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4.  Biological monitoring of workers exposed to 4,4'-methylenebis (2-chloroaniline) (MBOCA). 
A biological monitoring programme has been developed for assessing occupational exposure to 4,4'-methylenebis (2-chloroaniline) (MBOCA) in a factory which manufactures polyurethane elastomers. In a systematic programme of biological monitoring over a five year period urinary MBOCA concentrations have been used to provide evidence of absorption of MBOCA. Improvements in the handling and use of MBOCA have coincided with a steady reduction in the urinary MBOCA concentrations.
PMCID: PMC1009383  PMID: 6498117
5.  Uptake, distribution, metabolism, and elimination of styrene in man. A comparison between single exposure and co-exposure with acetone. 
Six male subjects were exposed for two hours during light physical exercise to 2.81 mmol/m3 (293 mg/m3) of styrene on one occasion and to a mixture of 2.89 mmol/m3 (301 mg/m3) of styrene and 21.3 mmol/m3 (1240 mg/m3) of acetone on another (combination study). About 68% of the dose (somewhat more than 4 mmol) of styrene was taken up. The arterial blood concentration of styrene reached a relatively stable level after about 75 minutes of exposure of about 18 and 20 mumol/l after the single and combined exposure, respectively. Calculated values of mean blood clearance were 1.9 l/min in the styrene study and 1.6 l/min in the combination study; the half life of styrene in blood was about 40 minutes in both studies. The concentration of non-conjugated styrene glycol increased linearly during exposure and reached about 3 mumol/l at the end of exposure and was eliminated with a half life of about 70 minutes. Styrene-7,8-oxide was detected and quantified in the blood in a complementary study. The half lives for the excretion of mandelic and phenylglyoxylic acid in the urine were about four and nine hours, respectively, in both studies.
PMCID: PMC1009382  PMID: 6498116
6.  n-Hexane metabolism in occupationally exposed workers. 
Lung uptake and excretion of n-hexane were studied in ten workers in a shoe factory. Simultaneous samples of inhaled and alveolar air were collected with the aid of a Rhan-Otis valve, personal samplers, and charcoal tubes. Alveolar excretion was monitored during a six hour postexposure period. Uptake was calculated from lung ventilation, the retention coefficient, and environmental concentrations. The amount of exhaled n-hexane was calculated from the decay curve. According to the experimental data, alveolar retention was about 25% of the inhaled n-hexane, corresponding to a lung uptake of about 17%. The postexposure alveolar excretion was about 10% of the total uptake. The main metabolites of n-hexane were identified and measured by capillary GC/MS in spot urine samples collected before, at the end, and 15 hours after the same working shift. Urinary concentrations were low, though related to n-hexane in the air. 2,5-Hexanedione in the end of shift samples gave the best estimate of overall exposure. About 3 mg/g creatinine of 2,5-hexanedione would correspond to about 50 ppm of n-hexane in the air (mean daily exposure).
PMCID: PMC1009381  PMID: 6498115
7.  Neurophysiological studies on the relation between the structural properties and neurotoxicity of aliphatic hydrocarbon compounds in rats. 
In order to determine the specific structural properties responsible for neurotoxic activity, the comparative neurotoxicity of n-hexane, methyl n-butyl ketone, 2,5-hexanedione, and their relatives was investigated in the peripheral nerves of rats. The maximum conduction velocity of motor and sensory fibres and the motor distal latency of the tail nerves of rats were periodically examined in animals receiving repeated subcutaneous injections of 11 aliphatic monoketone or diketone compounds and their relatives for prolonged periods. A study of the comparative neurotoxicity of n-hexane, methyl n-butyl ketone, and their metabolites showed that 2,5-hexanedione was the most actively neurotoxic. Furthermore, a study of other symmetrical diketones with different carbon numbers showed that 2,4-pentanedione, which is structurally similar to 2,5-hexanedione, possessed a different type of neurotoxic activity than 2,5-hexanedione. Regarding aliphatic monoketone compounds, acetone, 2-pentanone, 2-heptanone, and 2-octanone were confirmed non-neurotoxic for the peripheral nervous system. Evidence from some previous reports, however, suggested that 3-heptanone, 4-octanone, and 5-nonanone might produce neuropathies by being converted to 2,5-diketones under specific conditions.
