The study looked at four groups of apprentices: painters, machinists, electricians and insulators; all of these 348 apprentices were in their early 20s in 1988. The researchers evaluated medical records of the apprentices' physician visits from 1991 to 2002.
They found that those workers who developed the worst sensitivity to lung irritants over the first two years of employment were more likely to visit the doctor for both asthma and bronchitis in later years. Machinists were most likely to have the worst cases of new sensitivity to lung irritants.
"We know that exposure to irritants in the workplace can change people's lung function later in life, but we can't predict who will go on to develop lung disease," says lead researcher Cheryl Peters, of the Occupational and Environmental Hygiene Department at the University of British Columbia in Vancouver. "We hope this study may begin to answer that question. We are following workers over time and looking at patterns in their healthcare utilization records." She noted that this is part of a larger study which is also recording workers' physical measurements, such as lung function. A 15-year followup of the workers is currently underway, in which workers' medical records and lung function will be compared.
Peters noted that painters, particularly auto painters, are exposed to chemicals in paint called isosyanates, which are known to cause asthma. Machinists in the study may have been exposed to chemicals or contaminants in metal working fluids that could be a risk factor for developing both asthma and bronchitis, she said.