There are two types of doses. Chronic is when you get the dose over a long period of time. Acute is when you get the same dose in a short time and is more harmful.
For humans, an acute dose of .3 sieverts will cause blood changes, one sievert will cause radiation sickness, two will cause half the cells to undergo reproductive death, four will kill half the people exposed and ten will kill everyone.
Of course, you won't be getting anywhere near that.
Florence, if I don't need to know the scary numbers, please don't tell me the scary numbers.