PMCID: PMC1009380  PMID: 6093852
8.  A further experimental study of the antisilicotic effect of glutamate. 
Two groups of rats were exposed to quartz dust for six months and in addition one group was given drinking water containing 1.5% sodium glutamate while the second received only water. In the rats receiving glutamate we observed (a) evidence for a considerably reduced cytotoxic effect of the quartz on cells obtained by bronchopulmonary lavage, (b) a reduction in dust retention in the lungs, especially in the tracheobronchial lymph nodes, (c) a considerable reduction in the weight gain in the lungs and in their hydroxyproline and lipid contents, and (d) the inhibition of the formation of silicotic nodules. Polarographic studies of the oxygen consumption of peritoneal macrophages from rats receiving glutamate showed that glutamate prevents the adverse effects of quartz on mitochondrial oxidative processes.
PMCID: PMC1009379  PMID: 6093851
9.  Cell population and histochemistry of asbestos related lesions of rat pleural cavity after injection of various inorganic dusts. 
Rats injected intrapleurally with either crocidolite or chrysotile asbestos or silica or saline, were killed at intervals up to 2 years of age. The pleural cavities were washed out immediately after death and the washing used for enumerating cells. In addition tissue from granulomas and mesotheliomas was sectioned and stained for lysosomal enzymes. The total cellular response to silica found in the washout showed a pronounced increase when compared with either asbestos dust or controls; crocidolite gave a decreased response in an early group of the individual cells studied. The most important finding was a decrease in the number of mast cells found to be associated with the injection of both types of fibres. Crocidolite induced granulomas showed the presence of lysosomal enzymes and non-specific esterase in mononuclear cells and giant cells, even two years after injection. With chrysotile, giant cells were only present up to three to four months, and few positively staining cells were noted after 18 months. While the response of cells in the pleural cavity does not differ greatly between the two types of fibres, that in the granulomas highlights the longer lasting action of crocidolite.
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PMCID: PMC1009377  PMID: 6093850
10.  Acute exposure of symptomatic steelworkers to sulphur dioxide and carbon dust: effects on mucociliary transport, pulmonary function, and bronchial reactivity. 
Nine steel workers participated in controlled exposures to sulphur dioxide alone and sulphur dioxide plus carbon dust (5 ppm and 10 mg/m3, respectively). All were experiencing work related respiratory difficulties. Bronchial clearance was measured using radioaerosol inhalations and external detection. Results were variable and no statistically significant changes were observed. One asthmatic showed a complete cessation of clearance during exposure to sulphur dioxide and carbon dust. Bronchial reactivity was found to be significantly raised after exposure to sulphur dioxide but equivocal results were found after exposure to sulphur dioxide and carbon dust. Pronounced changes in pulmonary function were seen only in the two asthmatic subjects. They could not tolerate the levels, indicating that these threshold limit values are too high, at least for these individuals who showed much greater sensitivity to the pollutants than the others.
PMCID: PMC1009376  PMID: 6498113
11.  A cross sectional study of employees with potential occupational exposure to ethylene oxide. 
A cross sectional study was conducted on 84 employees potentially exposed to ethylene oxide (EO) to determine whether they had a higher prevalence of abnormalities of the haematopoietic, hepatic, or renal systems than a control group individually matched on age, hire date, race, smoking habits, alcohol history, and date of examination. Potential exposures were estimated to be generally below the current threshold limit value of 10 ppm, with most below 1 ppm. Results of the haematological and biochemical studies were similar in the two groups. A statistically significant (p = 0.035) increase in the prevalence of proteinuria was noted among the EO group which warrants further investigation.
