Common unit used to indicate an absorbed dose of radiation. A millirem is 1/1000 of a rem. The Three Mile Island incident exposed people to about 0.005 millirems, while Chernobyl exposed people nearby to over 100 millirems. A dental x-ray is about 0.15 millirems. The average person is exposed to about 170 millirems per year, approximately half of which is naturally occuring radiation (such as cosmic rays).

A long list of radiation statistics (mostly in millirem) can be found under my node for radiation.