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

Background Work-related asthma is a leading cause of occupational respirato ry illness. Methods Work-related asthma was studied in California over a 36-month perio d, from March 1, 1993 to February 29, 1996. The surveillance system identif ied cases from Doctor's First Reports (DFRs), a mandated physician reportin g system. Structured follow-up telephone interviews of DFR asthma cases wer e conducted to collect work history, exposure, and medical information. Sta tewide employment data was used to calculate disease rates among industry g roups. Results Based on 945 cases of work-related asthma, the average annual repor ting rate for work-related asthma in California was 25/million workers. We estimate that the actual rare is 78/million, adjusted for likely underrepor ting. Janitors and cleaners (625/million) and firefighters (300/million) ha d the highest reporting rates of work-related asthma. Half of all work-rela ted asthma cases were associated with agents not known to be allergens. Conclusions A greater proportion of work-related asthma associated with irr itant exposures was identified than has previously been reported. The surve illance data provide a very conservative estimate of the incidence of work- related asthma. Am. J. Ind. Med. 39:72-83, 2001. (C) 2001 Wiley-Liss, Inc.