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J W Skidmore

Publications and source records attributed to J W Skidmore.

At least 19 recordsLinked to original sources
PubMed1993

A study of Spanish sepiolite workers.

BACKGROUND: Sepiolite is an absorbent clay that is used as pet litter. It forms thin crystals, which are a transition between chain and layered silicates. Inhalation studies in animals have shown no evidence of pulmonary damage. This paper reports a cross sectional study of the total work force of the largest sepiolite production plant in the world. METHODS: Two hundred and eighteen workers (210 men and eight women) were studied. Height, age, and smoking history were recorded. Chest radiographs were read according to the International Labour Office (ILO) classification by two readers. Readings were used to construct a numerical score, which was then used in statistical analyses. Forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were divided by the square of the height. Casella size selective personal samplers were used in randomly selected operatives to collect dust eight years before the rest of the study was carried out. These samples were evaluated gravimetrically. Total dust samples were examined by optical and electron microscopes. Results were analysed by bivariate linear regression, chi 2 tests, and analysis of variance. RESULTS: When allowance was made for smoking habit workers exposed to dry dust showed a significantly greater decline in FEV1 with age than workers with little exposure to dry dust. A similar pattern applied to FVC. Radiographic score showed deterioration with age but no clear differences from other variables. High concentrations of dust were found in the bagging department and also in the classifier shed. CONCLUSIONS: The major finding was that lung function deteriorated more rapidly in those who had had more exposure to dust, but there was no evidence of any accompanying radiographic change.

Adult↗
PubMed1985

Erionite exposure and mesotheliomas in rats.

Epidemiological and environmental surveys in the Cappadocian region of Turkey have linked the high incidence of pleural and peritoneal mesothelioma in the occupants of some villages with the zeolite fibres released from the locally occurring volcanic tuff. In view of the low ambient fibre concentrations and the extraordinary incidence of mesothelioma a study to test the hypothesis of high biological activity for the zeolite fibres was required. Experimental studies using both intrapleural inoculation and inhalation techniques have been undertaken with the erionite from this region and from Oregon in the United States. Additionally a non-fibrous zeolite from Japan and a synthetic non-fibrous zeolite of similar chemical composition to erionite have been included in the experiments. In these studies the samples from Oregon and Turkey produced a very high incidence of tumours. All the rats inoculated intrapleurally with Oregon erionite and almost all those inoculated with the Turkish fibre died with a mesothelioma. Inhalation of the Oregon erionite induced a similar effect. No other dusts we have investigated have produced this high incidence of tumours particularly following inhalation. These studies demonstrate that we now have a valuable new fibre for experimental study and a possible hazard to man in regions other then Turkey.

Aluminum Silicates↗
PubMed1983

Cytotoxicity of talc for macrophages in vitro.

The cytotoxicity of seven specimens of respirable talc dust for mouse peritoneal macrophages in vitro was studied. All talcs showed modest but consistent macrophage cytotoxicity and would be expected to be fibrogenic in vivo. Available data suggest that under certain circumstances respirable talc can cause lung fibrosis in animal inhalation studies. As most of the talc specimens under investigation were of high purity it seemed unlikely that the cytotoxicity was due to the presence of small quantities of contaminating minerals.

Animals↗
PubMed1983

In vitro genotoxic activities of fibrous erionite.

A high incidence of mesothelioma has been reported from some villages in Cappadocia, Turkey. This type of cancer is usually associated with the inhalation of asbestos, but on the basis of the most prevalent fibre in the dust from these villages, the Turkish outbreak has been attributed to the inhalation of zeolite fibres. A counter hypothesis, based on the detection of very small quantities of chrysotile and tremolite in strata samples and human lung tissue, postulates a significant role of these minerals as one of several factors contributing to pleural disease. A respirable fraction of erionite, (from Oregon, USA, but with similar characteristics to the fibres found in Turkey), has some in vitro genotoxic properties associated with many conventional carcinogens. In this study these fibres caused an increase in morphological transformation and unscheduled DNA repair synthesis (UDS) in C3H10T1/2 cells and UDS in the human lung cell line--A549. It is therefore suggested that exposure to fibrous erionite alone may be sufficient to cause the high incidence of pleural tumours observed in Turkey.

Aluminum Silicates↗
PubMed1983

Environmental history of a factory producing friction material.

