title: The bystander effect in experimental systems and compatibility with radon-induced lung cancer in humans.
abstract: Bystander effects following exposure to alpha-particles have been observed in C3H 10T1/2 cells and in other experimental systems, and imply that linearly extrapolating low-dose risks from high-dose data might materially underestimate risk. The ratio of lung cancer risk among persons exposed to low and high doses of radon daughters is 2.4-4.0, with an upper 95% confidence limit (CL) of about 14. Assuming that the bystander effect observed in the C3H 10T 1/2 data applies to human lung cells in vivo, the epidemiological data imply that the number of neighbouring cells that can contribute to the bystander effect is between 0 and 1, with an upper 95% CL of about 7. As a consequence, the bystander effect observed in the C3H 10T1/2 system probably does not play a large part in the process of radon-induced lung carcinogenesis in humans. Other experimental data relating to the bystander effect after alpha-particle exposure are surveyed; some of these data are more compatible with the epidemiological data.
authors.affiliation: Department of Epidemiology and Public Health, Imperial College of Science, Technology and Medicine, London, UK. mark.little@ic.ac.uk
authors.forename: M P
authors.initials: MP
authors.lastname: Little
authors.forename: R
authors.initials: R
authors.lastname: Wakeford
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects; D000395:Air Pollutants, Occupational / Q000009:adverse effects; D000396:Air Pollutants, Radioactive / Q000009:adverse effects*; D000818:Animals; D024201:Bystander Effect; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic / Q000528:radiation effects; D006801:Humans; D008175:Lung Neoplasms / Q000209:etiology* / Q000503:physiopathology*; D051379:Mice; D009381:Neoplasms, Radiation-Induced / Q000209:etiology / Q000503:physiopathology; D011829:Radiation Dosage; D011886:Radon / Q000009:adverse effects*; D012306:Risk
chemical_list: D000393:Air Pollutants; D000395:Air Pollutants, Occupational; D000396:Air Pollutants, Radioactive; D011886:Radon