American Nuclear Society

The standard worker dose limit for Japanese workers is 50 mSv/year and 100 mSv over 5 years. Before the accident, the emergency dose limit was set at 100 mSv/year but was raised to 250 mSv/year to allow workers to respond to this serious accident.
It should be noted that acute health effects are not expected at these doses to workers, although all are being closely monitored. For chronic health effects above 0.1 Sv (100 mSv), the cancer risk can be approximated as increasing by 10%/Sv.