process carried out in the designated mixing area where control measures may be relaxed.
The equipment and spray gun cleaning area.
The primer or high-build pre-paint preparation areas.
Areas where coatings are curing (ovens or curing Rooms).
Post application finishing areas - flatting and polishing.
Furthermore, it is important to understand that low levels of isocyanate exposure can cause serious harm. With that information, all COSHH Risk Assessments should be reviewed to take this into consideration by covering locations or processes outside of the spraying process itself.
Wet Flatting Top Coats Posing a Risk to Health
It has been reported that by exposing the skin to semi-cured top coats and lacquers containing isocyanates, the skin can still become sensitised and allergic contact dermatitis can occur as a result of flatting, sanding and possibly polishing the topcoat if it hasn't fully cured.
This shows how minimal exposures can still result in serious negative health effects and that exposures should be controlled to as low as reasonably practicable.
Ideally, paints and coatings that do not contain isocyanates should be used as an alternative product to eliminate part of the hazard. However, it still pays to know that solvent-based paints, the catalyst hardeners and thinners all contain volatile organic compounds, which have detrimental effects on the body even without containing isocyanates.
Do You Need Support with COSHH?
It is hoped that this article goes some way to providing a brief overview of COSHH. If you wish to know more on this subject or need support with your COSHH assessments, exposure monitoring or the testing of your LEV systems, RPE Fit Testing then please feel free to get in touch with us through social media or our website (www.workplacescientifics.com), by email at firstname.lastname@example.org or simply give us a call on 01709 931299.
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