Lung Tumours in Rats After Inhalation of Radon and Co-carcinogenic Factors

Purpose: To determine the risks of lung tumors after inhalation of radon together with co-carcinogens

Status: 1976 - 1982, data in ERAD except for groups indicated in red

Treatment: Inhalation of radon (0.1-0.3 μm AMAD 6.2% unattached), injection of different co-carcinogenic factors. Controls injected at different ages (+ d from an age of 2.5 months). For further details see individual experiments below.

Dosimetry: Activity inhaled (dose from daughter products deposited 2-3 mGy/WLM)

Endpoints: Life-span study (spontaneous death) with macroscopic/microscopic pathology unless otherwise stated below

Animal: Male Sprague-Dawley SPF rats of different ages as indicated below; controls see 02.01

Results: Beta-naphtoflavone (BNF) is a specific promoter of epidermoid lung cancer; therefore, the study of the influence of BNF on radon initiation or promotion of lung cancer seemed of particular interest for the understanding of the carcinogenic action of radon. If radon was given prior to BNF, lung cancer developed after 3 months; radon thus behaved as an initiator with BNF promoting the appearance of cancer. Different application forms, intramuscular or intraperitoneal injection, gave similar results. An intra-tracheal application of BNF resulted in 9 lung cancers in 10 rats, all of which were adenocarcinomas whereas BNF-induced carcinomas are usually of the epidermoid type. Further studies were carried out varying concentrations of radon and/or BNF.