Nurses and cleaners among highest risk groups for developing occupational asthma.
Nurses are more than twice as likely as the general population to develop occupational asthma, conclude authors of an Article published in this week's edition of the Lancet.
Dr Manolis Kogevinas, Centre for Research in Environmental Epidemiology, Municipal Institute of Medical Research, Barcelona, Spain and colleagues also found that cleaners were at a 71% higher risk of developing occupational-related asthma compared to the general public, and that workplace conditions could be responsible for up to 25% of new asthma cases in industrialised countries.
The researchers studied 6837 people from 13 countries who had previously taken part in the European Community Respiratory Health Survey (1990-95), who had not reported any history or symptoms of asthma at the time of the study. Each was then followed-up for around nine years, tested for asthma and asked to fill in a questionnaire on symptoms. Possible exposures to asthma-causing substances were calculated using an "asthma-specific job exposure matrix" with additional expert judgement. Computer-modelling was then used to calculate the risk of new-onset asthma adjusted for age, sex, smoking and study centre.
A significant excess asthma risk (60%) was seen after exposure to substances known to cause occupational asthma, while risks were highest for asthma defined by bronchial hyper-activity in addition to symptoms (140% increased risk). The worst occupations for excess risk were: printing (137%), nursing (122%), woodworking (122%), agriculture/forestry (85%), and cleaning (71%). Specific incidents through the course of an individual's life which exposed them to asthma-causing irritants, such as fire, mixing cleaning products, or chemical spillages, led to them being over three-times more likely than the general public to develop new-onset asthma.
The authors believe there could be a number of reasons for the increased risk to nurses. They say: "Nurses could be exposed to sensitising substances, respiratory allergens, and irritants including sterilisers and disinfectants such as glutaraldehyde or bleach." They add that although in the early 1990s nurses' exposure to latex may have increased as gloves were used more often than before, the exposure probably declined as the amount of latex in these products was cut down over time.
The authors conclude: "Findings from this large international study suggest that the frequency of [occupational asthma] is systematically underestimated. The heightened asthma risk after inhalation accidents suggests that workers having such accidents should be monitored closely. Reduction of exposure, and early and complete identification of workers with symptoms suggestive of asthma, would help prevent the disease and effectively manage workers who develop occupational asthma."
In an accompanying Comment, Drs Jean-Luc Malo and Denyse Gautrin, Sacra-Coeur Hospital, Montreal, Canada, say that Kogevinas and colleagues' study "is a welcome contribution that provides a better estimate of the frequency of asthma attributable to occupational agents."