Occupational asthma in TDI-exposed workers in Korea: prevalence and immunogical study

초록

Objectives: TDI is known to be the most common cause of occupational asthma (OA) in Korea, but improved working environment and approach to occupational medicine may decline the development of OA in workers with TDI-exposed jobs. This study was carried out to estimate the prevalence of TDI-induced asthma, and to evaluate the clinical significance of specific IgE (sIgE) and IgG (sIgG) antibodies to TDI-HSA conjugate in TDI exposed workers. Methods: Medical questionnaire, and pulmonary function tests were performed in 170 workers with job of direct exposure to TDI. After screening, workers with suspected TDI-induced OA were selected for methacholine and TDI bronchial provocation tests (BPTs). Serum sIgE and sIgG to TDI-HSA conjugate were measured by enzyme linked immunosorbent assay. Results: Eleven (6.9%) of 170 TDI-exposed workers complained symptoms of OA, and 7 (4.1%) of them showed positive responses to methacholine BPTs. One worker with spray-painting job was confirmed as having TDI-induced asthma by showing a positive response to TDI BPTs. There was no significant difference in prevalence of sIgE and sIgG antibodies to TDI-HSA conjugate between symptomatic and asymptomatic workers. Conclusions: The prevalence of TDI-induced OA was 0.58% in current working environment in Korea, and was lower than previously reported prevalence rates (2-20%). Healthy worker effect, improved workplace environment and lower level of exposure to TDI compared to the past might contribute this low rate of OA prevalence in workers with TDI exposure. Further prospective studies will be required to clarify the clinical significance of specific antibody response to TDI.