Chronic pulmonary function loss from exposure to toluene diisocyanate.

In 1972 a total of 112 workers exposed to toluene diisocyanate (TDI) were examined for acute pulmonary function changes during a work shift on the first day of the working week. A dose-response relationship was demonstrated for the acute effects of TDI in this population. The cohort was restudied in 1974 to determine whether there was excessive loss of pulmonary function, and if so, whether there was an exposure level below which this did not occur. The original cohort was reduced to 63 workers available for re-survey of which 57 could be assigned reliable personal exposure levels for the two-year study period. Pulmonary function measurements were made again before and after work on the first day of the working week. A total of 132 environmental samples were collected on this and previous occasions during the study period. The 57 workers were divided into three exposure subgroups (< 0-0015; 00020 0-0030; > 0 0035 ppm). Using the FEV1.0 as a measure of response, a dose-response relationship was observed. Only those in the lowest exposure subgroup showed normal two-year declines. The FEV1.0 of those in the highest exposure group fell 206 ml in two years (103 ml/year) which exceeds the expected value by threeto fourfold. The decrement of FEV1.0 in the middle exposure group was borderline (42 ml/year). These differences in FEV1.0 by exposure subgroup were not explained by age, months employed, smoking habits, or variables related to lung size. A significant association (r = 0-35, p < 0*005) between acute and chronic decrement in FEV1.0 was shown again. We conclude that chronic occupational exposure to TDI at 0 003 ppm or higher is unsafe. Polyurethane plastics have gained great popularity since the second world war for cushioning materials (mattresses, pillows, seat cushions and packing materials), insulation (thin-walled refrigerators and ovens) for soft toys, and surface coatings (varnishes and paints). Unfortunately, the increased use has been accompanied by pulmonary disease associated with exposure to the volatile isocyanate groups used to manufacture polyurethane. 1Supported in part by Grant No. 5ROlOH 00322, National Institutes for Occupational Safety and Health, Public Health Service, Department of Health, Education and Welfare and the Occupational and Environmental Health Center Grant No. ES 00002. Address for reprint requests: Dr D. H. Wegman, HSPH, 665 Huntington Avenue, Boston, Massachusetts 02115, USA. Received for publication 29 October 1976 Accepted for publication 19 January 1977 The production of polyurethane involves combining a polyol with a chemical containing two highly reactive isocyanate groups. It is during this mixing and foaming process that the isocyanates are released into the workroom atmosphere. Toluene diisocyanate (TDI) is the most commonly used isocyanate, and because of its volatility it is also the most hazardous. The clinical features of isocyanate-associated illness were summarised by Brugsch and Elkins (1963). Eye, nose and throat irritation are usually the first clinical manifestations. Dry cough with chest pain or tightness often follow. Because the cough or wheeze are characteristically worse in the evening or at night, the patient or doctor may not recognise its occupational aetiology. Rhonchi or coarse rales are frequently present. Insome workers thecharacteristic pattern of bronchial asthma is the initial manifestation; in others it develops late. Chest radiographs taken during the acute stage are usually 196 group.bmj.com on October 19, 2017 Published by http://oem.bmj.com/ Downloaded from