PMCID: PMC1009375  PMID: 6333892
12.  Acute lung function response to cotton dust in atopic and non-atopic individuals. 
Acute spirometric responses to inhaled cotton dust were examined in a population of 226 healthy, non-asthmatic adults whose atopic status had been evaluated by skin prick tests to 10 common environmental allergens. Exposure to cotton dust occurred in model cardrooms where elutriated dust levels were carefully controlled (1.02 mg/m3). Atopy, defined as positive prick tests to at least two allergens, was observed in 26% of subjects. Significant forced expiratory volume in one second (FEV1) decrements occurred after exposure to cotton dust independent of atopic status (p less than 0.001). The mean FEV1 decline in atopic subjects, however, was significantly greater than in non-atopic subjects (p less than 0.05). Degree of atopy, as measured by number of positive skin tests, also exhibited a significant association with cotton induced decrements in FEV1 (p less than 0.05). These data suggest that atopy may be an important determinant of the magnitude of the acute pulmonary response to cotton dust. This may reflect the non-specific airways hyperresponsiveness that has been described in non-asthmatic, atopic individuals.
PMCID: PMC1009374  PMID: 6498112
13.  Cotton induced bronchoconstriction detected by a forced random noise oscillator. 
Lung function responses to inhaled cotton dust were evaluated in a group of 58 healthy subjects by spirometry (MEFV curves) and forced random noise impedance parameters. Twenty-one of these subjects were also examined by body plethysmography to assess changes in airway resistance (Raw). For the study group as a whole, alterations in lung mechanical function after exposure to cotton dust were detected by maximal expiratory volumes and flows (p less than 0.001) and impedance parameters (p less than 0.01) but not by Raw. Subjects showing responses in MEFV curves also showed increases in Thevenin or effective resistance at low frequencies (R1, R5-9, R5-9/R20-24), suggesting that the limitation of flow occurred predominantly in the peripheral airways. By contrast, non-responders on MEFV measurements were found to have significant increases in effective resistance both at low and at high frequencies (R1, R5-9, R20-24), suggesting a central airways effect. MEFV curve non-responders also exhibited a significantly lower baseline effective resistance profile than MEFV curve responders. The data indicate that under the conditions of the experiment measures of the Thevenin resistance (real part of impedence) by the forced random noise method are reliable indicators of cotton induced bronchoconstriction. Measurement variability, however, suggests that, at present, these are more appropriate for group studies and should remain adjuncts to standard tests of lung function such as spirometry.
PMCID: PMC1009373  PMID: 6498111
14.  Respiratory morbidity in wollastonite workers. 
Medical and environmental surveys were conducted at a wollastonite mine and mill in 1976 and in 1982. Health testing included chest radiography, spirometry, and a questionnaire. Workers at a nearby electronics plant were also examined in 1982 for a comparison of lung function and respiratory symptoms. Both wollastonite and control workers showed significant smoking effects for chronic respiratory symptoms, but differences between the groups were not detected. Pneumoconiosis was found in 3% (3/108) of the wollastonite workers in 1982, but none showed a significant progression from their 1976 radiographs. The lung function tests of the 108 wollastonite workers examined in 1982 showed dust related changes in FEV1, FEV1/FVC ratio, and peak flow rate which were independent of age, height, and smoking habit (p less than 0.01). For non-smokers alone, only the FEV1/FVC ratio declined significantly with dust-years of exposure (p less than 0.01). The comparison of lung function in 1982 between a high dust exposed subgroup of wollastonite workers and the control population showed a significantly lower FEV1/FVC ratio and peak flow rate in the study group (p less than 0.05). Analysis of 1976-82 changes in pulmonary function showed that wollastonite workers with higher dust exposure had a significantly greater decline in peak flow over the period than workers with lower exposures (p less than 0.01). These data suggest that long term cumulative exposure to wollastonite may impair ventilatory capacity as reflected by changes in the FEV1/FVC ratio and peak flow rate.
PMCID: PMC1009372  PMID: 6093849
15.  Quantitative x ray microanalysis of pulmonary mineral particles in a patient with pneumoconiosis and two primary lung tumours. 
