Physician reports of work-related asthma in California, 1993-1996.

BACKGROUND

Work-related asthma is a leading cause of occupational respiratory illness.

METHODS

Work-related asthma was studied in California over a 36-month period, from March 1, 1993 to February 29, 1996. The surveillance system identified cases from Doctor's First Reports (DFRs), a mandated physician reporting system. Structured follow-up telephone interviews of DFR asthma cases were conducted to collect work history, exposure, and medical information. Statewide employment data was used to calculate disease rates among industry groups.

RESULTS

Based on 945 cases of work-related asthma, the average annual reporting rate for work-related asthma in California was 25/million workers. We estimate that the actual rate is 78/million, adjusted for likely underreporting. Janitors and cleaners (625/million) and firefighters (300/million) had the highest reporting rates of work-related asthma. Half of all work-related asthma cases were associated with agents not known to be allergens.

CONCLUSIONS

A greater proportion of work-related asthma associated with irritant exposures was identified than has previously been reported. The surveillance data provide a very conservative estimate of the incidence of work-related asthma.