Chest
Clinical InvestigationsBronchial Hyperresponsiveness and Toluene Diisocyanate: Long-term Change in Sensitized Asthmatic Subjects
Section snippets
Subjects
We studied 16 subjects with TDI-induced asthma over a followup period of 48 months (range, 18 to 73 months), during which nonspecific bronchial responsiveness to methacholine was measured at least 3 times (mean, 6.5 ± 2.5).
The diagnosis of TDI-induced asthma was assessed when the subjects were still at work, on the basis of the following findings: (a) symptoms of bronchoconstriction related to the occupational exposure (spray painting in the furniture industry); (b) presence of NSBH to
RESULTS
At diagnosis, baseline FEV1 of the 16 patients was 81.7 ± 12.4 percent (Table 1). The duration of exposure to TDI in the furniture industry was 20.7 ± 8.9 years, and the duration of symptoms before diagnosis was 3.8 ± 4.1 years (range, 0.5 to 15 years). However, 11 of 16 subjects referred had symptoms for 3 or fewer years. Eight out of 16 subjects were nonsmokers, 6 were ex-smokers, and 2 were current smokers.
Immediately after diagnosis, nine subjects completely stopped working. The remaining
DISCUSSION
Our study shows that cessation of occupational exposure to TDI leads to recovery of specific and nonspecific bronchial hyperresponsiveness only in a small percentage of cases, and that such a recovery requires a long time to develop. Our data also show that NSBH to methacholine can persist even after specific responsiveness to TDI discontinues. After work cessation, NSBH persisted in most patients despite a mild improvement in asthmatic symptoms and a reduced need for drug therapy.
The analysis
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Inhalation challenges with occupational agents: Threshold duration of exposure
2013, Respiratory MedicineCitation Excerpt :Disconcertingly, the interval of time elapsed since the last work exposure did not affect directly the TD20%FEV1. Several studies that involved re-challenging subjects with OA at variable intervals after the initial SIC documented that the specific bronchial reactivity to occupational agents may decrease after cessation of the sensitizing agent,4–6,8 with the exception of a study involving platinum salts [Merget, 1994 #477}. Using the same concentrations of the agents as those generated during the initial SIC, Lemière and co-workers found that the duration of exposure, and consequently the total dose, required for inducing a positive SIC response significantly increased (∼3-fold on average) in subjects with OA due to various agents who were re-challenged two years after removal from exposure.8
Avoidance therapy in reactive dye-induced occupational asthma: Long-term follow-up
2006, Annals of Allergy, Asthma and ImmunologyWhat can we learn about asthma from studying occupational asthma?
2003, Annals of Allergy, Asthma and ImmunologyPersistence of bronchial reactivity to occupational agents after removal from exposure and identification of associated factors
2003, Annals of Allergy, Asthma and ImmunologyImpairment in workers with isocyanate-induced occupational asthma and removed from exposure in the province of Québec between 1985 and 2002
2006, Journal of Occupational and Environmental Medicine
Supported in part by grants 87.00182.04 and 88.00593.04 from the Italian National Research Council and by a grant from the Italian Ministry of Education.
Manuscript received January 13; revision accepted August 10.