The fibre concentrations generated during the production of friction materials, incorporating asbestos, over the past 60 years have been studied to provide cumulative dust exposure data for a mortality study of the work-force. Chrysotile has been used almost exclusively during this period. The measurements made routinely by the factory staff provided information from 1950 onwards; concentrations for earlier years were derived from simulation studies using original materials, machines, and methods. These have shown that while high concentrations prevailed in the earliest years dust suppression measures initiated in 1931, and other factors, reduced the time-weighted average concentrations to moderate levels. There were two four-year periods when the production of brake blocks incorporating crocidolite occupied a well-defined area of the factory. The simulation of this production was not permissible, but the employees concerned could be identified.

Air Pollutants↗
PubMed1981

Malignant mesothelioma and radiological chest abnormalities in two villages in Central Turkey. An epidemiological and environmental investigation.

A comparative epidemiological and environmental study in two neighbouring villages, Karain and Karlin, in Central Turkey showed an excess adult mortality, shortening of life expectancy, and an excess of pleural radiological abnormalities in Karain. This supports an earlier report of an endemic of pleural mesothelioma in the village. Concentrations of airborne respirable fibres were uniformly very low in Karlik and higher in some of the air samples from Karain, the fibres being similar in composition to those of erionite-a mineral of the zeolite family and the major contributor to the Karain clouds. This is compatible with the hypothesis of a causal association between endemic mesothelioma and inhalation of erionite fibres, but the fibre concentrations in all samples are so low as to leave in question the aetiological role of erionite. In addition to their local importance these results may have relevance for the wider scientific and public-health issue of long-term inhalation of mineral fibres at low concentrations.

Adolescent↗
PubMed1980

The comparative effects of three chrysotiles by injection and inhalation in rats.

Three samples of chrysotile, UICC Canadian chrysotile, a grade 7 Canadian chrysotile and a super fine sample (SFA) also from a Canadian mine, were compared in animal experiments using rats of the Wistar strain. All the materials contained impurities. The average length and diameter of the fibres contained in the UICC chrysotile cloud were less than for the other two chrysotiles, but the higher fibre count meant that the UICC cloud contained more fibres of all lengths. In the first experiment, groups of 48 rats were injected intrapleurally with 20 mg of respirable dust. Mesotheliomas occurred with all samples; 18 with SFA, 13 with grade 7, and five with UICC chrysotile. In the second experiment, rats were exposed to a respirable cloud of about 1 mg/m3 for 35 hours a week. Groups of 48 rats were exposed for three months, 24 for six months and 24 for 12 months. Malignant lung tumours occurred with all the dusts; 10 with UICC chrysotile, 4 with SFA, and 1 with grade 7. However, only one of these tumours, obtained with SFA, was a mesothelioma.

Animals↗
PubMed1975

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.

Air Pollutants↗
PubMed1975

Animal experiments with talc.

Italian talc has been tested on rats using three routes, intra-pleural inoculation, inhalation and ingestion. Groups exposed to superfine chrysotile asbestos and untreated controls were included for comparison. In all the experiments animals were allowed to live out their lives. The intra-pleural inoculation of talc produced no mesotheliomas in contrast to eighteen produced by the chrysotile asbestos. After ingestion, one leiomyosarcoma occurred with Italian talc and one with chrysotile asbestos. Whether these tumours are a consequence of the feeding is uncertain. The inhalation studies demonstrated that with equal dosage, talc can produce a similar amount of fibrosis as asbestos. However, the chrysotile exposed rats developed lung adenomas, adenomatosis and an adenocarcinoma, whereas the only lung tumour seen in animals exposed to talc was a small adenoma, which may have been an incidental finding.

Animals↗
PubMed1974

The effects of the inhalation of asbestos in rats.

Two experiments in which SPF Wistar rats were exposed by inhalation to dust clouds of the UICC standard reference samples for periods of between one day and 2 years are described. All the samples of asbestos produced asbestosis which continued to progress after removal from exposure but only a little fibrosis was observed in control rats. Lung tumours, ranging in severity from adenomata to squamous carcinomata, were produced by all samples but in the controls there were only a few adenomata and none of the more serious tumours. Of the 20 tumours which metastasized, 16 occurred after exposure to one or other of the 2 chrysotile samples. In addition, a total of 11 mesotheliomata occurred, 4 of which were with crocidolite and 4 with Canadian chrysotile. Two of the mesotheliomata occurred with only one day's exposure to asbestos. There was a positive association between asbestosis and lung tumours.

Adenocarcinoma↗