Collins and colleagues(1) focus on canecr risk in their study of more than 15,000 workers at 30 US reinforced-plastic facilities. Yet their demonstration of excess mortality from nonmalignant respiratory disease warrants further discussion. For this cohort of styrene workers, the standardized mortality ratio (SMR) for "bronchitis, emphysema, and asthma" was elevated at 1.35 (95% confidence interval [CI] - 1.17 1.56). The authors attribute this excess of deaths to smoking. Certainly, smoking is a recognized contributor to obstructive lung diseases. Furthermore, the observed inverse relationship with employment duration may appear to be inconsistent with an occupational cause of disease. However, previous studies have demonstrated excess mortality from nonmalignant respiratory disease in short-term styrene workers.