Clinical studies of workers exposed to polyvinylchloride dust

A previous study showed that exposure of workers to polyvinylchloride (PVC) dust was associated with the presence of small rounded opacities in the chest radiograph, and also with a small average reduction of the forced expiratory volume in one second (FEV1). Studies have now been carried out on selected men to determine the clinical importance of the presence of small rounded opacities and also to identify any clinical or physiological features associated with PVC dust exposure. Among 28 men with small rounded opacities, complaints of persistent bronchial mucous hypersecretion were more common (nine men) than amont 29 men of similar age, smoking habits, and dust exposures (one man, p less than 0.01), and there was a suggestion that the physical sign of late inspiratory crackles was more frequent among men with opacities (seven of 27 men) than the other men (two of 28 men, p less than 0.05). The average lung function of men with opacities was only trivially lower than that of the comparative group and the difference between the groups was not significant. In further studies 13 non-smokers with the highest PVC dust exposure and lowest FEV1 (adjusted for age, height, weight, and dust exposure) were examined. None had an observed FEV1 less than 80% of the predicted value for age and height, and these men did not differ in symptoms, signs, or lung function from non-smokers with low dust exposure and similarly low FEV1. In a similar study of 18 smokers with the highest PVC dust exposures and lowest adjusted FEV1, some men had an observed FEV1 well below 80% of predicted values for non-smokers, but with one exception no clinical or functional differences were found between then and 18 smokers with low dust exposure and similarly low FEV1. The exception was again the presence of end inspiratory crackles on auscultation, which were slightly more frequent among men with the highest dust exposures (seven men) than among those with low exposure (two men, p less than 0.06). We conclude that these findings are consistent with the suggestion that the radiographic abnormalities caused by PVC dust exposure are not associated with important functional effects or clinical illness. Further studies are desirable to examine the eventual outcome of the syndrome.     

Epidemiological study of respiratory disease in workers exposed to polyvinylchloride dust.

The respiratory health of workers exposed to polyvinylchloride (PVC) dust has been investigated in 818 men sampled from the work force of a factory manufacturing PVC. In a cross-sectional survey, the lung function and prevalences of respiratory symptoms and chest radiographic abnormalities were compared with estimates of individual PVC dust exposures based on detailed occupational histories and current measurements of respirable PVC dust. Complaints of slight exertional dyspnoea were associated with PVC dust exposure, though age and smoking effects were much stronger. The forced expired volume in one second (FEV1) and forced vital capacity (FVC) were inversely related to dust exposure after age, height, and smoking effects had been taken into account. This effect was seen principally in cigarette smokers, and there was suggestive evidence that PVC dust exposure and cigarette smoking interacted in the reduction of FEV1 and FVC. Gas transfer factor was not related to dust exposure. The chest radiographs were read according to the ILO U/C classification by three experienced readers. One reader recorded a low prevalence of small rounded opacities, and these were not related to age or dust exposure. Another reader recorded a higher prevalence of small rounded opacities category 0/1 or more, and these were related to age but not to dust exposure. The third reader recorded the highest prevalence of small rounded opacities (though none greater than category 1/1), and these were independently related both to age and to PVC dust exposure, indicating an effect of PVC dust on the appearance of the chest radiography. These appearances were so slight that only the higher sensitivity of this reader in the interpretation of profusion of small rounded opacities on the ILO U/C scale enabled detection of this effect of PVC dust. In conclusion, exposure to PVC dust is associated with some deterioration of lung function, slight abnormalities of the chest radiograph, and complaints of slight dyspnoea. The mean decline in FEV1 associated with the average dust exposure experienced in the study was small, though some of the men with higher dust exposures may have suffered clinically important loss of lung function as a result of their occupation.     

Circadian rhythms in peak expiratory flow rate in workers exposed to cotton dust.

