The linear no-threshold model extrapolates cancer risk observed at moderate and high doses straight down to zero, assuming any dose carries some proportional risk. It underpins dose limits, collective dose and ALARA. Its accuracy below roughly 100 mSv is scientifically debated because effects there are too small to measure directly, but regulators keep it as a prudent and workable basis for protection.
Under LNT, that 2 millisievert still carries a theoretical risk, which is why we still bother to shield it.
Arguments about LNT surface in every break room; in practice it changes nothing on the job, because ALARA applies either way.
Also heard as
- linear no-threshold
- linear non-threshold model
Related terms
Stochastic effects
Radiation effects, chiefly cancer, whose probability rises with dose but whose severity does not.
ALARA
As low as reasonably achievable: the principle of keeping doses as low as practical, not just below limits.
Collective dose
The sum of individual doses received by a group of people, in person-sievert or person-rem.
Dose limit
The maximum dose a worker or member of the public may legally receive from regulated sources in a set period.