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.