One hundred and sixty two people working in various departments of cotton spinning and weaving mills measured and recorded their own peak expiratory flow rate (PEFR) at two hourly intervals during Monday, Wednesday, and Thursday of the same work week, from waking in the morning throughout the day until going to bed and a last time the following morning after waking. The circadian rhythm in PEFR was computed by the Halberg program. The mean amplitude of the rhythm in the group was found to be 3.3% and the acrophase fell approximately in the middle of the waking hours. Older workers and those claiming to suffer from symptoms of chronic bronchitis were found to have an amplitude significantly higher (4.1% and 3.9% respectively) than their younger or symptom free counterparts (2.6% and 2.9% respectively; p less than 0.03). The amplitude of cardroom workers (2.4%), workers with byssinosis (2.7%), and those with much exposure to airborne cotton dust (3.3%) and bacteria (2.9%) tended to be lower than that of less exposed groups such as office staff (3.9%), though the difference was significant only in the case of cardroom workers (p less than 0.04). This may be due to airborne contaminants in the working environment.     

Byssinosis: a follow-up study of workers exposed to fine grade cotton dust

A follow-up study was made in a group of cotton workers processing fine grade cotton fibres. Respiratory symptoms and ventilatory capacity were first recorded in 1962 and later in 1971. In 1962, 20 men and 23 women were examined whereas in 1971 only 15 of the men and 13 of the women were still in the mill. In 1962 no case of byssinosis was recorded. The prevalence of chronic cough and chronic bronchitis was higher among men than women. In 1971 the incidence of byssinosis was 20% in men and 23% in women and the prevalence of all other respiratory symptoms had also increased.     

Respiratory symptoms and ventilatory function changes in relation to length of exposure to cotton dust

The prevalence of byssinosis, respiratory symptoms, acute changes of ventilatory capacity over the shift, and chronic changes of ventilatory capacity were studied in two groups of non-smoking female workers exposed to practically identical concentrations of the same type of cotton dust but for very different periods of time (16 and 4 years respectively). The prevalence of non-specific respiratory symptoms increased with the duration of exposure to cotton dust only in the subjects with byssinosis. Exposure to cotton dust caused significant reductions over the shift of the mean FEV_1.0, FVC and PEF in all the groups of cotton workers examined. In byssinotics the reduction in ventilatory capacity was considerably greater in subjects with longer than in those with shorter exposure to cotton dust, while in non-byssinotics the response was approximately equal in the two groups. Inhalation of a bronchodilator at the end of the shift restored ventilatory function to its pre-shift values except in byssinotics with a longer duration of exposure to cotton dust. Chronic changes of ventilatory capacity developed only in subjects with a longer exposure to cotton dust and were common in the byssinotics.     

Pulmonary function in coal workers with Caplan's syndrome and non-rheumatoid complicated pneumosoniosis.

This retrospective study compares the pulmonary function of 24 coal workers with Caplan's syndrome with that of 36 subjects with non-rheumatoid progressive massive fibrosis (PMF). Allowing for differences in radiographical category, age, years worked underground, and smoking, obstruction to air flow as reflected in the one-second forced expiratory volume, the vital capacity, and the ratio of residual volume to total lung capacity, was significantly less in subjects with Caplan's syndrome. No significant differences in transfer factor were found. These findings may be explained by the different pathological features of the two entities. Selection bias does not appear to be responsible for the differences observed between the groups, but studies designed to eliminate this would be desirable.     

Pulmonary asbestos and dust content in East Africa.

Measurements were made of the asbestos fibre and dust content of samples from 96 surgically excised lungs; 42 necropsies on patients with lung cancer, 11 necropsies on patients with non-pulmonary malignancies, and 59 necropsies on patients without any malignant disease. The patients' ages ranged from 45 to 74 years at the time of study. None of the patients had asbestosis. The distribution of fibres and dust content of the lungs showed a log-normal distribution. There was no significant difference in fibre counts or dust content between men and women, and between lung cancer and non-cancer patients. The only group with an association with a high asbestos fibre count was four necropsy cases of pleural mesothelioma. There was no significant relationship between asbestos fibre count and dust content of the lung. The present data suggest that asbestos fibre counts below 100,000 per gram of dried lung are not related to specific asbestos disease, although in the surgical cases who were closely questioned on their residential and occupational histories most of those with fibre counts above 30,000 per gram dried lung had had occasions of definite or very likely asbestos exposure.     

