Date of Award

January 2013

Document Type

Open Access Thesis

Degree Name

Master of Public Health (MPH)


School of Public Health

First Advisor

Meredith H. Stowe



Diisocyanates are sensitizing agents that are used in many industries in the production of polyurethane foams, coatings and other products. Methylene diphenyl diisocyanate (MDI) exposure can occur through dermal and inhalation routes resulting in sensitization and leading to isocyanate asthma. MDI-specific IgG (MDI-IgG) bio-monitoring has been proposed to be used as a predictor of exposure.


A prospective longitudinal study was used to assess annual MDI- IgG serum markers in 223 workers in a fabric-coating company. Kaplan Meir Survival Analysis determined whether there was a difference in seroconversion based on exposure level. A Cox proportional hazard model was used to see if covariates such as total IgE level, cough, rash, allergies, and smoking contributed to time to change. Data from 2012 and 2013 were used to compare MDI-IgG level after the implementation of new safety measures.


MDI- IgG seroconversion from negative to positive was statistically significant for a difference in the survival curves (p= 0.0076) with respect to job classification. No statistical difference was found among workers for time to seroconversion from MDI-specific IgG positive to negative (p= 0.9232). A non-parametric sign test was used to evaluate the paired serology results for individuals between 2012 and 2013, indicating a significant decrease in MDI-specific IgG levels (p=0.0001).


There is a significant correlation between job classification and time to positive seroconversion. Biomonitoring may track and trend changes that reflect worker exposures. Data suggest that safety interventions could play an important role in preventing MDI asthma and ensure worker safety.


This is an Open Access Thesis.

Open Access

This Article is Open Access