Children of Chernobyl cleanup crew don’t have excess mutations | Hacker News Reader

Children of Chernobyl cleanup crew don’t have excess mutations

arstechnica.com

161 pointsrbanffy66 comments

The human body is incredibly good at detecting unviable mutations during pregnancy and it results in a miscarriage or other failures early on. This would be a much better indicator to look at than whether the children who survived pregnancy had excess mutations.

While that is also a very important indicator, what proportion of viable pregnancies produce children with mutations I would argue is an even more important metric to study.

it is an important metric if it has substance, but according to the above it has very little variance. Knowing how many pregnancies failed versus how many failed prior to the event could give us a better indicator of the damage caused.

I think the question I feel the hive mind wants to answer is, "How much radiation can the species live with and not go extinct". If the birth rates are lower and mortality right is higher we can 'make up' for that. But if the offspring accrue hereditary damage, any amount is too much.

We will have many many tough decisions to make due to the climate crisis.

And it's not just a matter of how much radiation either. Zap a bunch of fruit flies with a dose of x-rays all at once and see the next generation come out horribly mutated. Give them that same dose of radiation over the course of a month and see a perfectly healthy next generation.

Has that happened flies or animals that are immune to high radiation?

I could see the next generation having horrible mutations, I could see the genes correcting some of this in the 3rd generation. I could see some of mutations living on but resistance to radiation would be so extremely useful we would build materials out of them which we are not doing today.

That was my first thought when I saw the title. IIRC roughly 1/3 of pregnancies end within weeks, often before a woman is aware that she is pregnant, almost always because of a genetic mutation. Given that, if the miscarriage rate is higher, that would indicate that there is indeed an impact, but that our genome is very good at preventing dangerous mutations from propagating.

Another possibility is that error-correcting mechanisms are good enough to deal with whatever impact exposure to that level of radiation had. One hypothesis about meiosis and genetic recombination is that it serves as an error correcting process, where damaged genes on one chromosome can be repaired using corresponding genes from the other chromosome.

That's very true but even if these forces catch 99% of significant mutations then you'd still see an increase in pregnancies resulting from that remaining significant mutations over baseline.

But more importantly, our genomes have a lot of "junk DNA" where a mutation will not affect anything at all and almost everyone has these. From the article it looks like these were the mutations the researchers were looking at.

I remember hearing a hypothesis that "junk DNA" acts as a kind of shielding against mutations. From a probability standpoint, the more non-coding DNA you have, the less likely an error is to hurt the lifeform. Taken to an extreme, if every DNA sequence did something a singe error would cripple the organism.

However, the probability of the DNA getting hit would increase linearly with the amount of junk DNA, wouldn't it? So the chance of good DNA getting hit is exactly the same as without junk.

Not sure how it would help shielding the good DNA, unless it acted as a barrier.

Mutations from radiation come from particles literally slamming into the DNA and screwing it up. The more spaced out the important parts are, the lower the probability that the particle hits a piece of DNA that’s important.

If I place 4 cups of water out in the rain, does their spacing affect how much water lands in each cup?

It depends on how you place them, horizontaly on a table no, in a pyramid yes.

I see what you're getting at, but in this example there would be millions of cups and the individual raindrops would be spread out over a massive area of land.

That doesn’t change anything. The probability an important cup gets hit is always equal to the surface integral of the rain’s flux across the important cup openings. Whether there are unimportant cups nearby doesn’t change anything.

that makes intuitive sense but at least in the case of ionizing radiation it's a little like making a target circle bigger to protect the bullseye which remains the same size. there's still the same chance of hitting the bullseye, no matter how you change the chance of not missing the paper.

Think of it as a 3D sphere instead. You would get a shielding effect.

There is already one milligram of atmosphere over the cross sectional area of a cell nucleus, so it doesn't seem like it could change much for cosmic rays. All DNA in a human cell is about 6 picograms.

That's 166 million times more mass of atmosphere. The elements may be less effective etc. but it still seems like any junk dna shielding would be negligible.

Maybe cosmic rays aren't the main source of ionizing radiation throughout the evolutionary period though.

If the cell around is not shielding it, the little bit of extra DNA is not shielding it either. You need a lot more atoms to get a shielding effect.

I reject the term 'junk dna'. Until we understood the basics of DNA all of it was 'junk', then bit by bit we are making headway into understanding some of it. If we're ever done I predict there will be no junk DNA left. Nature is much too efficient to spend that much energy on something that it ends up not using.

