Intestinal obstruction in acute inhalational toluene 2,4-diisocyanate gas toxicity

The isocyanates are widely used as precursors of polyurethane products, as well as carbamate insecticides. Toluene 2,4-diisocyanate (TDI) is one of the most important commercially used isocyanates. Humans may be exposed to TDI by inhalation, ingestion, dermal and eye contact. TDI is a powerful irritant to the mucosal membranes of the gastrointestinal and respiratory tracts, eyes and the skin. Pulmonary manifestations, especially occupational asthma, are the predominant manifestations after TDI toxicity. Herein, we present intestinal obstruction as an extraordinary manifestation of acute TDI toxicity after occupational exposure. TDI toxicity may cause intestinal obstruction.

Neuropathy in an artist exposed to organic solvents in paints: a case study

A 61-year-old artist in Israel had been painting for 30 years in his home studio. He had been healthy until he reached the age of 59.5 years, at which time he began complaining of weakness and paresthesia in both hands and legs. He also complained that he had difficulty concentrating, and his memory was impaired. His work was unusual in that he painted large posters (i.e., 2 x 3 m) with different mixtures of organic solvents, including toluene, xylene, benzene, methyl ethyl ketone, toluene diisocyanate, acetone, and thinner. He did not use any protective gloves and did not wear a mask. He was evaluated with several methods and was diagnosed as having peripheral and central neuropathy, including ototoxic hearing loss as a result of long exposures to organic solvents. The authors were unable to find any similar case report in the literature.

[Pathogenesis of tolylene diisocyanate intoxication]

Experimental and clinical investigations to evaluate immunity, lipid peroxidation (LPO), and antioxidative defense (AOD) under the action of tolylene diisocyanate at the level of MAC and 10 MAC were conducted for further studies of the agent's pathogenetic mechanisms. The experimental investigations showed the predominant activation of cellular and humoral immunities, as well as the suppression of nonspecific defence at 10 MAC, enhanced LPO, and phasic changes in AOD. Most profound immunological changes were observed in those having as long as 5 years of length of service.

Toluene diisocyanate exposure in a glove manufacturing plant

CASE REPORT

An accidental exposure due to reuse of containers of toluene diisocyanate to transport nontoxic substances and subsequent occupational toxic exposure caused illness among forty workers in a glove manufacturing plant. Examination and investigation of the patients and factory site inspection were carried out. Toluene diisocyanate-contaminated latex was examined by the infrared spectroscopy. Thirty-two of forty patients had muscle pain and seven had elevated creatine phosphokinase activity. These features have not been reported previously as components of toluene diisocyanate toxicity and their underlying causation remains speculative.

Seroimmunological characteristics of Korean workers exposed to toluene diisocyanate

Since type I allergy caused by specific IgE antibodies may play principal roles and IgG antibody-mediated reactions have been thought to be involved in some parts of the pathogenesis, this study was performed to investigate the role of IgE- or IgG-mediated hypersensitivity reactions in development of toluene diisocyanate (TDI) asthma in Korean workers. For 81 TDI spray painters, self-administrative questionnaires and direct interviews on respiratory symptoms, chest auscultation, and measurements of forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEV1.0) were performed. The TDI concentration in their working environments was measured. Levels of serum IgE and IgG specific to TDI were estimated by radioallergosorbent test (RAST) and ELISA using p-tolyl isocyanate-human serum albumin (TMI-HSA) as the antigen. When sputum, cough, and dyspnea aggravated by work or wheezing existed, when FVC or FEV1.0 was less than 80% of the normal reference value, or when IgE RAST for TDI was positive, the peak expiratory flow rate (PEFR) was recorded four times per day for over 2 weeks. If decrease of PEFR was over 20% of baseline PEFR and changing pattern of PEFR was closely related to workshift in time, then a diagnosis of TDI asthma was made. Changing patterns of PEFR of 8 (9.9%) workers corresponded to the diagnostic criteria of TDI-related occupational asthma. Levels of the specific IgE were increased in 9 (11.1%) of the 81 subject workers and in 3 (37.5%) of the 8 PEFR-positive workers. Levels of the specific IgG were increased in 9 (11.1%) workers, and in only 1 (12.5%) of the asthmatics sensitive to TDI. Neither elevated TDI-specific IgE levels nor PEFR test positivities were associated with increased IgG levels. The mean titer of the PEFR-test-positive workers was slightly lower than that of the PEFR-negative workers and that of the IgE RAST-positive workers lower than that of the test-negative workers, but there was no statistical significance. These results suggest that IgG is not deeply involved in the pathogenesis of TDI-induced occupational asthma in Korean workers.

[Cohort studies of effects of long-term toluene diisocyanate (TDI) exposure on pulmonary function]

Toluene diisocyanates (C6H3CH3 (NCO)2, TDIs) are synthetic low molecular-weight organic chemicals with two highly reactive isocyanate groups (-NCO). Exposure to TDI can cause irritation of the eyes, nose, and upper and lower respiratory tract, asthma-like responses, sensitive pneumonitis, and obstructive pulmonary function loss. In this paper, the exposure-effect relationships between long-term TDI exposure and its effect on pulmonary function are summarized by evaluating the results of cohort studies, including 2 cohort studies conducted by the author's research team, which were specially devoted to the exposure-effect relationships and were published at the end of 1992. By assessing the exposure-effect relationships, the current occupational exposure limit of TDI in Japan is discussed and a framework for the health checks on TDI-exposed workers is proposed.