Pulmonary function in acromegaly.

The lung volumes of 12 female and eight male patients with acromegaly, chosen because of the absence of associated cardiorespiratory disease, were determined physiologically and radiographically. Enlarged lung volumes were found in half the males but in none of the females, due allowance being made for the presence of a significant thoracic kyphosis. Upper airway narrowing was suggested by an increase in the expiratory-inspiratory flow rate ratio in six patients, four of whom were male, and acromegaly of the larynx was confirmed in the three subjects who consented to laryngoscopy. Upper airway obstruction is more likely to account for respiratory death in acromegaly than disordered pulmonary function in enlarged acromegalic lungs. Neither of these respiratory findings could be correlated with the fasting level of growth hormone but there was a suggestion that they were more likely to occur when the duration of the disorder was longer.     

Pulmonary infiltration after exposure to home renovation dust: histopathology and microanalysis.

A subacute self-resolving illness associated with bilateral pulmonary infiltration developed in a patient following renovation in her home. This may have been related to exposure to silicaceous plaster dust which was found in an environmental sample as well as on microanalysis of a transbronchial lung biopsy specimen and bronchoalveolar lavage fluid.     

Renal function of children exposed to cyclosporin in utero.

BACKGROUND: The use of cyclosporin (CsA) has improved graft survival in transplant (Tx) patients despite its potential nephrotoxicity. Children born to transplanted women may present with intrauterine growth retardation (IUGR). On the basis of potential reduced nephron mass both in IUGR and in newborn experimental animals exposed to CsA in utero, we investigated the renal function of children >1 year of age born to women under maintenance immunosuppression, including CsA. METHODS: Fourteen children born to 12 Tx women (nine kidney, one pancreas-kidney, one heart, one liver) were investigated using inulin clearance (C(in)), para-aminohippuric acid clearance (C(PAH)), microalbuminuria, and electrolyte reabsorption rate. RESULTS: Gestational age of the 14 infants was 34+/-3 weeks and birth weight 2018+/-620 g. During pregnancy, CsA trough blood level was 234+/-115 microg/l and plasma creatinine range was 96-136 micromol/l. Two children were excluded from the study because renal investigation led to a diagnosis of hereditary nephritis (one Alport syndrome, one familial dominant focal segmental glomerulosclerosis) that was retrospectively completed in the mother. Renal function tests were finally performed in 12 children at 2.6+/-1.8 years of age: BP 94+/-7/55+/-5 mmHg, C(in) 117+/-28 ml/min/1.73 m(2), C(PAH) 545+/-124 ml/min/1.73 m(2), filtration fraction 0.23+/-0.03, microalbuminuria 4.2+/-3.5 mg/mmol. Electrolyte tubular reabsorption rates and urine concentrating capacity were normal. CONCLUSION: These results suggest that in children born to transplanted women taking CsA, renal function develops normally despite prolonged exposure in utero.     

Self-reported low back symptoms in urban bus drivers exposed to whole-body vibration.

The prevalence of self-reported low back symptoms was investigated by a postal questionnaire in a group of 234 urban bus drivers exposed to whole-body vibration and postural stress and in a control group of 125 maintenance workers employed at the same bus municipal company. The average vertical whole-body vibration magnitude measured on the seat pan of the buses was 0.4 m/s2. After controlling for potential confounders, the prevalence odds ratios for the bus drivers compared to the controls significantly exceeded 1 for several types of low back symptoms (leg pain, acute low back pain, low back pain). The occurrence of low back symptoms increased with increasing whole-body vibration exposure expressed in terms of total (lifetime) vibration dose (years m2/s4), equivalent vibration magnitude (m/s2), and duration of exposure (years of service). The highest prevalence of disc protrusion was found among the bus drivers with more severe whole-body vibration exposure. Frequent awkward postures at work were also related to some types of low back symptoms. It is concluded that bus driving is associated with an increased risk for low back troubles. This excess risk may be due to both whole-body vibration exposure and prolonged sitting in a constrained posture. The findings of this study also indicated that among the bus drivers low back symptoms occurred at whole-body vibration exposure levels that were lower than the health-based exposure limits proposed by the International Standard ISO 2631/1.     

