PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-25 (73)
 

Clipboard (0)
None
Journals
Year of Publication
1.  Erratum 
PMCID: PMC1008090
7.  Tetramethyl lead absorption: a report of human exposure to a high level of tetramethyl lead. 
Accidental human exposure to a high level of tetramethyl lead is described. Tetramethyl lead is blended with petrol as an antiknock agent, and it has similar physical properties to tetraethyl lead. The patient had high levels of lead in urine, averaging 4-75 mumol (983 mug) daily for the first four days after exposure and he continued to have raised levels of urinary lead for six months. He had no symptoms or physical signs of lead poisoning and comparisons are made between this case and previously reported cases of poisoning by tetraethyl lead. In the cases of tetraethyl lead poisoning all the patients had symptoms, some severe, yet in no instance did the urinary lead levels approach those described in this patient. The effects of chelation therapy with calcium disodium versenate are discussed and the results are similar to those found in tetraethyl lead poisoning. Blood lead levels of up to 3-91 mumol/l (81 mug/100 g) occurred but these levels were not raised commensurate with the urinary lead output. The levels of deltaaminolaevulinic acid (ALA) in the urine were not significantly raised and this report shows that the urinary lead levels give a better guide to the degree of absorption of tetramethyl lead compared with the blood lead or urinary ALA levels. The report illustrates that tetramethyl lead is less toxic to man than tetraethyl lead.
PMCID: PMC1008084  PMID: 811247
8.  Kinetic studies on sex difference in susceptibility to chronic benzene intoxication--with special reference to body fat content. 
The sex difference in the susceptibility to haematopoietic disorders induced by benzene was studied kinetically with a special reference to its relation with the body fat content. In rats of both sexes with a large body fat content, benzene was eliminated more slowly and remained in the body for a longer time than in rats with a small body fat content. In accord with this finding, the decrease in white blood cell numbers during a chronic benzene exposure was observed only in the groups of rats which had a large volume of fat tissue. In an experimental human exposure, the elimination of benzene was slower in the females than in the males. The kinetic study revealed that the slower elimination in the females is due primarily to the bulky distribution of body fat tissue in that sex. From these results obtained from the experimental exposure of men and rats to benzene, it was concluded that the human female, with her massive body fat tissue, shows an inherent disposition to be susceptible to a chemical such as benzene which has a high affinity with fat tissue.
PMCID: PMC1008083  PMID: 1103957
9.  Effect of hydrofluoric acid on glucose metabolism of the mouse studied by whole-body autoradiography. 
Distribution of radioactive carbon from [U-14C]glucose in the mouse poisoned by hydrofluoric acid has been studied by whole-body autoradiography. Under normal conditions, the highest autoradiographic density was found in the Harder's gland, palatine gland, sublingual gland, large intestinal mucosa, and many regions of the central nervous system 30 minutes after intraperitoneal injection of [U-14C]glucose. On the other hand, after hydrofluoric acid poisoning, it was found that (1) the radioactivity of brain was unchanged throughout all the poisoning; (2) the liver, renal cortex, lung, and blood showed an increase in radioactivity at 180 minutes of poisoning; (3) the abdominal cavity showed a tendency to residual radioactivity with the poisoning; (4) by contrast, Harder's gland, the palatine gland, sublingual gland, and large intestinal mucosa showed a decrease in radioactivity at 180 minutes of poisoning.
Images
PMCID: PMC1008082  PMID: 1201258
10.  Behaviour of rats exposed to trichloroethylene vapour. 
Rats were exposed to trichloroethylene (TCE) vapour for about five five-day weeks at concentrations from 100 to 1 000 ppm, and at 100 ppm for 12 1/2 weeks. The social behaviour of paired male rats was observed periodically in the home cage for five minutes after they had been exposed to TCE. The principal finding was a consistent reduction of up to 24% in the total acitivity. A single day's exposure to TCE was sufficient at the highest concentration. At 100 ppm, a similar decline in activity was significant after 1 1/2 weeks' exposure in one experiment and 8 1/2 weeks' in another. The decline in activity was fairly uniform and not usually because of specific reductions in particular kinds of behaviour. However, exploration of the cage and submission to, or escape from, the other rat were sometimes specifically reduced. In an 'exploration-thirst' test, rats were deprived of water overnight and placed on two or three occasions in a previously unfamiliar cage. Rats exposed to 100, 200, or 1 000 ppm TCE found water and began drinking sooner than their controls without altering the rate of movement about the cage. These results suggest lowered performance in a familiar situation where rats are usually very active and some loss of inhibitory control in an unfamiliar one. At the present threshold limit value, repeated exposure to TCE eventually had effects similar to those of one day's exposure to a higher concentration, but only after a widely variable delay.