> Nature is much too efficient to spend that much energy on something that it ends up not using.

And yet nature somehow finds it acceptable to grow a nerve all the way from a giraffe's head down its neck, loop around its heart and then go all the way back up through its neck until reaching the head. [0]

[0] https://rationalwiki.org/wiki/Laryngeal_nerve

Yes, and there are a number of other examples like that. But that doesn't detract from the general case in the least: if energy can be saved then it usually will be saved, especially if a mechanism lasts for a long time. The idea that the base mechanism of encoding life patterns is going to be on the order of 70% or more 'junk' requires a very good explanation. Why the argument presented here is invalid I'll leave for you to figure out.

Wouldn’t that depend on the size of the study? Seems like catching an orders of magnitude smaller difference would require orders of magnitude more samples... and the population is only so big..

“Junk DNA” as a concept is pretty dated. It used to refer to non-protein encoding regions of DNA. In our infinite wisdom we assumed these segments of DNA had no purposes yet it turns out they play an important role in DNA packing and unpacking which directly influences gene expression.

Aren't some of these early miscarriages not even known by the woman? Wouldn't that make it difficult to measure?

I was born in August 1986. In northern Poland.

I was born in the 26 pregnancy week. 40 is the avg.

Even if it was not near Chernobyl there were more miscarriage then usual.

So yes looking at the children that survived is not the correct way looking at it.

I also know that getting legit data for that is nearly impossible.

In most regions of southern Germany, many varieties of mushrooms as well as game (in particular wild boar) are still contaminated with >1k Bq/kg caesium 137 [1]. Even after 35 years (more than a half life) and Chernobyl being some 1500 km away. It's just mind boggling.

[1] https://doris.bfs.de/jspui/handle/urn:nbn:de:0221-2020093023...

The wild boars eat moss growing on trees, which is a tremendous filter for particles.

A reasonable cleanup process might be, harvest tree moss and reduce it to radioactive elements. Or just harvest the boars I guess?

To give a bit of context and relativize:

> Between September 2012 and August 2013, 297 out of 752 boars exceeded legal limits of radiation -- particularly the hazardous isotope Caesium 137, which has a 30-year half-life and decays slowly. But to give an idea of how strict the regulations really are, experts say that a person would have to eat 13 kilograms of contaminated meat to get the same low-level radioactive effects of being on a transatlantic flight.

Quote from this article from 2014: https://www.nbcnews.com/news/world/chernobyl-disaster-leaves....

> Caesium 137, which has a 30-year half-life and decays slowly

Forgive my layman's ignorance, but "decays slowly" is just a less precise version of the "30-year half-life" statement, right?

Either way it is wrong. 35 years is fast enough to not worry about long term. It only takes a couple centuries for anything with a half-life that small to complete decay. For nuclear waste we worry about things with half-lives in the thousands of years as we can't be sure we can store it for as long as it is dangerous.

The real question then becomes what does it decay into? A lot of things decay some something with a dangerously long half life.

I'm not sure I understand, are you saying we should not worry about immediate effects that only affect 1 or 2 generations?

I don't see why thinking about negative effects over different timespans should be exclusive - climate change certainly won't be an issue in thousands of years (if we still exist).

I'm saying 30 year half lifes are still considered short. We still need to worry for a few generations, but that is enough to remain in memory. If we forget about the problem in 300 years - that is 10 half lives and so it isn't a big deal. If something has a 1000 year half life it will be dangerous far longer than we can remember to watch out.

Yes, but assuming equal mass of radio active material and identical radiation output something with a half-life of 1000 years is less dangerous, radiation-wise (it still might be more poisonous)

Caesium is often brought up in this kind of discussions. I think one reason might be because it decays fast enough to be harmful and still slow enough to be harmful for considerable time.

Another reason might be that more of it gets released in your typical nuclear accident. I wouldn’t know whether that is true.

My point is about what is considered a long time, not relative dangers. Caesium is bad for a few hundred years. Some things are not as bad overall, but over the next 10,000 years is worse. Caesium in fact has been through one half life, and so is half as bad as it was at the start.

Why would there be disagreement about what is considered a long time? You are arguing that longer half life = bad, shorter half life = less bad, which misses the point.

An effect with a shorter half-life could be a lot worse/more dangerous/threatening (potentially apocalyptic) than an effect with a longer half life.

But, half-life and hazard are related as well. If atoms aren’t decaying (and spitting out alpha, beta particles or gamma rays) they aren’t much of a radiological hazard. Short-half life means more radiation hazard.

