back

by emptybits·3y ago·view on hn ↗
“the annual average dose per person from all sources is about 620 mrem”

That’s the mrem of 62 chest x-rays. From food and drink annually.

Should we be alarmed? Or just more comfortable with lots of diagnostic x-rays?

EDIT: Thank you. I missed a link in the article that clarifies: “From food and water (40 mrem)”

2 comments
That's not just from food and drink. Food and drink is much less, as you can see if you read that page.
From the Hacker News guidelines[0]:

> Please don't comment on whether someone read an article. "Did you even read the article? It mentions that" can be shortened to "The article mentions that."

[0] https://news.ycombinator.com/newsguidelines.html

It's okay to mention that the article says something, as your guidelines say. You're specifically not allowed to question if someone read it. Since the person you're responding to followed the "good" example you provided perfectly, I think his comment is okay.
You'll notice that chest x-ray is listed twice, the one you are referring to is a single exposure. But the chest x-ray you're thinking of is probably the latter, which is 700mrem.

Fwiw, no, you should not be concerned. An annoying thing about radiation is that the numbers are not straight forward and our measurement devices are REALLY sensitive. Rem, and Sieverts (Sv), are both dosage measurements, which means they vary based on where they interact with the body. It also changes with the type of radiation that you're exposed to. This is probably assuming whole body and gamma.

Finding numbers can also be quite hard because top google hits will be ones like this[0] which show charts for short time exposure (acute exposure). Or you get complicated ones like from the DOE[1] which calls itself "user friendly", but that's because what we discussed above. You'll notice a place in China (Yangjiang) with 600mrem, India (Kerala coast) with 1rem, and a place in Iran (Ramsar) with a bit above 15 rem! But studies consistently show that these people do not have increased rates of cancer[2,3] (if study says "less", read as "no difference"). It is worth noting that radiation safety levels are purposefully set with a high margin of safety, as measurements of an actual dose someone obtained isn't straight forward either. You may also be interested to know that astronauts (~60rem/yr) have no significant rise in cancer rates (less than 1 year life difference)[4] and in Chernobyl 134 workers got doses between 70krem and 1.34Mrem (thousand and million), and only 28 of those died (high rate, but we're talking about 10^5 to 10^7 times higher dosages than our number AND that all this is acute or chronic while our number is "evenly" spread over a year).[5] This should help give you some bounds (considering we're also including 1980's Soviet medicine for suitability rates) to help make some intuition.

For a more fun and visual comparison see here[6].

Hope this helps.

[0] https://www.atomicarchive.com/science/effects/radiation-effe...

[1] https://www.nrc.gov/docs/ML1209/ML120970113.pdf

[2] https://www.sciencedirect.com/science/article/abs/pii/S05315...

[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4674188/

[4] https://www.nature.com/articles/s41598-019-44858-0

[5] https://www.nrc.gov/about-nrc/radiation/health-effects/high-...

[6] https://xkcd.com/radiation/