PMCID: PMC1008081  PMID: 1238103
11.  Occupational asthma after inhalation of dust of the proteolytic enzyme, papain. 
Papain is a proteolytic enzyme widely used by biochemists. In experiments on animals papain has been shown to cause emphysema either when they inhaled a single small dose or after intratracheal inhalation. Four food technologists were occupationally exposed to heavy concentrations of papain dust in air. Subjects 1 and 2 developed an immediate acute asthmatic reaction, and symptoms of obstructive airways disease persisted for some months while each remained in the same working area, presumably exposed to small gradually diminishing amounts of residual papain dust. Tests of respiratory function were carried out on all four subjects 1 1/2 years later and showed in subjects 1 and 3 minimal abnormality of bronchial reactivity and of ventilation distribution. Review of the literature reveals only two reports of asthma resulting from papain inhalation, although its antigenic and skin sensitizing qualities have been known and described for many years. It seems remarkable that a substance such as papain, shown to be a potent cause of lung damage in experimental animals, should have produced so little evidence of abnormality in our subjects after considerable exposure. Follow-up ventilatory function tests may cast further light on this but we postulate that the asthmatic response may be biologically protective and those lacking this reaction could later develop emphysema as a long-term outcome.
PMCID: PMC1008080  PMID: 1201257
12.  Epidemiological investigation of the role of family susceptibility and occupational and family histories in the development of byssinosis among workers exposed to flax dust. 
Epidemiological investigation of 475 workers exposed to dust in flax processing has shown that family susceptibility has a decisive role in the development of byssinosis in those workers. Workers whose fathers had occupational history of exposure to flax dust were more resistant to the development of the disease than those whose fathers had no such history. Such tolerance was much higher in workers whose fathers were byssinotic than those with byssinosis-free fathers. Further hereditary and immunological investigations are, however, needed.
PMCID: PMC1008079  PMID: 1201256
13.  Comparative study of the smooth muscle contractor activity of airborne dusts and of dustiness in cotton, flax, and jute mills. 
A bioassay technique using isolated guinea-pig ileum was employed to compare the smooth muscle contractor activity of various dusts from mills in which the prevalence of byssinosis was known. The activity of dust from a mill spinning a coarse grade of cotton was several times greater than that in dust from a mill processing a fine grade of cotton. There was a similar order in the difference of the prevalence of byssinosis in these mills. However, the activities of fine cotton, flax, and jute dusts were very similar to each other, in spite of marked differences in the prevalence of byssinosis in these mills. For cotton dust, smooth muscle contractor activity was associated with all particle sizes, although the lowest level of activity was found in the largest sized fraction (less than 2 mm). Activity in the cotton dust extracts was not correlated with nitrogen, carbohydrate, or potassium content. However, about one-fifth of the activity of a cotton dust extract was associated with an insoluble particulate fraction. The possible chemical nature of the water-soluble contractor agent is discussed. It is concluded that, until the role of this agent in the pathogenesis of byssinosis has been established, the bioassay technique cannot be employed as a means of assessing the byssinogenic potential of cotton dust.