It is still contaminated because the half live is 30 years. After 35 years it is half as strong. In 350 years it will still be contaminated but it would have halved 10 times.

*300 years

They are. But you would have to eat 50 kilograms of these mushrooms to get a dose of 2 mV which is the safe annual dose for your average Joe:

> https://www.bfs.de/DE/themen/ion/umwelt/lebensmittel/pilze-w...

> https://xkcd.com/radiation/

If you’re a smoker, you’re probably exposing yourself to higher doses per year than anyone eating these mushrooms during mushroom season.

I'm not sure what you're saying. Are you saying that one needs to eat 50 kilogram of those daily to exceed the safe annual dose, or that if one eats 50 kilogram over a year, they'll have amassed more radiation from that single source than is considered safe?

If the latter, is it safe expose yourself to more than [annual dose/365] in a short time? Because 50 kg/year is just 150 gram/day, and some people eat more than that in one sitting.

Reminds me of atomic gardening, where the radiation is deliberately introduced to perform mutation breeding:

https://en.wikipedia.org/wiki/Atomic_gardening

From the abstract of Morton & al. which is one of the studies linked at the bottom:

> The 1986 Chernobyl nuclear power plant accident increased papillary thyroid cancer (PTC) incidence in surrounding regions, particularly for 131I-exposed children. [...]

> Radiation-related genomic alterations were more pronounced for those younger at exposure. Transcriptomic and epigenomic features were strongly associated with driver events but not radiation dose. Our results point to DNA double-strand breaks as early carcinogenic events that subsequently enable PTC growth following environmental radiation exposure.

You know, the feeling of surprise is the most important feeling there is. It’s a clue that somewhere in your network of facts about the world, something doesn’t fit.

Without surprise, you cannot learn anything new. Without surprise there is no change. If you are never surprised then you are stagnating.

I welcome surprise. I enjoy it. It means that tomorrow I will be smarter than I was yesterday.

What happens to a group of people when someone gets mocked or downvoted for being surprised about something? What happens in a school where you punish kids for speaking up in class with the wrong answer? Nobody speaks up. Nobody takes the risk. Everyone strives to be the same- same ideas, same stupidity. Boring. Give me surprise any day over that.

Don’t fucking downvote me for saying I was surprised. That’s how a community dies.

It must be wonderful for those of you who already know everything. But for those of us who don’t, and prefer to try to learn, don’t try to rob us of the joy of being surprised.

It should cost 1 karma to downvote.

Most communities welcome surprise, when it's signaled.

Saying "X is surprising, given Y" and then posting links to Y doesn't signal surprise. It signals "I believe that X is false and here is my evidence".

Just saw this on my twitter feed, which gives the impression that the conception date of the children could possibly affect it.

https://twitter.com/jenvcampbell/status/1386602322839674881

That would make sense. Embryos with bad genetic mutations are quite often rejected. The mother does not even have to notice this.

Thanks for sharing that, it was very powerful. I was lucky enough to be born a few years before Chernobyl, but I have a close friend who was born just after and who also has some congenital non-standard body-related "things".

Maybe it is all a coincidence, fact is many (if not almost all) of these individual stories haven't been statistically collected and analysed, it's just a "hidden continent" of very sad personal stories that will be forgotten once the affected people will no longer be alive to tell them.

Thank you for sharing this.

Anecdotal, my wife and I became parents to a beautiful baby girl in September last year. Our lil girl was diagnosed with heart disease, and ultimately we discovered she has a rare genetic disorder called Kabuki syndrome. She has many other morbidities, turns out Kabuki affects multiple systems, heart, kidney, hearing, spine, hips, endocrine, etc. We live in Gary, IN. A few years ago there was a spill in Lake Michigan from one of the steel mills. I was in the water on/around the time, because the alarm wasn't raised for a few days. My child's condition is so rare, that it took me a while to comprehend really how rare. I questioned whether the two are related. There have been studies about respiratory issues (asthma, heart disease, etc.) near steel mills. I run a local website to track our air pollution https://millerbeach.community, wish I was able to track drinking water in real-time, because drinking the same water discharged from steel mill sounds horrific.

https://www.in.gov/idem/cleanwater/resources/arcelormittal-f...

One sample can always be really "lucky."

I feel that we need to collect more data and have it open in some way so that people can look for "unexpected" correlations and figure out if people in one area or exposed to one thing are unnaturally lucky in general.

