Cyclopentanone: an unexpected airborne pollutant in a plastics moulding plant.
Keywords:occupational exposure ; cyclopentanone ; tetrahydrofuran ; plastics moulding; thermal degradation; risk assessment, risk control strategies
A Local Unit of the Italian Public Health Service for Occupational Safety and Health was consulted by a male worker complaining an acute respiratory distress, sharply arisen during his previous nocturnal work shift in a plastics moulding plant.
Some months before, a female worker from the same plant had been sent to consultation at the above mentioned Local Unit, for suffering hacking cough, thoracic heaviness and mild dyspnoea every time she entered the workshop at the beginning of the workweek.
The plant produces soles and components for footwear by injection moulding of a variety of thermoplastic compounds (mainly thermoplastic rubber and thermoplastic polyurethane); many batches of these compounds are charged with a wide range of pigments.
For the above, the Public Health Service Local Unit activated an inspection inside the plant, evaluating the results of samplings of airborne total dusts and airborne chemicals performed by the firm consultants: subsequently, both the firm consultants and the Public Health Service carried out a specific monitoring of airborne chemicals applying the respective standard techniques.
The early results from both the sources showed no significant presence of aldehydes and other VOCs (Volatile Organic Compounds), with the sole relevant exceptions of an, at the moment, undetermined chemical revealed, in all the first five samplings for aldehydes collected by the Public Health Service, with responses ranging from 1484 to 1598 µg / m3, and of a minor concentration of tetrahydrofuran in two samples for VOCs (standard set) collected by the Public Health Service.
A subsequent series of three quali-quantitative samplings performed by the Public Health Service at three different plastic presses by means of a different sampling technique (adsorption onto Tenax tubes) revealed an unexpected, outstanding presence of cyclopentanone, corresponding to the above mentioned, initially unidentified chemical.
After a set of interventions determining a substantial amelioration of the general forced ventilation inside the workshop, further samplings were performed by both the firm consultants and the Local Unit of the Public Health Service, searching for both aldehydes and other VOCs (standard set) and revealing no persisting considerable presence of cyclopentanone and other airborne relevant pollutants, except for some tetrahydrofuran in the Public Health Service samples. No other cases of respiratory disease subsequently emerged.
Cyclopentanone is a fragrant chemical whose toxic potential has been poorly studied. It is reasonable that cyclopentanone vapours, such as vapours of other chemicals from the thermal degradation products of thermoplastic blends, develop inside the plastic moulding workshop in particular conditions when some compounds are overheated; this situation could be accompanied by dusts’ emission too. The two reported cases, classifiable as “sentinel events” though clinically not weighty, reasonably were a consequence of an occurrence of such situations.
In any case, the reported results suggest that standard samplings of VOCs not always can reveal all the relevant species in a plastic moulding workshop and that, especially in the presence of “sentinel events” such as cases of respiratory distress, this kind of work environments needs both close examinations and competent risk assessments, and specific preventive interventions.
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