Asthma following inhalation accidents reported to the SWORD Project. Surveillance of Work-related and Occupational Respiratory Disease

Inhalation incidents and respiratory health: results from the European Community Respiratory Health Survey

BACKGROUND

Inhalation incidents are an important cause of acute respiratory symptoms, but little is known about how these incidents affect chronic respiratory health.

METHODS

We assessed reported inhalation incidents among 3,763 European Community Respiratory Health Survey (ECRHS) participants with and without cough, phlegm, asthma, wheezing or bronchial hyperresponsiveness. We then examined whether inhalation incidents during the 9-year ECRHS follow-up period were associated with a new onset of any of these respiratory outcomes among 2,809 participants who were free of all five outcomes at the time of the baseline ECRHS survey.

RESULTS

Inhalation incidents were reported by 5% of participants, with higher percentages reported among individuals with asthma-related outcomes at the time of the baseline survey. Among participants without symptoms at baseline, our analyses generated non-statistically significant elevated estimates of the risk of cough, phlegm, asthma and wheezing and a non-statistically significant inverse estimate of the risk of bronchial hyperresponsiveness among participants who reported an inhalation incident compared to those without such an event reported.

DISCUSSION

Our findings provide limited evidence of an association between inhalation incidents and asthma-related symptoms. These data could be affected by differences in the reporting of inhalation incidents according to symptom status at the time of the baseline survey; they should thus be interpreted with caution.

Reported incidence of occupational asthma in the United Kingdom, 1989-97

OBJECTIVES

To examine trends in estimated population based incidence of occupational asthma by age, sex, occupation, geographical region, and causal agents based on 9 years of the Surveillance of Work Related and Occupational Respiratory Disease (SWORD) data.

METHODS

In January 1989 the SWORD scheme for the surveillance of occupational respiratory disease was established in the United Kingdom to make good the lack of epidemiological information on the incidence of these diseases in the United Kingdom. Between 80% and 90% of chest and occupational physicians report voluntarily all new cases they see, on a monthly or random sampling basis. During the 9 years 1989-97, an estimated 25 674 new cases of occupational respiratory disease, including 7387 of occupational asthma, were reported. Suspected causal agents were classified into 44 categories and estimated annual incidences of asthma were calculated with denominators from the labour force survey.

RESULTS

Overall, a third of the suspected causes of asthma were organic, a third chemical, 6% metallic, and the rest miscellaneous, or in 8%, unknown. There was evidence of an increase since 1989 in cases due to latex, and possibly glutaraldehyde, and an apparent drop since 1991 in the proportion of cases attributed to isocyanates. Incidences were higher in men than women and the disparity was especially marked in the population aged 45 years or more in which rates for men were at least twice those for women. Average annual rates per million workers for 1992-7 ranged from 7 (95% confidence interval (95% CI) 5 to 9) for the lowest risk group of professional, clerical, and service workers to 1464 (95% CI 968 to 2173) for coach and other spray painters. Except for laboratory technicians, all other occupations with rates over 100 were concerned with manufacturing and processing that used chemicals, metals, and organic materials. Incidences were two to three times higher in the north and midlands than in East Anglia and the south. The introduction of a sampling scheme in 1992 doubled estimates of reported incidence of occupational asthma, but there was little evidence of other temporal changes.

CONCLUSIONS

The SWORD scheme has produced consistent estimates of the causes and incidence of occupational asthma as seen by chest and occupational physicians. It has allowed the epidemiology of occupational asthma in the population to be studied and high risk occupations to be identified. There is certainly more occupational asthma in the population than that which reaches specialists in occupational and chest medicine; therefore the incidence rates presented here are underestimates, but by how much remains unknown.