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J C Heath

Publications and source records attributed to J C Heath.

13 recordsLinked to original sources
PubMed1988

Apparent synergy between chrysotile asbestos and N-nitrosoheptamethyleneimine in the induction of pulmonary tumours in rats.

Environmental carcinogenesis in man is widely accepted to be a multifactorial process, and in the causation of lung cancers it is suspected that low levels of systemic carcinogens may act synergistically with inhaled particulates so that some exposed individuals are at increased risk. In the present study the carcinogenic effects of low levels of industrially/environmentally significant particulate materials (chrysotile asbestos and metallic cadmium) and a putative systemic carcinogen, N-nitrosoheptamethyleneimine (NHMI), were investigated in the laboratory rat, using this as a model of potential human exposure. The overall lung tumour incidence rate in the groups of animals receiving chrysotile and NHMI together (8/50) or chrysotile, cadmium and NHMI together (6/44) was substantially higher than in the groups receiving chrysotile alone (1/86) or chrysotile and cadmium (1/94) or NHMI alone (2/48). The results demonstrated apparent synergy between chrysotile and NHMI in the induction of lung tumours. Incidence of pulmonary hyperplastic lesions paralleled the trend in tumour incidence. Cadmium had little or no influence on the incidence of either lung tumours or hyperplastic lesions. This study helps to evaluate further the role of asbestos in the causation of lung cancer. It is suggested that people who are or have been exposed to chrysotile asbestos may show a significantly elevated risk of lung cancer if concomitantly or subsequently exposed to tumour initiating agents.

Animals↗
PubMed1986

Apparent synergy in lung carcinogenesis: interactions between N-nitrosoheptamethyleneimine, particulate cadmium and crocidolite asbestos fibres in rats.

Environmental carcinogenesis in man is widely accepted to be a multifactorial process, and in the causation of lung cancers it is suspected that low levels of systemic carcinogens may act synergistically with inhaled particulates so that some exposed individuals are at increased risk. In the present study the carcinogenic effects of low levels of industrially and environmentally significant particulate materials (crocidolite asbestos and metallic cadmium) and a putative systemic carcinogen, N-nitrosoheptamethyleneimine (NHMI), were investigated in the laboratory rat, using this as a model of potential human exposure. The overall lung tumour incidence rate in the group of animals receiving crocidolite, cadmium and NHMI (14/45) was significantly higher than in the groups of animals receiving either crocidolite and cadmium together (2/51) or crocidolite and NHMI together (7/42). The results demonstrated an apparent synergy between cadmium and NHMI in the presence of crocidolite in the causation of lung cancer in rats, a finding which was confirmed statistically. This study helps to further evaluate and define the roles of asbestos and particulate cadmium in the causation of lung cancer. It is suggested that people who are exposed through occupation and/or environment to cadmium and asbestos and to low levels of systemic carcinogens may show a significantly elevated risk of lung cancer.

Animals↗
PubMed1986

Asbestos bodies in rat lung following intratracheal instillation of chrysotile.

Asbestos bodies in rat lung have rarely been reported, and just one previous record of their formation from chrysotile fibres in the rat is known. This paper illustrates the production of numerous true asbestos bodies in the lungs of Lister hooded rats after a single small intratracheal dose of lightly milled chrysotile. The demonstration of these bodies is particularly useful because uncoated chrysotile fibres in lung tissue cannot normally be visualized by light microscopy; the detection of asbestos bodies, and therefore of asbestos fibres, provides a means of directly relating asbestos exposure to observed tissue lesions. The asbestos bodies detected in the present study were nearly always associated with small pulmonary fibrotic lesions. The bodies ranged in length from 5 to 80 micron and were up to 5 micron in diameter. Small spheres, rods and bodies the shape of a comma were common; larger beaded structures were somewhat rarer. The bodies were visible in tissue sections stained routinely with modified Azan stain and with haematoxylin and eosin, but their detection and localization was enhanced by the use of Perls' Prussian blue stain in association with a pale eosin counterstain.

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