PMCID: PMC1008078  PMID: 1201255
14.  Lung function in textile workers. 
Acute changes in ventilatory function during a workshift with exposure to hemp, flax, and cotton dust were measured on Mondays in a group of 61 textile workers, all working on carding machines. In addition, single-breath diffusing capacity (DLCOSB) was measured before dust exposure on Monday in 30 of the 61 workers. Large acute reductions during dust exposure were recorded in maximum expiratory flow rate at 50% VC (MEF50%), ranging from 38 to 22%. Acute reductions of FEV1-0 were considerably smaller, ranging from 17 to 9%. There was a statistically significant increase in residual volume (RV) with very small and insignificant changes in total lung capacity (TLC). Although preshift FEV1-0 and FVC were decreased, DLCOSB was within normal limits. Plethysmographic measurements in six healthy volunteers exposed to hemp-dust extract confirmed the results obtained in textile workers, that is, that TLC does not change significantly during dust-induced airway constriction and that maximum expiratory flow rate at 50% VC (MEF50%) is a more sensitive test than FEV1-0 in detecting acute ventilatory changes caused by the dust extract.
PMCID: PMC1008077  PMID: 1103956
15.  Classification of radiological appearance and the derivation of a numerical score. 
Approaches to the use of the International Labour Office U/C Classification of radiological appearances are considered in the context of multiple readers recording different degrees of abnormality. The Panel on Survey Radiology has been set up to provide a basis for standardization. An example of how the panel may be used in this role is given. The approach will depend on the standards maintained by the panel and on a greater understanding of the appearances associated with differing exposures.
PMCID: PMC1008076  PMID: 1201254
16.  Reading chest radiographs for pneumoconiosis by computer. 
Computer programs for measuring simple pneumoconiosis in radiographs are described and assessed. The 36 films studied had been read by 11 skilled human observers and a 'radiological score' of pneumoconiotic severity was therefore available for each film. The computer assigns to each square grid of side 3-6 mm a measure which reflects the unevenness of the density distribution in that grid. The 'computed score' is defined as the mean diversity over all relevant grids in both lung fields. On the set of 36 films the correlation between radiological score and computed score was 0-88. By contrast, the correlation between the score assigned by a single observer and the average of the scores assigned by the other 10 was in the range 0-95 to 0-98. The program can use the computed score to classify a film into one of the four major International Labour Office (ILO) U/C categories, the success rate of this process being 80% compared with those quoted by other workers in the range 45%-65%. If the films used in this study be typical, then the program described may form the basis of an automatic method for measuring pneumoconiosis in epidemiological work.
Images
PMCID: PMC1008075  PMID: 1103955
23.  Percivall Pott and cancer scroti. 
Images
PMCID: PMC1008067  PMID: 1098690
24.  An evaluation of effect of airborne dust from a cotton mill on the guinea-pig ileum with reference to byssinosis. 
The effect of airborne dust on the guinea-pig ileum was studied. Tyrode extracts of airborne dust collected freshly in the cardroom of a cotton mill, and extracts of air pollutant samples drawn on the roof of the mill and of the local town hall were all found to induce the guinea-pig ileum to contract when applied in a tissue-bath. However, the force of contraction with air pollutants was rather greater than that with the cardroom dust. Considering the variables involved, the ileum response to the cardroom dust may have been due to ordinary air pollutants which constitute a significant part of the dust. It is concluded that this pharmacological phenomenon is probably not relevant in the context of byssinosis.
Images
PMCID: PMC1008066  PMID: 1156573
25.  Pilot study of closing volume in byssinosis. 
A study of the relative sensitivities of forced expiratory volume in one second (FEV1), maximal mid-expiratory flow (MMF), and closing volume (CV) in the detection of subjects with byssinosis was carried out in a North Carolina cotton mill. Altogether 35 workers participated in the study. Of these, nine showed a decline in FEV1 of 10% or more during the first work shift that followed the weekend break. Twelve subjects showed a decrease in MMF of 15% or more. In contrast only six workers exhibited a 10% increase in closing capacity, while ten showed a 10% increase in CV. Recent evidence of the magnitude of variability in closing volume manoeuvres suggests that our chosen level of change was too low, A 40% change in CV would have identified only five subjects. CV is a more complex manoeuvre for the subject being tested and for the technician to perform, is more time consuming, and is subject to greater variation. To have any advantage over spirometry, CV would have to be appreciably more sensitive. Our study suggests that it is not. However, the MMF may prove to be more sensitive than the FEV1 in the detection of byssinosis.
PMCID: PMC1008065  PMID: 1156572

Results 1-25 (73)