Increase in airway hyperresponsiveness among workers exposed to methylene diphenyldiisocyanate compared to workers exposed to toluene diisocyanate at a petrochemical plant in Korea

Abstract

Background The purpose of this study was to investigate the prevalence of airway hyperresponsiveness induced by methylene diphenyldiisocyanate (MDI) and toluene diisocyanate (TDI) at a petrochemical industry complex in Korea. Methods Questionnaires, allergic skin test, and nonspecific airway hyperresponsiveness (AHR) were studied in 64 exposed workers and 27 control subjects. Questionnaires included questions about symptoms of cough, wheezing, chest tightness, dyspnea, rhinorrhea, sneezing, itching, stuffiness, tearing, urticaria, sore throat, and exacerbating time. Methacholine challenge tests were done. Bronchial responsiveness (BRindex) defined as log (% fall in FEV1)/log (last concentration of methacholine +10). Results Prevalence of AHR (PC20 FEV1 < 16.0 mg/mL of methacholine) was higher in MDI‐exposed workers than in TDI‐exposed workers [4/20 (20%) vs. 2/42 (4.7%), P < 0.05]. Twenty‐three workers (36%) of all subjects had respiratory symptoms. MDI‐exposed workers, in comparison with control subjects, had higher BRindex (0.73 ± 0.04 vs. 0.62 ± 0.02, P < 0.05). Workers exposed to TDI or MDI who had respiratory symptoms (n = 23), in comparison to workers exposed to TDI or MDI without respiratory symptoms (n = 41), had significantly higher BRindex (0.82 ± 0.06 vs. 0.60 ± 0.02, P < 0.05). FEV1 was significantly negatively correlated with BRindex (r = −0.253, P < 0.05). BRindex was not correlated with atopy, smoking status, and exposure duration. Conclusions These findings suggest that workers exposed to MDI are at a higher risk of asthma in comparison with TDI‐exposed workers and control subjects at a petrochemical plant in Korea. Am. J. Ind. Med. 37:663–667, 2000. © 2000 Wiley‐Liss, Inc.

Polyisocyanates in occupational environments: A critical review of exposure limits and metrics

“…The exposure-response information in most epidemiological and clinical studies to date is too limited and the exposure settings and uses too variable to make any conclusions regarding relative toxicity differences between monomeric isocyanates, TDI, MDI, and HDI [Jang et al, 2000;Meredith et al, 2000;Ott et al, 2003]. However, all three likely cause isocyanate sensitization and asthma at approximately similar doses and specific challenge studies with TDI, MDI, and HDI use similar challenge protocols (typically 5-20 ppb for up to 2 hr) to induce an asthmatic response [Vandenplas et al, 1992a;Malo et al, 1999].…”

Synthesis of Optically Active and Thermally Stable Polyamides With Bulky Aromatic Side Chain in an Ionic Liquid (Tetrabutylammonium Bromide)

“…They have an important role as raw materials for the production of foams, paints, lacquers, inks, insulating materials, varnishes, rubber modifiers, and bonding and vulcanizing agents [9]. Several isocyanates are used in industry: 2,4-and 2,6-toluene diisocyanate (2,4-TDI1 2,6-TDI), 4,4 4 -diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), naphthalene diisocyanate (NDI), isophorone diisocyanate (IPDI) [10].…”

4,4′‐Methylene diphenyl diisocyanate (MDI) [101‐68‐8] and “polymeric” MDI (PMDI) [9016‐87‐9] [MAK Value Documentation, 2008]

“…This applies both to the attack-free interval and the asthma attack. Correspondingly, a higher incidence of non-specific airway reactions has been reported also in workers exposed to MDI (Jang et al 2000).…”