There are so many contradictory research papers published on health effects of radiation especially low dose radiation. Some are arguing for LNT model, others are for Threshold or Hormesis model. Can anyone provide the latest status with explanation?
There is no definitive answer.
http://www.nature.com/news/researchers-pin-down-risks-of-low-dose-radiation-1.17876
www.avensonline.org/wp-content/uploads/JES-2471-4879-02-0005.pdf
Thank you very much Mr. Florian Glodeanu. I think more extensive research is needed.
The LNT is a model for regulatory purposes. The assumption of linearity was based on genetic effects. The LNT was adopted in the 1950s before low dose effects were available. The data at that time was for doses >4Gy. Today, ICRP accepts that low-dose genetic effects are minimal to non-existent. The basis for protection from ionizing radiation is cancer induction. The conclusion from ICRP is the cancer data is not inconsistent with the LNT so the LNT is conservatively protective at low doses. Low doses are doses less than doses that cause deterministic effects. The cancer risk is considered stochastic.
The cancer stochastic risk is based on the Japanese Atomic Bomb Survivors. A linear model is fit to calculated excess cancers for an irregular dose intervals. No excess cancers are observed above the detection limit for any dose interval.
Information on hormesis is found at
http://radiationeffects.org
The latest status is that the LNT model for stochastic effects (cancer and heritable effects) and the threhold model for tissue reactions (deterministic/nonstochatic effects). Hormesis model is not used for the radiation protection purpose, and this is also the case for non-targeted effects. You may be interested in my paper that summarized changes in the classification of radiatino effects for radiatin protection purposes.
Article Classification of radiation effects for dose limitation purp...
The latest report on the solid cancer incidence data in atomic bomb survivors has been published. https://www.ncbi.nlm.nih.gov/pubmed/28319463
The sex averaged dose response now exhibits an significant upward curvature (p = 0.03) in a linear quadratic model assuming the common curvature for males and females that was estimated to be 0.22 per Gy [95% confidence intervals (CIs): 0.01 to 0.60]. For this, the shape of the dose response was significantly different between sexes, such that the dose response was linear for females, but exhibited an significant upward curvature for males.
A threshold was not significant. For females, the estimated threshold of 0.08 Gy was not different from 0, and the upper bound of the 95% CI was 0.2 Gy. For males, the best estimate of 0.75 Gy was not different from 0, and the upper bound of the 95% CI was 0.8 Gy.
To address whether recent epidemiological studies support the linear non-threshold model for use in radiation protection, the US National Council on Radiation Protection and Measurements (NCRP) established the Scientific Committee 1-25 (SC 1-25) "Recent Epidemiologic Studies and Implications for the Linear-Nonthreshold Model" in late 2015 under Program Area Committee 1 (PAC1).
http://ncrponline.org/program-areas/sc-1-25-recent-epidemiologic-studies-and-implications-for-the-linear-nonthreshold-model/
SC 1-25 is working on the draft of a commentary, of which final form to be published late this year as NCRP Commentary. Will keep you updated.
As aforementioned, the NCRP SC 1-25 "Recent Epidemiologic Studies and Implications for the Linear-Nonthreshold Model" is reviewing recent epidemiological studies focusing on dose-response models, including threshold, and the relevance to radiation protection, and working on the draft of a commentary.
The final form will be published as the NCRP Commentary later this year, but the outline of the SC 1-25 draft has just been published online. https://www.ncbi.nlm.nih.gov/pubmed/28532210
Will keep you updated.
The US National Council on Radiation Protection and Measurements (NCRP) has just started public consultation for the draft Commentary “Implications of Recent Epidemiologic Studies for the Linear-Nonthreshold Model and Radiation Protection” prepared by Scientific Committee 1-25 (SC 1-25) under Program Area Committee 1 (PAC 1). Please see “Documents in Review” at http://ncrponline.org/ to download the draft and post comments (due 16 October 2017). The information on SC 1-25 “Recent Epidemiologic Studies and Implications for the Linear-Nonthreshold Model” is available at http://ncrponline.org/program-areas/sc-1-25-recent-epidemiologic-studies-and-implications-for-the-linear-nonthreshold-model/ . The information on PAC 1 “Basic Criteria, Epidemiology, Radiobiology, and Risk” is available at http://ncrponline.org/program-areas/pac-1-basic-criteria-epidemiology-radiobiology-and-risk/ .
The NCRP report recommended by Hamada,
“Implications of Recent Epidemiologic Studies for the Linear-Nonthreshold Model and Radiation Protection”,
is an insipid repetition of previous NCRP documents. It recommends that nothing be done to the regulator stance on the LNT. It does nothing for answering the question posed.
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