Everything written above are facts, not opinions.
They are little known facts, which is why I have mentioned them. Uranium and thorium are the most radioactive among the elements that have survived since the creation of the Solar System, but they are not the only radioactive primordial elements, there are many others.
Most people who are afraid of radiation do not realize how many of the surrounding objects are radioactive, without being dangerous because of that.
Of course, you are correct that the dangers of radioactivity depend on the dose. But your message is diminished by overly emphasizing the radioactivity in carbon and other naturally occurring elements that pose zero health risk and frankly are so very non-radioactive in a relative sense.
Whenever at least one isotope is radioactive, anything containing that element is radioactive, but with a lower activity, proportional with the natural abundance of the radioactive isotope. Because the isotopic abundance also matters, elements like carbon and potassium have very low activities even if their radioactive isotopes have high activities, because the abundance of their radioactive isotopes is very low.
The majority of the naturally occurring chemical elements, i.e. about three quarters of them, are non-radioactive.
Even if the naturally occurring chemical elements either are non-radioactive or have low radioactivity, otherwise they would have disappeared since the formation of the Solar System, their radioactivity is non-negligible due to the huge number of atoms that exist in every gram of substance.
Inside a human body, during each second, thousands of atoms disintegrate, emitting radiation.
However, almost all damage caused by the natural radiation is repaired, because all living cells have very efficient mechanisms for this. Only at higher doses those are overwhelmed.
I think you the defintion is the opposite, ie that an element is considered radioactive if NO isotopes are stable (ie ALL are radioactive).
https://www.thoughtco.com/list-of-radioactive-elements-60864...
Huh? Care to name 5 non-radioactive elements according to your definition?
> [we have it in our body], so... [we all are radioactive]
can be radioactive in some circumstances, does not mean they are always radioactive. Is a non-sequitur.
There are no circumstances that can influence its radioactivity, short of placing it inside a nuclear explosion or inside a high-energy particle accelerator.
Nevertheless, most naturally occurring radioactive elements have a radioactivity that is low enough to not pose any danger.
> There are no circumstances that can influence its radioactivity
False and false. Elements are not radioactive per se. Only some isotopes of those elements are, and some are more frequent than other. Just because you have some carbon in your body does not mean that is radioactive. (In some cases metabolism even evolved to favor some kind over the other).
Time can and will influence radioactivity, so any radioactive element is -not- always radioactive. This is false.
Location is also very important. The background radioactivity of a granite mountain is not included in the body as atoms. It does not pass the outer skin barrier, that is shedding a layer of dead cells all the time in any case.
Obvious half truths and misdirections told in a really arrogant way then re-enforce the idea that anyone telling them any amount of radiation is safe is deliberately trying to mislead them, and so they wind up trusting nobody.
They then correctly infer that the liar is malicious and trying to scam them. So all in all they get to the right place even if it is for the wrong reasons.
Despite that, our body contains large quantities of them.
Like also for the chemical toxins, the dangers of radiation depend on the dose, and we should not worry when it is low enough.
Also platinum is a radioactive element, but those who wear platinum jewelry are seldom aware of this.