To put a radioactive threat in perspective, we can present its banana equivalent dose:
Many foods are naturally radioactive, and bananas are particularly so, due to the radioactive potassium-40 they contain. The banana equivalent dose is the radiation exposure received from that of eating a single banana. Radiation leaks from nuclear plants are often measured in extraordinarily small units (the picocurie, a millionth of a millionth of a curie, is typical) By comparing the exposure from these events to a banana equivalent dose, a more realistic assessment of the actual risk can sometimes be obtained.
The average radiologic profile of bananas is 3520 picocuries per kg, or roughly 520 picocuries per 150-gram banana. The equivalent dose for 365 bananas (one per day for a year) is 3.6 millirems.
After the Three Mile Island nuclear accident, the NRC detected radioactive iodine in local milk at levels of 20 picocuries/liter; a dose much less than one would receive from ingesting a single banana.
(Hat tip to Nyrath.)
I am all for tamping down radiation hysteria, and even for goodly dose of radiation hormesis (see, e.g. T.D.Lucky and others), but at the outset, one has to understand what kind of radiation is being measured.
It makes a difference (at the very least, in terms of shielding effects) whether one is measuring alpha (helium nuclei), beta (‘nuclear’ electron), or gamma (photon). What’s more important is an educated recognition of the total and destructive failure of the “linear no threshold” LNT policy for radiation (ie none — drive it to zero).
In fact, small, chronic doses of ionizing radiation are undeniably healthy. It’s up to the savvy individual to do a bit of self-education to find out how to define “small” safely for themselves — and zero is assuredly not the answer.