Occupational Cancer. Modifying Factors in Experimental Lung Cancer.
NIOSH 1980 Jun:23-26
Environmental factors leading to lung cancer, individual variability in susceptibility and experimental models of human respiratory cancer, were discussed. In one study, benzo(a)pyrene (50328) (BP) adsorbed onto ferric-oxide (1309371) dust (FeO-BP), or ground together with the dust, was intratracheally instilled into Syrian- golden-hamsters. A single injection had a toxic effect on tracheobronchial epithelium. Continuing injections caused a large area to become squamous metaplastic with keratinization at its surface. For the most part these lesions were reversible. Additional injections resulted in damage of respiratory epithelium with toxic changes in nuclei. Basal cell hyperplasia and focal areas seemed to grow extensively. Finally, underlying soft tissue became suffused with malignant cells. Injection of BP that was ground with dust particles showed an increased risk of tumor induction as opposed to administration of the BP/dust physical mixture. Carbon particles mixed with BP potentiated the carcinogenic effect more than iron dust. Hamsters anesthetized with sodium-barbital (57443) or ether (60297) had a higher incidence of tumors than methoxyflurane (76380) anesthetized animals; the response was dose and time dependent. Small doses of FeO-BP elicited a very low cancer incidence, however, when this treatment was followed by injection of diethylnitrosamine (55185) (DEN) malignant tumors occurred earlier and in larger numbers; DEN alone was not malignant. When FeO-BP administration was followed with methylnitrosourea (684935), tumor incidence was much greater than with the two carcinogens acting individually. Employment of FeO-BP and polonium- 210 (13981527) had a simple additive effect. Modification of the cellular immune system, treatment with antioxidants and vitamin-A (68268) reduced tumor incidence. The greater incidence of tumors in hamsters treated with anesthetics was concluded to be related to reduced clearance rates of carcinogens from the lungs. The author concluded that in carcinogenesis three elements could be identified: exposure, susceptibility, and modulation. Interactions varied according to specific agents, sequence, and timing of additions.
NIOSH-Contract; Contract-210-79-0009; Pulmonary-cancer; Lung-irritants; Carcinogenesis; Occupational-exposure; Occupational-respiratory-disease; Laboratory-animals; In-vivo-studies; Medical-research; Synergism;
50-32-8; 1309-37-1; 57-44-3; 60-29-7; 76-38-0; 55-18-5; 684-93-5; 13981-52-7; 68-26-8;
Mixed Exposures; Work Environment and Workforce;
Occupational Safety and Health Symposia 1979, NIOSH, U.S. Department of Health and Human Services, Cincinnati, Ohio, DHHS (NIOSH) Publication No. 80-139