Toxicologie environnementale et analytique

Validation of a New Paper-Tape Monitor for the Quasi-Continuous Determination of Airborne Di-isocyanate Concentrations

Abstract

Christian Monsé, Jens-Uwe Hahn, Heinz Assenmacher-Maiworm, Gerd Keßler, Jürgen Bünger, Thomas Brüning and Rolf Merget

Occupational exposures to diisocyanates may cause allergic asthma. Inhalation challenges are the most important tool for the diagnosis of occupational asthma due to diisocyanates. Various diisocyanate atmospheres can be generated at IPA. A multi-steps exposure protocol is used, the dosage is constantly monitored and adjusted if necessary. The quasi-online monitoring of concentrations of airborne diisocyanates in the laboratory is done with a paper-tape monitor, which is widely used in laboratories that perform inhalation challenges worldwide, but also for monitoring of threshold limits at workplaces. The analyzer MDA 7100 (Zellweger Analytics, Inc., Lincolnshire, USA) is no longer supported by the producer. It was replaced by the successor model Single Point Monitor (Honeywell Analytics, Inc., Lincolnshire, USA), but comparative measurements are not available. It was the aim of this study to compare both paper-tape monitors with a discontinuous standard procedure. Comparative measurements between the two paper-tape monitors showed that the newer model yielded lower concentrations than the old device. Both paper-tape monitors yielded lower values than the reference method at concentrations > 10 ppb. The old monitor detected 68%, the new device 38% of the average concentration of the standard method at 36.7 ppb. We conclude that the differences between the measurements with the new paper-tape monitor and the standard method are important above concentrations of about 10 ppb. For monitoring of diisocyanate concentrations < 5 ppb at workplaces, the deviations are negligible.