Absence of respiratory effects in subjects exposed to low concentrations of TDI and MDI

One hundred seven subjects from a polyurethane plastic manufacturing plant have been followed over a five-year period with measurements of forced expiratory volume in 1 s (FEV1), and questionnaires on respiratory symptoms and smoking habits. Environmental concentrations of toluene diisocyanate and diphenyl methyl diisocyanate were extensively monitored to provide accurate estimates of the upper-limits of exposure of the subjects. Current mean levels of FEV1 in this population were higher than those predicted for healthy subjects. The five-year change in FEV1 did not exceed that expected from aging. No acute change in FEV1 could be demonstrated over the course of a Monday either before or after a two-week vacation. No improvement in ventilatory function was observed over the vacation period. The presence of cough or sputum was related to smoking but was not related to isocyanate exposure. The results indicate that exposure of workers to extremely low levels of isocyanates (time-weighted average concentrations of the order of 0.001 parts per million [ppm]) is not associated with chronic respiratory symptoms or effects on ventilatory capacity. The results suggest that isocyanates can be controlled to the point of eliminating effects as measured by these techniques.

Warfarin binding to plasma of workers exposed to toluene diisocyanate

The extent of [14]C-warfarin binding to plasma proteins was evaluated in a group of normal, healthy volunteers and in two groups of individuals occupationally exposed to toluene diisocyanate (TDI). Plasma binding was assessed by ultrafiltration after the addition of racemic [14]C-warfarin to a final concentration of 0.8 microgram/ml. Chronic occupational exposure to TDI did not affect the extent of warfarin binding since warfarin free fractions (normalized to an albumin concentration of 4.5 g/dl) were 1.09 +/- 0.23 (mean +/- SD), 0.98 +/- 0.19, and 0.97 +/- 0.15 for controls and the two groups of TDI-exposed individuals, respectively.

Neurological complications after a single severe exposure to toluene di-isocyanate

A total of 23 men complained of neurological symptoms after a single severe exposure to toluene di-isocyanate. Effects of exposure were immediate in five men and consisted of euphoria, ataxia, and loss of consciousness. These men and nine others complained of headache, difficulty in concentration, poor memory, and confusion during the next three weeks. Four years later it was found that nine further men had experienced symptoms that they had not been aware of at three weeks. In all, 13 men still complained of poor memory, personality change, irritability, or depression after four years. Psychometric testing showed a selective defect for relatively long-term recall in those with persistent symptoms at four years.

Accidental exposure to isocyanate fumes in a group of firemen

A total of 35 firemen involved in fighting a fire in a factory in which polyurethane foam was made were exposed to fumes of toluene di-isocyanate from two large storage tanks which were damaged during the fire, resulting in massive spillage. Most of the men experienced symptoms during the fire or during the three weeks after it. The symptoms were mainly gastrointestinal, respiratory, or neurological. Altogether 15 men described gastrointestinal symptoms which subsided within two days of onset. Respiratory symptoms were described by 31 men and were most pronounced during the three days after the fire, thereafter tending to improve. The neurological findings are described separately. When the men were reviewed at six months there was a suggestion that some of them might have sustained long-term damage to the respiratory tract, and almost four years later 20 men had persistent respiratory symptoms. Serial measurements of ventilatory capacity revealed a marked decline in the first six months although this was not sustained.

Asthma due to non-occupational exposure to toluene (tolylene) di-isocyanate

The production of asthma by toluene di-isocyanate, aspirated into the ventilating system and emanating from the exhausts of a neighbouring factory, was established in three otherwise non-exposed clerical workers. Occupational-type exposure tests with a polyurethane varnish/toluene di-isocyanate mixture elicited vigorous and prolonged non-immediate asthmatic reactions, thus enabling identification of the otherwise, obscure etiological cause of their asthma.

Nephrology rounds, University of Iowa Hospitals: renal tubular acidosis

We have discussed two patients who had renal tubular acidosis complicated by hypokalemia. The first patient had a distal acidifying defect. Circumstantial evidence has been presented suggesting that exposure to toluene-diisocyanate or toluene-diamine played a role in the pathogenesis. The acidosis and the hypokalemia of this patient were easily corrected by the administration of small amounts of sodium bicarbonate without potassium supplementation. The second patient had an interstitial nephritis of unknown etiology and presented with moderate renal insufficiency, renal tubular acidosis, and proximal as well as distal acidifying defects. The proximal tubular dysfunction was associated with general aminoaciduria and glucosuria. This patient required large quantities of both alkali and potassium to correct the electrolyte abnormalities. The mechanisms of potassium wasting in proximal and distal renal tubular acidosis are reviewed. A classification is presented of cellular defects that may underlie the different renal acidifying defects. Attempts to distinguish between pump and permeability defects from urinary pCO2 levels must take into account the simultaneous HCO-3 concentration, since large pCO2 elevations require the presence of ample HCO-3 in the urine. Permeability defects may impair urinary acidification by either abnormal back flux of H+ out of the lumen or increased influx of HCO-3 into the lumen. In studies of acidification in vitro, amphotericin B causes increased H+ permeability and has little effect on HCO-3 permeability. Toluene-diamine causes a marked permeability defect which is reversible, but remains to be defined in terms of the ion species, HCO-3 or H+, affected. At times, hyperchloremic acidosis is caused by distal defects in net acid excretion that occur without impairment of the H+ gradient. In certain patients with hypoaldosteronism, for example, distal H+ secretion may be reduced without change in the force of the H+ pump.

Epidemiology of toluene diisocyanate (TDI)-induced respiratory disease

This paper describes our experience with the respiratory effects of TDI. Five respiratory reactions attributable to TDI are described with supporting evidence. The reactions are sensitization, irritation from overexposure, acute loss of ventilatory capacity, accelerated loss of pulmonary function and induction of a general asthmatic state. Evidence is presented that suggests a safe exposure level.