Why should Isocyanate Exposure be monitored?
Isocyanates are highly reactive chemicals used in making a variety of products, including paints, foams and glues. Isocyanates are one of the leading causes of occupational asthma in the UK. 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). Occupational asthma can cause serious ill health and result in major changes to the lifestyle of affected people. In some cases, the sufferer has to change jobs to stop their asthma symptoms from getting worse. However, if adequate control measures are in place the condition is preventable. Biological monitoring is a simple and cost-effective way of checking that control measures are working and being used correctly.
Where are Isocyanates used?
Isocyanates are widely used in industry but are particularly prevalent in spray paint, foam and polyurethane manufacture and in adhesives. Healthscreen recommends that vehicle spray painters undertake biological monitoring annually to check that exposure is being adequately controlled. Biological Monitoring can be arranged as part of your health surveillance (health surveillance is required for workers using isocyanates). Isocyanates are most prevalent in the motor vehicle repair (MVR) industry, for example:
- Two-pack spray paints (e.g. hexamethylene diisocyanate, HDI).
- Some glues and hard wearing plastics (e.g. toluene diisocyanate, TDI).
- Making, cutting, grinding or heating polyurethane foams (e.g. methylene diphenylene diisocyanate, MDI).
- Production of polyurethane paints, varnishes and elastomers (e.g. isophorone diisocyanate, IPDI).
To control the risk of asthma, isocyanate exposure in your employees needs to be kept at very low levels. Even brief exposures to isocyanates can cause sensitisation. Once a person has been sensitised, exposure to low levels can still cause an asthma attack. The law requires employers to control exposure to isocyanates to a level which is as low as is reasonably practicable. But as an employer, how can you tell whether you are doing enough to control the exposure of your employees to isocyanates?
The Health & Safety Laboratory (HSL) has developed a method for analysing breakdown products of isocyanates in urine. The method can measure exposure to HDI, TDI, MDI and IPDI, either separately or as mixed exposures. Samples should be taken immediately post-shift (or post-exposure, if exposure is intermittent or ‘task-based’). If sampling is for TDI or a mixture of isocyanates, samples should be collected in special bottles containing citric acid.
Why use Biological Monitoring for Isocyanates?
Biological Monitoring can measure exactly how much of a chemical has entered a person’s body, rather than how much is in the environment they work in. Controlling of exposure to isocyanates relies on engineering controls such as spray booths and respiratory protective equipment such as air fed breathing apparatus (visors). By using a biological monitoring service you will know whether control measures like these are working and whether they are being used correctly.
Are your control measures preventing exposure?
According to the Health and Safety Executive (Sector Information Minute SIM 03/2006/04), the only practical way of measuring a paint sprayer’s exposure to isocyanate is by analysis of isocyanate metabolites in a urine sample. This is a validated technique to determine whether a paint sprayer wearing air fed breathing apparatus is being adequately protected and a benchmark against which to compare exposure measurement results.
What do these results mean?
BM analysis does not give any information about general health effects, it is simply a measure of the effectiveness of your exposure control measures. Nevertheless, it is important that the purpose of BM is clearly explained to each individual taking part and that their informed consent is obtained.
If these things happen in your Bodyshop, you need BM
- Painters not wearing an air fed mask or visor at all?
- Painters not wearing the correct air fed masks or visors?
- Painters lifting visors to take a closer look at the job?
- Painters spraying above head height?
- Non-observance of the correct clearance time in spray booths?
- Non protected personnel entering spray areas to speak to painters during spraying?
If any of this happens in your business, your employees may be at risk of being exposed to isocyanates
Healthscreen offers biological monitoring analysis for HDI and IPDI (found in spray paints), TDI (foams and glues) and MDI (resins and hardeners) across the United Kingdom. A urine sample is required and should be taken at the end of a period of potential exposure. Sampling should reflect normal working practice. Urine samples should be collected in bottles containing a citric acid preservative. Healthscreen provides bottles and packaging as part of the analysis cost.