Diagnosis and prevention of diseases induced by isocyanate

Abstract

Isocyanates are among the most frequent causes of occupational asthma in industrialized countries. Early diagnosis of diisocyanate asthma followed by prompt termination of chemical exposure can prevent chronic morbidity due to persistent asthma. Chronic exposure to isocyanates also induces hypersensitivity pneumonitis (HP). The accurate diagnosis of diisocynate asthma requires a systematic approach that combines information obtained from the occupational history, immunologic tests and physiologic studies. The prevention of health problems from toluene diisocyanate (TDI), 4,4'-methylenediphenyl diisocyanate (MDI) and 1,6'-hexamethylene diisocyanate (HDI) is essential for all those handling the chemicals. Regulatory exposure limits should be observed. However, wheezing, coughing or even asthmatic attacks may occur after exposure much below the regulatory exposure limits especially in sensitive individuals. Preventing or minimizing exposure is of prime importance and should be supported by the installation of engineering controls, by education of the workforce, by regular monitoring of the workplace exposure and by medical surveillance. To prevent such asthma it is suggested that workers should be tested airway sensitivity and should avoid working in areas that have dust containing specific-IgE. Such tests must be periodically performed after working. Symptoms induced by isocyanate need earlier discover and early isolation of the associated individuals.

Lung disorders induced by respirable organic chemicals

“…Typical symptoms with isocyanates include work related dyspnea, malaise, and fever several hours after work. 15 The prognosis of HP is reported to be good in most (but not all) cases, provided that exposure ceases. There are no reports on the prevalence of hypersensitivity pneumonitis in workers handling isocyanates in Japan as far as we know, but the prevalence of hypersensitivity pneumonitis in workers handling isocyanates in cross-sectional surveys in Canada and Germany was reported to be 0.9%-4.7%.…”

Enfermedades del intersticio pulmonar de causa laboral. Parte II

“…aconsejan realizar, además, controles serológicos de IgE específica para poder lograr una detección precoz y proceder en consecuencia. 79…”

Synthesis of Unsymmetrical Urea Derivatives via Cu‐Catalyzed Reaction of Acylazide and Secondary Amine

“…[29,30] These methodologies need toxic solvent (DMF, DMSO and halogenated solvent), extended reaction time and work up procedure. [31][32][33][34] Isocyanates are carcinogenic in nature, [35,36] highly reactive with water and can cause eyes itching, [35,36] they have storage problem and for the synthesis require phosgene and triphosgene toxic reagent. [26][27][28] Alternatively, Kokotos and co-workers developed one-pot synthesis of urea (Scheme 1b) in this methodology Boc-protected amines transformed into urea by utilizing 2-chloropyridine and trifluoromethanesulfonyl anhydride for in situ isocyanate generation.…”