The right upper lung lobe of a 74 year old man was resected for a central tumour. Two primary cancers were found; a central small cell carcinoma and a peripheral squamous cell carcinoma. In addition, the peripheral lung tissue showed generalised peribronchiolar fibrosis extending from the non-respiratory bronchioles to the level of the alveolar ducts. Abundant asbestos bodies and large amounts of black dust were seen around the bronchioles. Pulmonary mineral particles were studied by quantitative energy dispersive x ray microanalysis (EDS) using scanning transmission electron microscopy (STEM). The x ray spectra for mineral particles were measured in thin sections, and the characteristic peak intensities of the elements were converted to weight fractions (in oxides). The results enabled the minerals present to be identified and their presence confirmed by calculating the mineral formula. These originated from nine natural minerals, anthophyllite and chrysotile asbestos, talc, and quartz, feldspars, and muscovite, which are components of sand, and also from two artificial mullites used in fire clay. The exposure history of the patient explained the most likely origins of the minerals detected. The patient had been a mason for 23 years, repairing and demolishing stoves and fireplaces and using asbestos for insulation work.
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PMCID: PMC1009371  PMID: 6093848
16.  Comparison of radiographic appearances with associated pathology and lung dust content in a group of coalworkers. 
The pathology and dust content of lungs from 261 coalminers in relation to the appearances of their chest radiographs taken within four years of death were examined. Radiological opacities of coalworkers' pneumoconiosis were more profuse the more dust was retained in lungs. Among the men who had mined low rank coal--that is, with a relatively high proportion of ash--the increase in profusion was most closely related to the ash component of the dust, whereas in men who had mined high rank coal both coal and ash increased in the lungs in relation to radiological profusion. The fine p type of opacity was found to be associated with more dust and a higher proportion of coal and less ash than the nodular r opacity, and was also more likely to be associated with emphysema. The pathological basis of the different types of opacity found on the radiographs of coalminers related to the number, size, and nodularity of the dust lesions. Larger fibrotic lesions were likely to appear as r opacities, whereas fine reticular dust deposition was most likely to present as p opacities, q opacities showing a mixture of appearances. The study has shown that the composition of dust retained in the lung, as well as its amount, makes an important contribution to the radiographic appearances of pneumoconiosis. In particular, the r type of lesion on the radiograph of a low rank coalminer indicates the possibility of a silicotic like lesion.
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PMCID: PMC1009370  PMID: 6498110
17.  Alpha 1 antitrypsin and lung function in British coalminers. 
Alpha 1 antitrypsin (alpha 1 AT) serum concentration was determined for a group of coalminers with particularly low levels of lung function, not thought to be explicable in terms of age and dust exposure, and compared with two other groups of coalminers who had average or above average lung function. There was no evidence for an alpha 1 AT deficiency in coalminers with poor lung function. On the contrary, a reactionary increase was evident, even in non-smokers, which may have resulted from the high frequency of chest disease in these men. Within the non-smoking group men with poor lung function had been exposed to higher mean levels of dust, and a greater proportion had early signs of bronchitis. There was no indication that the presence or degree of pneumoconiosis was affecting the results.
PMCID: PMC1009369  PMID: 6333891
18.  Wheat flour sensitisation and airways disease in urban bakers. 
A total of 176 bakers and 24 subjects employed as bread slicers and wrappers were studied to examine the effect of occupational category on respiratory symptoms, ventilatory capacity, non-specific bronchial reactivity, and prick skin test responses to wheat and common allergens. Bakers had a greater prevalence of attacks of wheeze and dyspnoea and more frequently considered that work affected their chests than did slicers and wrappers. Bakers with a history of asthma with onset since starting work in a bakery had a greater prevalence of chronic cough and sputum, increased bronchial reactivity, and positive prick skin test responses to wheat and common allergens than other bakers. There was a significant association between the frequency of positive prick skin tests to wheat and common allergens, suggesting that prior atopy facilitates sensitisation to cereal antigens. The frequency of positive prick skin responses to common allergens, however, declined with increasing baking duration whereas the frequency of positive skin responses to wheat increased with increasing baking duration, suggesting that subjects who were sensitised to common allergens were leaving the industry whereas subjects who stayed in the industry increased their risk of developing sensitisation to wheat. Oven handlers had a greater prevalence of attacks of wheeze and dyspnoea and more frequently considered that work affected their chests than either dough makers or general bakers. They also had a greater prevalence of positive prick skin test responses to wheat than dough makers or general bakers. Oven handlers also had a lower mean standardised casual FEV1 than either general bakers or dough makers. Thus oven handlers appear to have a greater risk of developing respiratory allergy and airflow obstruction than bakers in other occupational categories.