I wonder if in the future one could use purchases (e.g. harmful products which we do not know they are harmful) and GPS data (e.g. exposed to environmental factors) correlated with health records to do forensic large scale analysis? Still I wonder if the signals are strong enough to show up?

It is sort of like generic trait attribution via population studies.

I feel for her struggle, but this is disinformation.

She starts with the false claim that the Chernobyl disaster "killed hundreds of thousands of people". UNSCEAR (the IPCC of radiation) puts the death toll at 50 people, + 6000 thyroid cancers for those who were children at the time (due to radioactive iodine sticking on the thyroid) [1]. This is why folks who live near a nuclear power plant are given iodine pills: to saturate the thyroid so it doesn't use the radioactive one. This mostly useful for children.

She then attributes her defects on mutations originated from radionuclides induced DNA damage. Unfortunately there is no way to verify that claim, since there is no discernible health effect under 100mSv/year, which her parents definitely were not exposed to since they were in England.

[1] https://www.unscear.org/unscear/en/chernobyl.html

> She starts with the false claim that the Chernobyl disaster "killed hundreds of thousands of people".

This claim is repeated e.g. by National Geographic on Instagram [0]: "More than 100,000 people may have succumbed to Chernobyl-related illnesses."

[0]: https://www.instagram.com/p/COGV1yzFkO-/

Well they inserted the word “may” there so...

This is a surprising finding, given that the increased number of mutations in the wildlife around Chernobyl is well documented:

https://www.google.com/amp/s/amp.dw.com/en/nuclear-accidents...

https://www.thoughtco.com/chernobyl-animal-mutations-4155348

But, perhaps it’s because the humans were exposed for a shorter period of time before they were all evacuated.

The humans weren't eating the local (contaminated) produce, and those who stayed — due to their advanced age — and were eating it, probably weren't reproducing.

Yes, that seems likely to be a large part of it. Maybe, the takeaway is that radiation in food or taken internally is more mutagenenic than radiation externally? Or that total exposure matters more than acute exposure?

I called this a “surprising” finding and you know, surprising findings are the bedrock of discovery. Sadly I seem to have triggered a few people who can’t handle the fact that the world is an uncertain place we don’t completely understand. It must be hard to live in a world where being surprised is so threatening.

It's hard for me to see why. It looks pretty much expected that creatures that stay in contaminated areas and consume contaminated food have more mutations than creatures that don't. What's so "surprising" about it?

Well, the radiation exposure was enough to kill several of those workers outright, and the rest had hugely elevated rates of cancer. In one instance the pregnant wife of one worker spent too much time with him and the radiation emanating from his body was enough to give her a miscarriage.

And yet the article makes a very strong claim: all that radiation didn’t cause any rise in birth defects at all! That’s surprising. It certainly caused defects in the animals in the area, who didn’t have the insanely high exposure as the workers- albeit the workers were exposed for a shorter time.

So something is going on here which I freely admit I don’t completely understand.

I just thought of another possibility: all the workers who suffered that exposure were men. Perhaps, radiation on a developing fetus is mutagenic, but radiation exposure in sperm is less so, maybe the sperm that develop after the acute exposure is gone are normal!

> the radiation exposure was enough to kill several of those workers outright

I gather no wildlife took part in putting the fires off.

> the pregnant wife of one worker spent too much time with him and the radiation emanating from his body was enough to give her a miscarriage.

Did you see that in the HBO Miniseries?

"Lastly, there is the dangerous representation that, because one of the victims was radioactive, his pregnant wife endangered her unborn child by entering his hospital room. First, as discussed, none of the victims were radioactive—their exposures were almost exclusively external, not internal. More importantly, risk to a fetus from an exposure like this is infinitesimally small." [1]

[1] https://cancerletter.com/filmtv/20190524_3/

Interestingly, this is slightly contradictory to the finding that children of former radar workers have more DNMs[0]. Maybe explained by different type of radiation.

[0] https://www.eurekalert.org/pub_releases/2018-10/uob-tmi10051...

Encouraging news! What a tragedy Chernobyl was. Both in the lives lost and those forever altered by the event.

Compounded on that is also the humongous set back it contributed to for no-carbon energy. Now we are at a point where some congressional leaders are telling us the world may end in as soon 12 years[0] because of the man-made climate emergency. Since the situation is that dire perhaps the small risks of modern nuclear energy are a better alternative?

[0]: https://www.youtube.com/watch?v=oHk8nn0nw18

Why do you assume congressional leaders have any expertise that qualifies them to be taken seriously on climate issues?

Reply on news.ycombinator.com