Q: I wear my badge but don’t know what level of radiation is considered safe.
A: Safe is a relative term. There is consensus that any level of radiation exposure bears some risk. However the level varies with the type of risk, fatal cancer, genetic mutation or fetal damage, and with the amount of radiation received and the duration of exposure.
Most data on human radiation exposure has come from studies of survivors of the bombing of Japan during W.W.II. Most of this exposure was of relatively short duration and at high levels.
Crew members on the other hand are exposed to low levels of radiation over the duration of their careers. When statisticians assess the risk to crews the levels stated are based on theory. To date there is insufficient data about crew health problems to provide hard data.
One approach is to consider the limits set by the Nuclear Regulatory Commission (NRC) for radiation workers and the general public.
The NRC has set the annual limit of radiation exposure for the general public at 100 mRem. The limit set for radiation workers is 2 Rem. However radiation workers are required to wear monitors, are educated in the increased risks associated with radiation exposure and are required to keep their exposure as low as reasonably achievable. It is important to know your level of exposure and to keep it as low as possible.
Below are some of the levels set by various governmental and regulatory bodies.
NRC rec. annual limit of radiation exposure for the general public –100 mRem
NCRP rec. annual limit of radiation exposure for the general public –500 mRem
ICRP rec. limit of exposure for pregnant woman for term of pregnancy – 200 mRem
ICRP rec. annual limit of occupational exposure (5 year average) – 2 Rem (20mSv)
ALARA annual admin. limits for occupationally exposed workers – 200-500 mRem