Cardiorespiratory Effects of Occupational Exposure to Polyurethane Thermal Degradation Products

Hesham M. Aziz and Amal Saad

Department of Environmental and Occupational Medicine, National Research Center, Dokki, Cairo, Egypt

Corresponding author: Dr. Amal Saad
    Department of Environmental and Occupational Medicine
    National Research Center
    Tahrir Street
    Dokki, Cairo, Egypt
    Fax number: 202-33-70931
    E-mail: amel_h3@yahoo.com

CEJOEM 2005, Vol.11. No.3.: 169–177

Key words:
Polyurethane thermal degradation products, ventilatory function tests, electrocardiogram, specific IgE to MDI, and specific IgE to TDI

Abbreviations:
FEV1
FVC
HDI
MDI		 = forced expiration volume in 1 s1
= forced vital capacity
= hexamethylene-diphenyl diisocyanate
= methylene-diphenyl diisocyanate		 PEF1
RVH
sIgE
TDI		 = peek expiratory flow1
= right ventricular hypertrophy
= specific IgE
= toluene diisocyanate

Abstract:
Polyurethane thermal degradation produces a wide variety of hazardous compounds including diisocyanates, such as methylene-diphenyl diisocyanate (MDI), toluene diisocyanate (TDI), and hexamethylene-diphenyl diisocyanate (HDI), in addition to carbon monoxide, carbon dioxide, hydrogen cyanide, oxides of nitrogen, and other hazardous pyrolysis products. These components proved to have hazardous effects on the respiratory system. The aim of the present study was to evaluate the cardiorespiratory effects of exposure to the products of polyurethane thermal degradation in the workers of packing industry using polyurethane sheets as a resin. Seventy-six workers occupationally exposed to polyurethane thermal degradation products were compared to 72 control subjects of matched age, socioeconomic status, and habits. Personal, occupational, and medical questionnaires were filled in. Full clinical examination, ventilatory function tests, electrocardiogram (ECG), and determination of specific IgE (sIgE) for MDI and for TDI were done for all subjects. Statistical analysis revealed significant decline in the ventilatory functions and significant elevation in the incidence of ECG abnormalities of the exposed group compared to their controls. Right ventricular hypertrophy (RVH) seemed to be higher in the exposed group (5.3%) than among the controls (1.4%). In the exposed workers with RVH, forced expiration volume in one second (FEV1), and forced vital capacity (FVC) displayed significantly lower levels than in the workers without RVH. An inverse correlation was detected between peek expiratory flow (PEF) and the sIgE for MDI and for TDI. There were no significant relations between sIgE for MDI and for TDI, on the one hand, and the ventilatory functions (FEV1 and FVC) and ECG abnormalities, on the other hand. In conclusion, the present study has shown that chronic exposure to the products of polyurethane thermal degradation may decline the ventilatory function and cause ECG abnormalities. The ECG abnormalities, mainly RVH, may result in chronic obstructive pulmonary defects. The present results concluded also that specific IgE for MDI and for TDI could be considered as biomarkers for exposure to polyurethane thermal degradation products, but not as an indicator of the level of health damage.

Received: 24 August 2005
Accepted: 18 October 2005
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