PMCID: PMC1009368  PMID: 6498109
19.  Rice millers' syndrome: a preliminary report. 
A study was carried out to determine the health effects of rice husk dust in Malaysian rice millers. The study population consisted of 122 male Malay workers from three rice mills, with 42 controls of similar age, sex, ethnic group, and agricultural work background. Interviews using standardised questionnaires, physical examination, total and differential white cell counts, chest radiographs, and lung function tests were performed on each of the millers and the controls. Environmental dust monitoring was also carried out in the three rice mills. Clinical, haematological, and radiological findings suggest that a distinct clinical syndrome seems to be associated with exposure to rice husk dust. The manifestations of this "rice millers' syndrome" include acute and chronic irritant effects affecting the eyes, skin, and upper respiratory tract; allergic responses such as nasal catarrh, tightness of chest, asthma, and eosinophilia; and radiological opacities in the chest, probably representing early silicosis or extrinsic allergic alveolitis.
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PMCID: PMC1009367  PMID: 6498108
20.  Scrotal cancer in the West Midlands 1936-76. 
Between 1936 and 1976, 344 cases of scrotal cancer were registered in the West Midlands Region. There was a considerable increase in the number of registrations after 1955, the figures remaining high until the 1970s since when they appear to be falling towards the low level seen in the early years of registration. By the end of December 1981 250 deaths had occurred. The cause of death was known in 226 cases and of these, 97 (42.9%) were attributed to cancer of the scrotum, 40 (17.7%) to other malignancies, and 89 (39.4%) to other causes, scrotal cancer not being mentioned on the death certificate. The mean age at registration was 59.3 years and at death 66 years. Mean survival was 6.6 years with a five year survival rate of 51%. Survival was shorter in men who presented with palpable lymph nodes and greater in those treated with surgery alone. Occupations were known for all but 28 of the cases and of these, 61.9% had been exposed to mineral oil and a further 7.8% to pitch and tar. Among the occupations with exposure to mineral oil, tool setters and tool fitters accounted for the greatest proportion, 89 men having followed those trades. In 74 cases second primary tumours were registered after the scrotal primary, mostly in the skin and bronchus. There was no relation between the development of second primary tumours and exposure to mineral oil or to pitch and tar.
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PMCID: PMC1009366  PMID: 6498107
21.  Mortality and incidence of cancer of workers in the man made vitreous fibres producing industry: an international investigation at 13 European plants. 
A total of 25 146 workers at 13 plants producing man made mineral fibres (MMMF) in seven European countries (Denmark, Finland, Federal Republic of Germany, Italy, Norway, Sweden, and United Kingdom) were studied in a historical cohort investigation. At 12 of the 13 plants an environmental survey was carried out to determine present day concentrations of airborne man made mineral fibres that showed levels of respirable fibres usually below 1 f/ml and most commonly in the range 0.01 to 0.1 f/ml. Workers were entered into the cohort at the moment of their first employment at one of the 13 factories (which started to operate between 1900 and 1955), and were followed up to at least 31 December 1977. Three per cent of the workers were lost to follow up. National death rates and national cancer incidence rates, where applicable, were used for each of the seven countries for comparison with the workers' cohort. A single death from mesothelioma was reported out of a total of 309 353 person-years of observation. No consistent differences (within and between plants) were noted between observed and expected numbers concerning individual causes of death or individual cancer sites, apart from lung cancer. For this cause a tendency was observed for the standardised mortality ratio (SMR) to increase with time from first employment. When the data from all the plants were pooled a statistically significant raised SMR of 192 (17 observed, 8.9 expected; 95% confidence interval 117-307) appeared in the group with 30 years or more since first employment. The relevance of this finding, to which different factors including uncontrolled confounders such as smoking habits may have contributed, cannot be established at present. The result is suggestive, however, of an increased risk associated with the man made mineral fibres working environment of 30 or more years ago.
