The levels don't seem huge, and you need to be a fairly committed consumer of wild mushrooms to see a effect comparable to regular flying.

But it is interesting to note that the relevant consumer laws prevent the sale of eg. derived wild boar products from affected animals with similar contamination, which must be doing wonders for the French wild boar meat trade.

The amount of radiation from regular flying probably has no risk as well.

Aircrew have higher risk for certain types of cancers, but it's not clear if radiation plays a role in that. And of course they spend way more time on air than any regular airline customer.

https://www.cdc.gov/niosh/topics/aircrew/cancer.html

Well and as anything radiation it is always a question of how you come into touch with it.

E.g. getting hit by radiation briefly from the outside is different than having a radiation source inside your body for potentially ever (heavy metals are known to do this).

I am not sure how it is with mushrooms, but as someone who grew up in the Austrian South with similar laws regulating mushrooms I think this was the reasoning. So not that the radiation dose of one of those mushrooms would be problematic, but that it contains radiating particles that happily enter, but not so happily exit your body.

And what is the alternative explanation for the higher risk?

Contamination and aggregation via ingestion of cs137 is very different to exposure to radiation. So can one really compare them like that, is the scale aligned?

Yes, that's the intent of the unit: https://en.m.wikipedia.org/wiki/Sievert

For context, you get 6 mSv per year from natural background sources plus normal medical diagnostics in the USA. In Denver you get 9 per year due to proximity to space (cosmic rays ..). In Ramsar Iran the population gets 150 mSv/yr due to higher natural radiation in the local geology.

Regular consumption of these mushrooms leading to an additional 0.27 mSv doesn't concern me even a little.

All publications and news discussing radioactive contamination should be required to be quantitative in mSv units like this one. The difference between detectible and hazardous in radiation is about 10 orders of magnitude.

https://www.epa.gov/radiation/radiation-sources-and-doses#av...

More dose info; https://www.energy.gov/sites/prod/files/2018/01/f46/doe-ioni...

Bananas are 0.1 microsieverts, interestingly enough.

I just wanted to quickly highlight the difference in units in the parent and the grandparent: 0.1 uSv vs 0.27 mSv (i.e. three orders of magnitude).

So if you ate a banana a day you'd get 0.0365 mSv of primordial K-40 radioactive contamination per year! Gasp. ;)

Adding to this, here [1] is a calculator to get some rough numbers for exposure. It isn't perfect or all-inclusive but covers what I was looking for that being altitude differences

[1] - https://www.ans.org/nuclear/dosechart/