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May 4, 2021 · Two studies led by NCI researchers examined the genetic changes in people exposed to radiation from the Chernobyl accident and their children. The studies found no evidence of transgenerational mutations, but detected more DNA damage in thyroid cancers.
- International research teams explore genetic effects of Chernobyl ...
In two landmark studies, researchers have used cutting-edge...
- Strong effects of ionizing radiation from Chernobyl on mutation rates
In this paper we use a meta-analysis to examine the...
- International research teams explore genetic effects of Chernobyl ...
Jul 18, 2019 · Scientists collect information about the animals by sampling radioactive dung and soil and watching animals using camera traps. The Chernobyl exclusion zone is a mostly-off-limits area covering over 1,600 square miles around the accident. The exclusion zone is a sort of radioactive wildlife refuge.
- Anne Marie Helmenstine, Ph.D.
Apr 22, 2021 · Researchers used DNA sequencing to investigate the potential health effects of radiation exposure from the 1986 accident at the Chernobyl nuclear power plant. They found no evidence of genetic changes being passed from parent to child, but documented the genetic changes in thyroid cancers caused by radiation.
- Overview
- No excess mutations in the next generation
- Detailed portrait of thyroid cancer
- Studies of the Chernobyl survivors must continue
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The largest and most advanced study of its kind not only updates past results, it also provides new details on how fallout from the disaster caused certain cancers.
On the morning of April 26, 1986, a reactor in a nuclear power plant in what’s now northern Ukraine exploded and burned—triggering what would become history’s deadliest nuclear accident. The hellish fire belched out immense clouds of radioactive fallout that entered people’s lungs, settled on homes, fields, and livestock pastures, and infiltrated their supplies. Milk, salami, and eggs had become, in the words of one nuclear engineer, “a radioactive byproduct.”
In the years since, researchers have monitored the health of populations that lived through the Chernobyl disaster, from people in nearby towns to the “liquidators” who cleaned up and built a huge concrete sarcophagus over the site. Nearly 35 years later, an international team has taken an extensive look at the disaster’s genetic effects—and the resulting pair of studies has found reassuring new details.
Allaying long-held fears over how the disaster could affect future generations, the largest study of its kind ever conducted—published on Thursday in Science—finds no evidence that parents who were exposed to Chernobyl’s radiation passed on any excess mutations to children conceived after exposure. Researchers hope the findings will benefit other populations affected by nuclear accidents, such as those displaced by the 2011 meltdown of Japan’s Fukushima Daiichi nuclear power plant.
“If there is a deleterious mutation, it’s going to be rare. We can’t say it’s never going to happen, but we don’t see this as a common public-health crisis,” says both studies’ senior author Stephen Chanock, the director of the U.S. National Cancer Institute’s Division of Cancer Epidemiology and Genetics. “We think [the findings] should be reassuring.”
“While the paper … cannot totally exclude that such effects could occur, it is clear from this study that risks are substantially lower than currently believed,” says Robert Ullrich, the vice chairman of the Radiation Effects Research Foundation, a U.S.-Japanese cooperative based in Hiroshima and Nagasaki. Ullrich wasn’t involved with the studies. “If these results can be confirmed I think that substantive changes in current risk estimates would be warranted.”
From 2014 to 2018, a team led by Meredith Yeager, a researcher at the U.S. National Cancer Institute, sequenced the genomes of 130 children who were conceived after the accident and born between 1987 and 2002, as well as the genomes of the children’s parents. The study focused on families where at least one parent had been within 45 miles of Chernobyl or had worked as “liquidators” to clean up the site.
Yeager’s team also used past data to meticulously reconstruct the radiation dose each parent had received. For instance, among the study’s fathers, their gonads had absorbed an average radiation dose of 365 milligrays, roughly a hundred times more than what they would receive in an average pelvic x-ray.
To test whether radiation had affected the children’s DNA, researchers tracked de novo mutations, or slight variations in a child’s DNA that aren’t present in either of their biological parents. These kinds of mutations occur naturally, since the cellular machinery that copies our DNA as our cells divide—including those that yield sperm and eggs—makes the occasional mistake. On average, we each carry between 50 and a hundred of these random mutations in our own genomes that distinguish our DNA from that of our parents.
