Occupational asthma caused by isocyanates : Patterns of asthmatic reactions to increasing day-to-day doses.
Inhalation challenges to isocyanates are conducted in specialized centers to confirm occupational asthma.
The pattern of asthmatic reactions due to consecutively increasing daily doses of isocyanates is unknown.
We conducted a study involving 24 subjects who had undergone specific inhalation challenges to isocyanates (toluene diisocyanate [TDI], n=8 ; hexamethylene diisocyanate [HDI], n=10 ; and methylene diisocyanate [MDI], n=6) on three or more consecutive days.
Challenge tests were given through a closed-circuit apparatus (n=12) or in small cubicles (n=12), allowing assessment of the total inhaled dose (concentration x duration).
The pattern of asthmatic reactions was described.
In addition, dose-response curves were analyzed and tested for their linear and quadratic trends.
Four patterns of response were observed :
(1) linear (n=10) ;
(2) minimal effect followed by a brisk change (n=7) ;
(3) significant change followed by tachyphylaxis or a plateau (n=4) ;
(4) biphasic (i.e., significant change followed by a reduction in the effect and significant change on the last day of exposure [n=3]). Subjects with a linear dose-response pattern had been exposed to isocyanates at work for a significantly shorter interval (7.2 ± 6.7 yr) than subjects with a nonlinear pattern (20.0 ± 13.1 yr).
An analysis of variance covering a 3-d period for all subjects showed a significant linear model for the response (p<0.0001) ; there was no quadratic trend. (...)
Mots-clés Pascal : Asthme, Allergie, Exposition professionnelle, Isocyanate organique, Dose croissante, Réaction, Exploration, Homme, Appareil respiratoire pathologie, Bronchopneumopathie obstructive, Immunopathologie, Médecine travail
Mots-clés Pascal anglais : Asthma, Allergy, Occupational exposure, Organic isocyanate, Increasing dose, Reaction, Exploration, Human, Respiratory disease, Obstructive pulmonary disease, Immunopathology, Occupational medicine
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Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 99-0353238
Code Inist : 002B03L06. Création : 14/12/1999.