Radon gas is a well-known source of natural radiation in the living environment. Radon is a radioactive isotope of the uranium family, and it is a gas that seeps out of the rocks and concrete used as structural materials in buildings. Since Japan has many wooden houses and few basements, it has been thought that Japanese people are not exposed to much natural radiation.

Recently, however, it was discovered that the seafood that Japanese people consume in large quantities contains a large amount of polonium, a radioactive isotope in the same uranium family. This means that Japanese people have been unknowingly affected by natural radiation from the uranium series (Polonium-210: 0.80 mSv/year in Japan). This is an example of low dose with a long time of exposure, but it has not had a negative effect on the relatively long life expectancy of the Japanese. At least, I've never heard of people who don't like seafood living longer, and it's not an obvious correlation like smoking.

agree

DearKengo Shibuya

Thanks for your interesting answwer, I appreciated it

In Poland, we have regions of the country where radon is more concentrated, but this is not a big problem. Designers know about it, typical building designs made mainly of concrete show sufficient tightness in relation to the possible hazard. Especially that due to the presence of water in the ground and its rise in the layers above the ground level (even temporary), continuous insulation of foundations and underground parts in general is always used. The basements are usually ventilated.

Dear Dr. Piotr Knyziak

I appreciated your comment. So the accepted levels of the radon gas relatively different regraded to the ventilation rate.

The best

The basic protection against radon is the tightness from the foundation side, however, it may become unsealed over time. Good ventilation ensures a low concentration of radon in the case of possible penetration into the interior of the building.

Dear Dr. Piotr Knyziak

Thanks for your interesting comment

The "accepted" levels of exposure are always what Governments want. Why? Well, businesses would be shutdown if tolerances were too strict.

With that said, most exposure recommendations, throughout the electromagnetic spectrum, mind you, are for short-term exposure levels and risks. Long-term affects are not able to be properly correlated to a "cause," because there is so much pollutants in our society that one would never be able to link an affect, say cancer, to exposure of one specific compound or element.

Kengo Shibuya shows us that polonium, which is totally unnatural, to be in the seafood we eat; moreover, polonium is considered one of the most toxic substances to be exposed to, yet people seem to be "living" with the pollution just fine. I would disagree with Kengo's thesis of "living just fine with one of the world's most toxic substances." I feel the long-term exposure to polonium -- and other pollutants, like micro-plastics -- are absolutely detrimental to human health & safety. We know cases of cancer, autism, &c, are on the rise and something must account for that phenomenon.

It's tough, but it's the way it is...

Cheers!

Dear Luisiana Cundin,

Thank you for your valuable mentions regarding my comments. There is a difference between radiation and microplastics.

Radiation is universal in nature and we have been dealing with it since we were primitive amoeba-like organisms. It is also known to have triggered the important evolution of several genes, and it is presumed that organisms have used radiation well, or that species that have been able to use radiation well have survived. And humans are one of those species.

Microplastics, on the other hand, do not exist in large quantities in nature. It is unknown whether our genes are programmed to deal with it.

What do you mean by "the accepted level of radiation exposure dose"? Occupational or public dose limits (in effective dose for stochastic effects, in equivalent dose for tissue reactions/deterministic effects) represent the maximum dose that would be "accepted" by regulatory authorities in planned exposure situations.

Annual effective dose from natural background radiation is 2.1 mSv/year in Japan, which is slightly below the world average of 2.4 mSv/year. Both in Japan and on the world average, internal exposure contributes more greatly to effective dose than external exposure. The level of effective dose posed by internal exposure in Japan (1.47 mSv/year) is comparable to that on the world average (1.55 mSv/year). What is different for internal exposure in Japan vs the world average is ca 3 fold higher contribution of ingestion (0.99 mSv/year in Japan of which ca 80% is accounted for by 210Po and 210Pb in seafood, vs 0.29 mSv/year on the world average) and ca 3 fold lower contribution of inhalation (0.48 mSv/year in Japan of which ca 80% is accounted for by 222Rn and its progeny, vs 1.26 mSv/year on the world average).

210Po is a naturally occurring polonium radioisotope, which contributes to internal exposure via ingestion of seafood and tobacco smoking.

Nobuyuki Hamada

An excerpt from Wikipedia:

"210Po is extremely toxic; it and other polonium isotopes are some of the most radiotoxic substances to humans.[6][16] With one microgram being more than enough to kill the average adult, 210Po is 250,000 times more toxic than hydrogen cyanide by weight;[17] it is also thought that one gram of 210Po is enough to kill 50 million people and sicken another 50 million.[6] This is a consequence of its ionizing alpha radiation, as alpha particles are especially damaging to organic tissues inside the body. However, 210Po does not pose a threat outside the body, for alpha particles cannot penetrate human skin.[6]"

Yes, I'll admit, it is naturally occurring, but normal concentrations should be trace amounts. Plutonium is definitely not natural and every living human has plutonium in their system in trace amounts. The source? All nuclear tests conducted in the atmosphere during the 1950s through the 1960s.

Asaad Hamid Ismail is asking for the long-term risks from exposure to radioactive isotopes. These "heavy metals" are absorbed into or bodies and never leave, so, over time, one accumulates the total amount of toxins in their body. Asaad is correct in thinking and questioning the "standard" model with regard to radiation exposure and human health & safety.

A bit more:

Article Trace Elements Contamination and Human Health Risk Assessmen...

https://www.medicalnewstoday.com/articles/58088

The two above explain the severity of Polonium-210 in the human body.

Best

Effective dose has taken into consideration of high biological effectiveness of alpha particle emitters, with a radiation weighting factor (wR) of 20. The large majority of ingested plutonium is not absorbed into the body, although absorbed plutonium stays in liver and bone for decades with biological half-life depending on chemical forms.

Dear colleagues. Thanks for all of your interesting comments

My pleasure, Dr Asaad Hamid Ismail .