Date of Award

January 2014

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)



First Advisor

Carrie A. Redlich

Subject Area(s)

Occupational health


Background: Isocyanates are one of the most commonly reported causes of occupational asthma; however, the risks of developing isocyanate asthma in modern production facilities remain poorly defined. The purpose of the present investigation was to evaluate TDI exposure and respiratory health among an inception cohort of workers during their first year of employment at a new polyurethane foam production factory.

Methods: Forty-nine newly hired workers were evaluated pre-employment, 6-months, and 12-months post-employment through questionnaire, spirometry and TDI-specific serology. Airborne TDI levels were monitored by fixed-point air sampling and limited personal sampling. Qualitative surface SWYPE tests were performed to evaluate potential sources of skin exposure.

Results: Airborne TDI levels were low; over 90% of fixed-point air measurements were below the limit of detection (0.1 ppb). Over the first year of employment, 12 of the 49 original workers (24.5%) were lost to follow-up, no additional workers were enrolled, and seven of the 49 original workers (14.2%) developed either new asthma symptoms (N=3), TDI-specific IgG (N=1), new airflow obstruction (N=1) and/or a decline in FEV1 greater than or equal to 15% (N=3), findings that could indicate TDI-related health effects. The prevalence of current asthma symptoms was significantly higher in the workers lost to follow-up compared to those who completed the study (25% vs 2.7%; p=0.04).

Conclusions: The findings suggest possible early TDI-related health effects in a modern polyurethane production plant. These findings also highlight the need for further longitudinal evaluation of these workers and the challenges of studying workers at risk for isocyanate asthma.


This is an Open Access Thesis.

Open Access

This Article is Open Access