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Isocyanate exposure and occupational asthma: a case-referent study.
S K Meredith1, J Bugler, R L Clark
1MRC Clinical Trials Unit, 222 Euston Road, London NW1 2DA, UK.
Occupational and Environmental Medicine
|November 15, 2000
Summary
Occupational asthma can develop from low isocyanate exposure, with higher exposure increasing risk. Atopy and smoking may increase the odds of developing this condition.
Area of Science:
- Occupational health
- Toxicology
- Respiratory medicine
Background:
- Isocyanates are common industrial chemicals linked to occupational asthma.
- The role of individual factors like atopy and smoking in isocyanate-induced asthma requires further clarification.
Purpose of the Study:
- To quantify the relationship between isocyanate exposure and occupational asthma.
- To investigate the influence of atopy and smoking on the development of occupational asthma.
Main Methods:
- A case-referent study was conducted in two manufacturing companies (A and B).
- Exposure levels were estimated using existing measurements and personal monitoring.
- Cases of occupational asthma were compared with referents without the disease, matched for work history and demographics.
Main Results:
- Higher time-weighted average (TWA) isocyanate exposures were observed in cases compared to referents at the time of asthma onset.
- An 8-hour TWA exposure above 1.125 ppb was associated with an increased odds ratio for occupational asthma (OR 3.2).
- Atopy (OR 3.5) and smoking (OR 2.1) were associated with increased odds of occupational asthma, independent of exposure levels.
Conclusions:
- Occupational asthma can occur even at low isocyanate concentrations, with risk increasing with exposure levels.
- Atopy and smoking appear to be risk factors for developing isocyanate-induced occupational asthma.
- Individual susceptibility factors do not alter the estimated risk associated with isocyanate exposure itself.