Biological monitoring of TDI-derived amines in polyurethane foam production

Abstract

Background: Toluene diisocyanate (TDI) is used in industry in the production of flexible polyurethane foam, commonly a mixture of the 2,4- and 2,6- isomers. The production process may lead to exposure to diisocyanates which are associated with respiratory disease. A method has been available for the determination of TDI biomarkers in urine for some years.

Aims: To explore the usefulness of urinary toluenediamine (uTDA) in assessing whether dermal absorption of diisocyanates makes a significant contribution to a worker's total exposure.

Methods: Twenty-six workers took part in the study. Thirteen workers whose duties brought them into physical contact with uncured polyurethane foam during their shift (handlers) were compared to a control group of 13 workers in the same block plant environment had no physical contact with uncured foam on the day that sampling took place (non-handlers). Creatinine-adjusted uTDA levels in the two groups were compared across a work shift.

Results: Both groups of workers were exposed to similar levels of airborne TDI. Ten handlers were found to have TDA in post-shift urine samples above detection limits compared with two non-handlers (P < 0.05). No clear relationship was found between the level of airborne TDI exposure and post-shift uTDA.

Conclusions: uTDA provides a useful indication of the contribution which skin absorption makes to total TDI exposure. The results suggest that skin protection when handling uncured polyurethane foam may not receive sufficient consideration.