An international team of experts in the study of cancer risks associated with low-dose ionizing radiation published the monograph, “Epidemiological studies of low-dose ionizing radiation and cancer: Summary bias assessment and meta-analysis,” in the Journal of the National Cancer Institute on July 13, 2020. It is well established that ionizing radiation causes cancer through direct DNA damage. The general public are exposed to low doses of ionizing radiation from medical exposures like computed tomography (CT) scans, naturally occurring radiation (emitted from bedrock with the earth’s crust and cosmic rays emitted by the sun), and occupational exposures to medical, aircrew and nuclear workers. A key question for low-dose exposures is how much of the damage can be repaired and whether other mechanisms, including inflammation, also play a role. This critical question has been long debated for radiation protection standards. After combing data from 26 epidemiological studies the authors found clear evidence of excess cancer risk from low dose ionizing radiation: 17 of 22 studies showed risk for solid cancers and 17 of 20 studies showed risk for leukemia. The summary risk estimates were statistically significant and the magnitude of risk (per unit dose) was consistent with studies of populations exposed to higher doses.
DCEG 13th July 2020 read more »
Kunihiko Iida wants the world to know that the atomic bombs the United States dropped on Hiroshima and Nagasaki 75 years ago next month are still claiming lives and causing suffering. Iida was 3 years old in August 1945. His father had died in battle; he was living with his mother and her parents in a house 900 meters from Hiroshima’s hypocenter, the spot right beneath the detonation. The blast crumpled the house. The family fled the city, but Iida’s mother and older sister soon died from their injuries, a fact the little boy didn’t grasp. “Until I entered elementary school, I thought they were living and that we would meet someday,” he says. His injuries left him bedridden for years, and he has suffered debilitating illnesses ever since. Childhood anemia caused him to collapse at school. He’s had ulcers and asthma, underwent two surgeries to remove brain tumors, and now has thyroid growths. “There has never been a break in these illnesses,” he says. The survivors’ ranks are now rapidly thinning. About 70% of the original 120,000 participants enrolled in RERF’s Life Span Study (LSS) have died; most of those remaining are in their 80s and 90s. “We have an ethical obligation” to follow the cohort through the last surviving member, Niwa says—but at the same time, “We have to expand our mission.” RERF researchers believe they can continue to gather epidemiological findings from existing life and health histories of the LSS participants, but they are also starting entirely new studies, for example of the molecular mechanisms by which radiation exposure leads to cancer. And biological samples from 30,000 study participants collected over 7 decades await genomic analysis. One unanswered question is whether an individual’s exposure to radiation can genetically damage their offspring. “No one can say that there is no effect on the second generation,” says Katsuhiro Hirano, a Hiroshima area schoolteacher whose mother was irradiated; he now heads an association of second-generation bomb survivors that is pushing for greater recognition of their health concerns. So far, there’s no evidence that radiation damage can be passed down, but Hirano says survivors’ worries resonate among others exposed to radiation, including victims of nuclear accidents, power plant workers, and uranium miners. “This campaign is not just about ourselves,” he says. “We want to work with radiation victims the world over.”
Science Mag 23rd July 2020 read more »