Hypothenar hammer syndrome in workers occupationally exposed to vibrating tools

Among 330 vibration-exposed workers, 24 cases of hypothenar hammer syndrome in 29 hands were diagnosed by arteriography. The right hand was involved in 13, the left hand in six, and both hands in five cases. The mean age was 55 years, mean duration of vibration exposure 19.4 years, and mean duration of episodic Raynaud's phenomenon 6.4 years.The vascular lesions of the ulnar arteries were classified into three major types with subtypes. Type 1: stenosis of the superficial palmar arch around the hook of the hamate. Type 2a: occlusion of the superficial palmar arch around the hook of the hamate. Type 2b: occlusion of both superficial and deep palmar arches around the hook of the hamate. Type 3a: occlusion of the ulnar artery at the proximal part of the wrist. Type 3b: occlusion of the ulnar artery near the wrist with the occlusion of the dorsal carpal branch of the ulnar artery.     

Pulmonary function in aluminium smelters.

Two studies were conducted at an aluminum smelter employing 113 male workers in the smelting process. Twenty one of the 111 men in the first study experienced chest tightness more often than once a week and had a higher prevalence of cough, dyspnoea, and nasal symptoms but not of positive skin test responses than symptomless men. Lung function in these men did not differ significantly from that in the symptomless men at the beginning of the working week and only marginal deterioration occurred over the week. In the second study serial spirometric measurements were obtained over several shifts in a subset of 31 men from the first study. Impairment of ventilatory function on exposure to smelting fumes was demonstrated in 18 men. Analysis of all data from the 31 subjects revealed that ventilatory function varied significantly in association with heavy exposure to potfumes and a history of recurrent chest tightness. The findings of these two studies indicate that aluminum smelting fumes can cause bronchoconstriction in susceptible individuals. The reaction is dose dependent and is more severe in those with a history of recurrent chest tightness.     

Screening and surveillance for occupational cholangiocarcinoma in workers exposed to organic solvents

Purpose

This study aimed to establish an efficient strategy for screening and surveillance for occupational cholangiocarcinoma.

Methods

We evaluated the consecutive changes in laboratory findings during regular health examinations and in abdominal ultrasonography findings before the diagnosis of occupational cholangiocarcinoma in nine patients. The results of laboratory tests and abdominal ultrasonography at the time of diagnosis were also examined.

Results

In all patients, the serum γ-glutamyl transpeptidase (γ-GTP) activity increased several years before the diagnosis of cholangiocarcinoma. The serum alanine aminotransferase (ALT) activity also increased several years before the diagnosis, following an increase in the serum aspartate aminotransferase (AST) activity in most patients. Abdominal ultrasonography before the diagnosis revealed regional dilatation of the bile ducts, which continued to enlarge. At the time of diagnosis, the γ-GTP, AST, and ALT activities were increased in nine, seven, and seven patients, respectively. The regional dilatation of bile ducts without tumor-induced stenosis, dilated bile ducts due to tumor-induced stenosis, space-occupying lesions, and/or lymph node swelling were observed. The serum concentrations of carbohydrate antigen 19-9 (CA 19-9) and/or carcinoembryonic antigen (CEA) were increased in all patients.

Conclusions

Regular health examinations with a combination of ultrasonography and laboratory tests including the γ-GTP, AST, ALT, CA 19-9, and CEA levels are useful for screening and surveillance for occupational cholangiocarcinoma.

     

Regional lung function in asbestos workers.

Regional lung function was measured using radioactive xenon-133 in a group of normal subjects and in two groups of asbestos workers. When compared with the normal group, patients with pulmonary asbestosis showed impaired ventilation of the lower zones. Subjects with calcified pleural plaques without radiological evidence of lung parenchymal fibrosis did not show this abnormality.