Radiation hormesis: historical perspective and implications for low-dose cancer risk assessment.
نویسنده
چکیده
Current guidelines for limiting exposure of humans to ionizing radiation are based on the linear-no-threshold (LNT) hypothesis for radiation carcinogenesis under which cancer risk increases linearly as the radiation dose increases. With the LNT model even a very small dose could cause cancer and the model is used in establishing guidelines for limiting radiation exposure of humans. A slope change at low doses and dose rates is implemented using an empirical dose and dose rate effectiveness factor (DDREF). This imposes usually unacknowledged nonlinearity but not a threshold in the dose-response curve for cancer induction. In contrast, with the hormetic model, low doses of radiation reduce the cancer incidence while it is elevated after high doses. Based on a review of epidemiological and other data for exposure to low radiation doses and dose rates, it was found that the LNT model fails badly. Cancer risk after ordinarily encountered radiation exposure (medical X-rays, natural background radiation, etc.) is much lower than projections based on the LNT model and is often less than the risk for spontaneous cancer (a hormetic response). Understanding the mechanistic basis for hormetic responses will provide new insights about both risks and benefits from low-dose radiation exposure.
منابع مشابه
Hormesis: implications for cancer risk assessment.
Current guidelines for cancer risk assessment emphasize a toxicant's "mode of action", rather than its empirically derived dose-response relationship, for determining whether linear low-dose extrapolation is appropriate. Thus, for reasons of policy, demonstration of hormesis is generally insufficient to justify a non-linear approach, although it may provide important insights into the actions o...
متن کاملHormesis: Principles and Applications for Pharmacology and Toxicology
The present assessment places hormetic dose responses within an historical context, documenting its origin, rejection by the biomedical community during the early decades of the 20 due to its close association with homeopathy and its revitalization during the later decades of the past century as the biomedical and toxicological communities became very interested in low dose effects of drugs and...
متن کاملPerspective on the use of LNT for radiation protection and risk assessment by the U.S. Environmental Protection Agency.
The U.S. Environmental Protection Agency (EPA) bases its risk assessments, regulatory limits, and nonregulatory guidelines for population exposures to low level ionizing radiation on the linear no-threshold (LNT) hypothesis, which assumes that the risk of cancer due to a low dose exposure is proportional to dose, with no threshold. The use of LNT for radiation protection purposes has been repea...
متن کاملIt's time for a new low-dose-radiation risk assessment paradigm--one that acknowledges hormesis.
The current system of radiation protection for humans is based on the linear-no-threshold (LNT) risk-assessment paradigm. Perceived harm to irradiated nuclear workers and the public is mainly reflected through calculated hypothetical increased cancers. The LNT-based system of protection employs easy-to-implement measures of radiation exposure. Such measures include the equivalent dose (a biolog...
متن کاملRadiation hormesis and adoptive response induced by low doses of limiting radiation
Ionizing radiation has long been known to produce detrimental biological effects. Although these harmful effects are the results of high doses of exposure, some other maladies such as mutation and cancer seems to be induced at low doses of exposure. In recent decades, however, some pioneer scientists have indicated that ionizing radiation like many other essential agents has toxic effects ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Dose-response : a publication of International Hormesis Society
دوره 8 2 شماره
صفحات -
تاریخ انتشار 2010