New methodology for specific inhalation challenges with occupational agents.
BACKGROUND
Inhalation challenges are used for diagnosing occupational asthma (OA). The initial methodology consisted of a "realistic" exposure without monitoring nor controlling exposure. Our aim was to design an equipment, called the GenaSIC, that allows the generation of various agents regardless of the formulation and to assess the feasibility of its use in patients investigated for OA.


RESULTS
GenaSIC can generate lactose, flour, malt, isocyanates, formaldehyde and N-butyl acetate with precise and fairly stable concentrations. Using N-butyl-acetate as a control agent and real time measurement, we show that normal breathing has a negligible effect on the concentration. We exposed forty-four different subjects to a control agent and/or to a suspected occupational agent. Nineteen of the subjects were only exposed to N-butyl acetate as a control agent without experiencing any significant irritant effect (no significant changes in spirometry thereafter). Eight subjects who were exposed to both N-butyl acetate and formaldehyde did not show significant reactions. Seven subjects were exposed to dry particles (flour in six instances, malt in the other) and five showed immediate asthmatic reactions which changes in FEV1 from 20% to a maximum of 28%. Finally, ten subjects were exposed to isocyanates, four of whom showed a positive reaction, including one subject with immediate maximum changes in FEV1 of 22%.


CONCLUSIONS
GenaSIC offers the possibility of reliable and safe exposures to dry particles, formaldehyde and isocyanates in the investigation of OA.
Department of Chest Medicine, Sacré-Coeur Hospital, Montreal, Canada.
Simon
S
Caron
Jean-Christian
JC
Boileau
Jean-Luc
JL
Malo
Simon
S
Leblond
D000328:Adult; D000395:Air Pollutants, Occupational / Q000009:adverse effects*; D001249:Asthma / Q000139:chemically induced / Q000175:diagnosis* / Q000503:physiopathology; D001985:Bronchial Provocation Tests / Q000295:instrumentation*; D004867:Equipment Design; D005240:Feasibility Studies; D005541:Forced Expiratory Volume; D006801:Humans; D019570:Inhalation Exposure; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000139:chemically induced / Q000175:diagnosis* / Q000503:physiopathology; D016272:Occupational Health; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013147:Spirometry; D013997:Time Factors
D000395:Air Pollutants, Occupational