There is growing awareness of an increasing number of occupational asthma cases, which are associated in some way with exposure to isocyanates, particularly for spray painters in the motor vehicle repair (MVR) industry. Isocyanates are also in widespread use in polyurethane manufacturing processes and the companies involved in this work are diverse and dynamic, making it difficult to identify the population potentially exposed. This study identified the different industry sectors where isocyanates were used and provided estimates of the total number of workers potentially exposed. In addition, further information about workplace exposure levels, working practices and exposure control measures were obtained by visiting a limited number of non-MVR companies.
Separate investigations were being made in the MVR sector. It is estimated that approximately 6200 MVR companies use isocyanates, with around 15000 employees directly exposed. In the non-MVR sector, a total of 1657 companies were estimated to use isocyanates, with around 7000 employees directly exposed. In the main, companies carrying out work with the greatest potential for exposure were aware of the health risks and had taken appropriate action to control workers' exposures.
The results of the workplace surveys confirmed that exposure levels were generally low and that it was possible to control air concentrations to below the existing exposure limits with basic exposure control measures. These results suggest that isocyanate related asthma cases could be due to momentary lapses in exposure controls rather than prolonged, high level exposure that might be attributed to ignorance of the health risks and the recommended control measures. Alternatively, it is possible that the existing exposure limits for isocyanates are not set an appropriate level for adequate protection of exposed workers.
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