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Radiation | Nuclear Radiation | Ionizing Radiation | Health Effects.

from World Nuclear Association – Updated January 2015

Low-level radiation effects”

A lot of research has been undertaken on the effects of low-level radiation. The findings have failed to support the so-called linear no-threshold (LNT) hypothesis. This theory assumes that the demonstrated relationships between radiation dose and adverse effects at high levels of exposure also applies to low levels and provides the (deliberately conservative) basis of occupational health and other radiation protection standards.”

Increasing evidence suggests that there may be a threshold between 100 and 700 mSv below which no harmful effects of radiation occur. However, this is not yet accepted by national or international radiation protection bodies as sufficiently well-proven to be taken into official standards. However, at low levels of exposure, the body’s natural mechanisms do repair radiation and other damage to cells soon after it occurs, and some adaptive response is stimulated which protects cells and tissues, as with exposure to other external agents at low levels. The ICRP recommends that the LNT model should be assumed for the purpose of optimising radiation protection practices, but that it should not be used for estimating the health effects of exposures to small radiation doses received by large numbers of people over long periods of time.”

In addition, there is evidence of beneficial effect from low-level radiation (up to about 10 mSv/yr). This ‘radiation hormesis’ may be due to an adaptive response by the body’s cells, the same as that with other toxins at low doses. In the case of carcinogens such as ionizing radiation, the beneficial effect is seen both in lower incidence of cancer and in resistance to the effects of higher doses. This potential hormetic effect is most clearly evident in the data (see Appendix) for over 50,000 survivors of the Hiroshima bomb 1.5 to 3 km from the hypocenter, with dose range 1 to 100 mSv, compared with a large control group.”


A Sane and Sober Look at the USS Reagan Radiation Contamination Incident.

by Brian Hanley, February 6, 2014, International Policy Digest (.org)

“The proposition that the USS Reagan crew were contaminated with significant doses of radiation is not credible. Suggestions that the US Navy is somehow hiding something because the ship was not brought back to a US port are equally so. The idea that the crew of the ship are suffering radiation related injury or cancer caused by Fukushima fallout is fantasy. It is just not possible based on what science knows.”

Indoor Radon Levels and Lung Cancer Incidence on Guam.


Radon (Rn) is a naturally occurring, radioactive gas that impacts air quality world-wide. It is a known carcinogen and considered by the United States Environmental Protection Agency (U.S. EPA) to be the second leading cause of lung cancer after tobacco smoking. Of several known isotopes of radon, 222Rn is the most stable with a half-life of approximately four days. This particular isotope is associated with the uranium (238U) decay series and accounts for most public ionizing radiation exposures. Most global indoor 222Rn emanates from granitic bedrocks located underneath buildings. While such rocks are absent on Guam, the karst limestone formations that overlay the island’s basement volcanics (basalt) are of biogenic origin and are believed to be a significant source of radon. In a recent multi-year survey conducted on Guam by the local EPA, indoor 222Rn levels exceeded the U.S. EPA air quality standard of 4 pCi/L in ~40% of all buildings tested. Concentrations were log-normally distributed and exceeded 300 pCi/L in two instances. Weighted average indoor 222Rn levels were generally much higher in villages from the northern half of the island where limestone coverage predominates. The relationship between 222Rn and lung cancer incidence on Guam was examined in the study reported here. The results were strongly suggestive of a hormetic effect existing between the two variables. Possible confounding effects attributable to smoking and ethnicity were examined and found to be insignificant. In fact, ethnic groups predominantly confined to the northern half of the island (i.e., Filipinos and all other Asians as a collective group) showed considerably lower cancer incidence and mortality rates than the indigenous Chamorro people who are well represented island-wide. The findings of the study lend further weight to numerous other reports that suggest low-level exposures to 222Rn have a beneficial health effect. They also support a growing critique of the rationale behind the U.S. EPA adopted linear-no-threshold toxicological model, which assumes that any dose of radiation is harmful, no matter how small. Finally, they also imply that the current U.S. EPA action level of 4 pCi/L for indoor radon is overly conservative and needlessly prompting homeowners to install radon mitigation systems into buildings that really don’t need them.


  • radon;
  • radon progeny;
  • lung cancer;
  • confounding effects;
  • hormesis;
  • Risk assessment