Hepatic Health Hazards of Occupational Exposure
to the Products of Polyurethane Thermal Degradation

Amal Saad1, Mohga S. Abd-Alla2, El-Sayed A. El-Desokky1, Hayat M. Sharada2, and Mohamed M. Fouad1

1 Department of Environmental and Occupational Medicine, National Research Center, Dokki, Cairo, Egypt
2 Department of Biochemistry, Faculty of Science, Helwan University, Helwan, Egypt

Corresponding author: Dr. Amal Saad
    Department of Environmental and Occupational Medicine
    National Research Center
    Dokki, Cairo, Egypt
    Fax number: Fax: 202-74-82616

CEJOEM 2004, Vol.10. No.4.: 319–332


Key words:
Polyurethane thermal degradation products, specific IgE to MDI, sIgE to TDI, HCV, smoking habits, AFP and liver functions


Abstract:
In the industry of flexible packing, polyurethane sheets are thermally liquefied and used as glue. The products of polyurethane thermal degradation have been evidenced to be hazardous to the liver. The aim of the present study was to evaluate the hepatic health hazards of the occupational exposure to these products and to discuss the role of confounding factors. Forty-two workers, occupationally exposed to polyurethane thermal degradation products were compared to 44 control subjects matched for age and socioeconomic status and having the same habits. Personal, occupational and medical questionnaires were filled in. Full clinical examinations were done for all subjects. Hepatic functions, alpha-fetoprotein (AFP), and serological analysis for hepatitis markers were also done. Estimation of the titers of the specific IgE to diphenyl methane diisocyanate (MDI) and to toluene diioscyanate (TDI) were done for the hepatitis C virus (HCV) seronegative exposed workers and their controls. Statistical analysis proved that the clinical manifestations of chronic hepatic toxicity were not significantly detected among the exposed workers. In the exposed workers the activity of liver enzymes was significantly elevated compared to the controls. The level of gamma glutamyl transferase (γGT) of HCV seropositive workers was significantly higher than that of seronegative workers. Total protein, albumin, and albumin/globulin (A/G) ratio of the exposed workers were significantly decreased compared to their controls. In HCV-seropositive exposed workers, the level of AFP was significantly higher than both in the HCV-seronegative workers and controls. The liver functions of the workers, whether smokers or non-smokers, significantly differed from their controls. Simple factorial analysis revealed that synergistic effects only took place in the γGT activity between hepatitis C and/or smoking habits and the exposure to polyurethane thermal degradation products. However, hepato-carcinogenic effect of these products remained questionable, as AFP was significantly elevated only among the HCV-seropositive workers. Cumulative hepatic toxic effect of occupational exposure to the products of polyurethane thermal degradation was proved after exclusion of confounding factors. This was proved as in the exposed group the activity of liver enzymes positively correlated with the duration of exposure, while total protein, albumin, and the A/G ratio negatively correlated with it.


Received: 30 August 2004
Accepted: 22 February 2005

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