Gray area: Effects of exposure to low-level radiation

March-Novenber, 2016

When people are exposed to low-level radiation, how is their health affected? Science is currently unable to provide a clear answer to this question.

Health surveys of Fukushima children show higher incidence of thyroid cancer

Controversy over incidence of thyroid cancer

Part 1: Fukushima after five years
When people are exposed to low-level radiation, how is their health affected? Science is currently unable to provide a clear answer to this question. The fifth anniversary of the accident at the Fukushima No. 1 (Daiichi) nuclear power plant will soon arrive. My steps took me through the contaminated Fukushima landscape, where people must still contend with the threats posed by unseen radiation.

[1]Time stands still in contaminated town
[2]New distress over returning home
[3]Trying to find a compromise
[4]Turning point for voluntary evacuees
[5]Opinions are split over decontamination work
[6]Hopes and anxiety for forest industry
[7]Teaching and learning about radiation in the classroom

Part 2: Workers in Fukushima
An industrial accident claim was recognized and approved last October for a former worker at the crippled Fukushima No. 1 (Daiichi) nuclear power plant, operated by the Tokyo Electric Power Company (TEPCO). The man, 41, a resident of the city of Kitakyushu, was employed at the plant after the nuclear accident occurred and developed acute myelocytic leukemia. This is the first case in which an industrial accident claim has been approved for radiation exposure involving this nuclear accident.

[1]Radiation exposure and industrial accidents
[2]Facing risk of radiation exposure in decommissioning work
[3]Hopes and challenges for scientific clarity based on medical exam results

Part 3: Gold standard
Can low-level exposure to radiation, of 100 millisieverts or less, increase the risk of developing cancer? The answer is not clear. The lack of clarity over this question is mentioned frequently in discussions regarding exposure to low-level radiation emitted from the nuclear accident at the Fukushima No. 1 (Daiichi) nuclear power plant, operated by the Tokyo Electric Power Company (TEPCO), and is based on reports and recommendations issued by international organizations. These reports and recommendations come mainly from data and analysis compiled by the Radiation Effects Research Foundation (RERF, located in Minami Ward, Hiroshima) in its epidemiological investigation of A-bomb survivors. In this series, the Chugoku Shimbun looks at the merits, and the limitations, of these research results, known as the “gold standard” of current knowledge in this area.

[1]Data from A-bomb survivors is unmatched
[2]Research continues on relationship between low-level radiation and disease
[3]Research on differences between long-term exposure and instant exposure to radiation
[4]Call for more A-bomb research data to be released
[5]Effects of radiation are not explained only by A-bomb’s flash

Part 4: In a nuclear superpower
Seventy-one years ago, the United States opened the nuclear era by detonating atomic bombs over Hiroshima and Nagasaki, the first nuclear attacks in human history. During the Cold War, the United States and the former Soviet Union were engaged in a nuclear arms race. The harder they worked to advance their nuclear technology for both military and civilian uses, the more hibakusha (nuclear sufferers) were created. These hibakusha are different from those of Hiroshima and Nagasaki, who were exposed to a large amount of radiation instantaneously at close range. Sufferers in the United States have difficulty proving that their health has been harmed due to radiation exposure, leaving some stranded without relief measures. In this article, the Chugoku Shimbun explores the issue of low-level radiation exposure in the nuclear superpower and assesses the challenges it faces.

[1]People living in downwind area have difficulty proving damage
[2]Workers face acute anxiety in shadow of U.S. nuclear policy
[3]Research of health risks near nuclear power plants

Part 5: Search by scientists
Modern science has yet to clarify the effects of low-level radiation on the human body. This series covers the persistent efforts, and differing views, of scientists researching this “gray area.”

[Introduction] Relationship to risk of cancer
No matter how small the level of radiation is, exposure to radiation will have an adverse effect on human health in proportion to this level. Under this assumption, there is no numerical value, or threshold, below which safety can be ensured. In line with this idea, the so-called linear non-threshold (LNT) model has been adopted globally as a means of protecting the human body from exposure to radiation. Nevertheless, researchers are deeply divided over the actual effects of radiation exposure: some support the LNT model as a useful scientific assumption, while others question its validity. Does some kind of “boundary” exist where radiation exposure levels change from being safe to unsafe with regard to human health? Studies and discussions on the effects of low-level radiation are ongoing.

[1]Research on DNA repair process
[2]Why abnormalities occur in human cells
[3]Halting research on radiation hormesis
[4]New direction for risk assessment
[5]Probing the gap between reality and science

Part 6: Rethinking Fukushima
Five and a half years have passed since the accident at the Fukushima No. 1 (Daiichi) nuclear power plant, which spewed radioactive substances such as iodine and cesium over broad swaths of land and into the ocean. Health surveys carried out by the Fukushima prefectural government have found that 174 children either have or are suspected of having thyroid cancer. Studies on the natural surroundings have also been conducted. Have the effects of exposure to low-level radiation already manifested? Or will they show up in time? Scientific approaches are seeking to reveal the truth.

[1]Differing views on incidence of thyroid cancer in children
[2]Abnormal changes in plants and animals

Part 7: Path to the future
In making use of nuclear energy, human beings have opened a Pandora’s box. This series concludes with Part 7, which attempts to chart a path to the future.

[1]Sufferers of the Fukushima nuclear accident I
[2]Sufferers of the Fukushima nuclear accident II
[3]Medical exposure to radiation
[4]Future advances in radiation science

Looking back on this series