In principle, if radiation had an effect, researchers would expect to see more mutations in children whose parents were subjected to higher radiation doses. But when Yeager and her colleagues combed through the families’ DNA, they didn’t see any such relationship. Instead, the biggest factor influencing the number of de novo mutations was the father’s age.
The studies also give an in-depth look at how radiation from Chernobyl fallout caused cancer in the thyroid, a butterfly-shaped gland that plays a critical role in human metabolism. Thyroid cancer is highly treatable, with a survival rate higher than 90 percent. In the first 20 years post-Chernobyl, very few people died from thyroid cancers associated with the fallout.
Past research had found that people exposed to Chernobyl fallout saw a greater risk of papillary thyroid cancers, especially among those who were young children at the time. That’s because fallout included iodine-131, a radioactive type of iodine, which entered the local food supply after settling onto fields and livestock pastures. When people ingested contaminated milk and greens, their bodies absorbed the iodine-131 and accumulated it in their thyroids. The radiation this iodine-131 gave off then damaged the thyroid cells’ DNA.
Now, thanks to advances in genetics techniques, researchers could use the Chernobyl dataset to start “figuring out how a carcinogen actually causes cancer,” says U.S. National Cancer Institute epidemiologist Lindsay Morton, the study’s lead author.
Morton and her colleagues studied tissue samples from 440 Ukrainians who had been diagnosed with thyroid cancer, 359 of whom had been exposed to Chernobyl’s radiation. The majority were female and had been living in Kiev, Ukraine’s capital, during the Chernobyl incident. They were also young: On average, they had been about seven years old at the time of exposure and were 28 when they were diagnosed with cancer.
Morton’s team also knew a lot about how much radiation these individuals’ thyroids had absorbed. For 53 people in the study, researchers back in 1986 had directly measured their thyroids’ radioactivity levels. Others were interviewed on where they lived and what they ate at the time of the Chernobyl accident, which let researchers estimate how much of a radiation dose they likely absorbed.
“This study represents the first time that we have linked such large-scale molecular pictures with very detailed exposure data,” Morton says.
The studies should inform scientists of the general health risks of ionizing radiation, especially among populations affected by nuclear accidents, such as evacuees from the 2011 Fukushima incident. Chanock expressed hope that the results would reassure people who had been displaced by Fukushima, which released a tenth of the radiation that Chernobyl did—and would theoretically pose even less of a risk of heritable mutations.
But the study’s authors, and outside experts, agree that there is more work to be done, especially to track the health effects of Chernobyl’s radiation over the decades to come.
“There are very few studies among persons exposed to radiation at young ages with follow-up data through adulthood,” says Eric Grant, the associate chief of research at the Radiation Effects Research Foundation in Japan. “The atomic bomb survivors is one such cohort, [and] the Chernobyl cohort will be another with continued follow-up efforts.”
Evgenia Ostroumova, an epidemiologist with the International Agency for Research on Cancer in Lyon, France, stressed that research on Chernobyl still needs to be funded, especially to learn more about the health consequences of low radiation doses—consequences that only more time and diligence will bring to light.
A large and advanced study of children born to parents exposed to Chernobyl radiation found no evidence of inherited genetic changes. The study also examined the relationship between radiation and thyroid cancer cases among the exposed population.
Apr 22, 2021 · Two landmark studies used genomic tools to investigate the potential health effects of exposure to ionizing radiation from the 1986 accident at the Chernobyl nuclear power plant. One study found no evidence of genetic changes being passed from parent to child, while the other study documented the genetic changes in thyroid cancers.
Apr 22, 2021 · Two studies use genomic tools to investigate the health effects of radiation exposure from the 1986 Chernobyl accident. One study finds no evidence of genetic changes being passed to children, while the other documents the genetic changes in thyroid cancers.
Feb 10, 2015 · In this paper we use a meta-analysis to examine the relationship between radiation and mutation rates in Chernobyl across 45 published studies, covering 30 species.
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