There are many other radioisotopes in the body in addition to those listed above.Most of those omitted contribute very few decays per second, and are thus trivial compared to those in the table.These include familiar isotopes that are found in the fallout from nuclear weapons, such as Cesium-137 and Strontium-90.
The fact that they are still present in our environment is due to the fact that their half lives are comparable to the age of the earth, and thus they have not yet decayed into stable elements.
Three of the above listed isotopes, Lead-210 (C), are both continuously being created by cosmic rays in the earth's upper atmosphere.
Today, much of the Tritium in the atmosphere is manmade in nuclear reactors, but prior to the nuclear era the only source of H was cosmic ray bombardment of carbon.
Does this imply that every time a radioactive atom decays in the body a cancer results?
Or does it mean that once in a while such an event may cause a cancer?
The statement is meaningless without an estimate of the risk per event.
Let's consider the source of the nearly 8000 radioactive events that take place in our bodies every second.
In spite of the frequently stated phrases that "all radiation is harmful" and that "there is no safe dose of radiation", we humans contain, survive, and thrive with rather remarkable quantities of radioactive materials in our bodies.
This is not unexpected, for we do live on a somewhat radioactive planet.