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In their recent short report, O'Connor et al1 describe a case of occupational asthma due to the enzymes phytase and β-glucanase. Their patient experienced asthma-like symptoms at work (wheezing and cough), had positive skin prick tests and specific IgE to both enzymes (by radioallergosorbent test), and reacted to both materials in separate inhalation challenge tests. None of 22 other employees in the same factory were reported to have experienced respiratory symptoms at work.1
In a German language paper presented at the 38th Annual Meeting of the German Association of Occupational and Environmental Medicine in 1998,2 we reported findings of a systematic clinical investigation of 49 research and development employees working with the enzymes phytase and xylanase. This investigation was undertaken after detecting airway sensitisation to dusts containing phytase in two analytical laboratory employees.
Forty nine employees with potential contact to the enzyme completed a questionnaire and underwent physical examination and lung function testing. Among 32 employees with findings of conjunctivitis, rhinitis, or bronchitis further immunological tests were undertaken on a voluntary basis (skin prick test, n=17; specific IgE by enzyme allergosorbent test (EAST), n=31). Also, nasal provocation challenge tests were performed in 13 employees, including all 11 with a positive skin prick test to phytase. Nine of these employees had a positive specific IgE test to phytase as well. All 11 had a positive nasal challenge response to phytase. The positive response rate was 62.5% among eight employees considered to have the highest potential exposure. Based on this investigation, it was concluded that phytase has a high sensitising potency. Our assessment of this is consistent with that of O'Connor et al and Doekes et al.1,3
After implementation of extensive control measures to prevent enzyme exposure in this research and development facility, all employees now report being free of work related respiratory symptoms. This favourable experience agrees with the hypothesis that enzyme related asthma can be avoided by implementing best practice procedures for health surveillance and environmental control when working with enzymes.4