PMCID: PMC1009365  PMID: 6498106
22.  Histological types of malignant mesothelioma and asbestos exposure. 
The Los Angeles County Cancer Surveillance Program abstracts hospital pathology records on almost all cases of cancer occurring in the county. Those cases of pleural and peritoneal mesothelioma that occurred between 1972 and 1978 were identified. Occupational histories were obtained from interviews, and the histopathology of the tumours was reviewed by a member of a mesothelioma reference panel who was unaware of the exposure histories. The relation of asbestos exposure to the three histological types of mesothelioma (epithelial, mesenchymal, and mixed) was studied among the 29 cases for whom occupational histories were available and who were also considered to have histopathology consistent with mesothelioma. The proportion of cases exposed to asbestos was high for both the epithelial (11/17, 65%) and mixed histological types (6/11, 55%). The single case of mesothelioma classified as a mesenchymal type was also exposed to asbestos. Cases who had worked in shipyards were represented in each of the three groups. In cases who had worked in asbestos production and manufacture an exclusively epithelial type of tumour was observed. In cases who had worked as insulators or in heating trades the histological type was predominantly (3/4) mixed. These data do not support the hypothesis that any specific histological type of mesothelioma is especially related to asbestos exposure.
PMCID: PMC1009378  PMID: 6498114
23.  Telangiectasia in aluminium workers: a follow up. 
A five step investigation was carried out to gain a better understanding of the morbidity that accompanied the development of telangiectasia on aluminium workers and to find its cause. Fifty workers with multiple telangiectasia when matched with normal controls showed the same amount of illness except that evidence of ischaemia on the ECG was found in nine cases and one control. The cases did not show an excess of abnormal biochemical tests. The basic histopathological lesion affected the surrounding tissue rather than the vessels themselves. Working in the current environment and wearing masks seems to protect young workers from developing the lesions. The Soderberg and not the prebake process was associated with the lesions; the causative agent is probably a gas that contains both hydrocarbons and fluoride components emitted from the electrolytic reactors.
PMCID: PMC1069359  PMID: 6743585
24.  Ethylene thiourea: thyroid function in two groups of exposed workers. 
Ethylene thiourea is manufactured at one factory in the United Kingdom and is mixed into masterbatch rubber at another. Clinical examinations and thyroid function tests were carried out over a period of three years on eight process workers and five mixers and on matched controls. The results show that the exposed mixers, but not exposed process workers, have significantly lower levels of total thyroxine (T4) than the controls. One mixer had an appreciably raised level of thyroid stimulation hormone (TSH).
PMCID: PMC1069358  PMID: 6743584
25.  Respiratory symptoms and lung function in a group of solderers. 
A total of 1611 women working in a large electronics company were interviewed using a modified version of the Medical Research Council's questionnaire on respiratory symptoms, and their lung function was tested using a Vitalograph dry wedge spirometer. When the prevalence of symptoms was compared using the chi 2 test among four occupational groups--namely, solderers, ex-solderers, non-solderers, and office workers--few significant differences were found. The group of ex-solderers tended to have a greater prevalence of symptoms than the other three groups. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were measured, and when these were compared for smokers, the office workers were found to have a greater mean age adjusted FVC and FEV1 than the three other groups. The pattern was less distinct for non-smokers. When duration of exposure to solder fumes was allowed for, differences in lung function were more suggestive of being related to smoking habit than occupational exposure to solder fumes.
PMCID: PMC1069356  PMID: 6743582

Results 1-25 (96)