Domestic radon risks may be dominated by bystander effects--but the risks are unlikely to be greater than we thought.
نویسندگان
چکیده
Radon risks derive from exposure of bronchio-epithelial cells to alpha particles. Alpha-particle exposure can result in bystander effects when irradiated cells emit signals resulting in damage to nearby unirradiated bystander cells. Bystander effects can cause downwardly-curving dose-response relations and inverse dose-rate effects. We have extended a quantitative mechanistic model of bystander effects to include protracted exposure, with inverse dose-rate effects attributed to replenishment, during exposure, of a subpopulation of cells which are hypersensitive to bystander signals. In this approach, bystander effects and the inverse dose-rate effect are manifestations of the same basic phenomenon. The model was fitted to dose- and dose-rate dependent radon-exposed miner data; the results suggest that one directly-hit target cell can send bystander signals to about 50 neighboring cells and that, in the case of domestic radon exposures, the risk could be dominated by bystander effects. The analysis concludes that a naive linear extrapolation of radon miner data to low doses, without accounting for dose rate/bystander effects, would result in an underestimation of domestic radon risks by about a factor of approximately 4. However, recent domestic radon risk estimates (BEIR VI) have already applied a phenomenological correction factor of approximately 4 for inverse dose-rate effects, and have thus already implicitly taken into account corrections which we here suggest are due to bystander effects. Thus current domestic radon risk estimates are unlikely to be underestimates as a result of bystander effects.
منابع مشابه
Do low dose-rate bystander eVects in uence domestic radon risks?
exposure (NCRP 1987) . For a variety of reasons, Purpose : Radon risks derive from exposure of bronchio-epithelial however, direct epidemiological assessment of the cells to high-linear energy transfer (LET) a-particles. a-particle risks from domestic radon exposure is diYcult, exposure can result in bystander eVects, where irradiated cells resulting in risk estimates with wide con dence inter...
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ورودعنوان ژورنال:
- Health physics
دوره 85 1 شماره
صفحات -
تاریخ انتشار 2003