In tsunami-hit Japan, "safe radiation dose" is one of the frequently used terms by pundits after the explosion at Fukushima nuclear plant. Safe radiation dose is the quantity of radiation that humans can be exposed to without getting injured.

Former Secretary of Atomic Energy Regulatory Board, an expert on Radiation Protection, KS Parthasarathy, asserted that according to the board, annual dose for people who are working at the reactor site should be as small as reasonably feasible.

"It should not exceed 30 millisievert (mSv) excluding the dose due to natural background radiation and medical exposure, if any... AERB dose limit at 30mSv is lower than 50 mSv prescribed by USA", said Parthasarathy.

He said that while recovering a lost radiation source used in industry, he himself has received around 0.9mSv, while during Fukushima nuclear emergency procedures one worker received 106mSv.

He further explained that the limit of the dose for general public is mSv and in case of pregnant women the dose should not exceed 1mSv.

On the other hand, during medical treatment the following dose in mSv may be considered as safe and acceptable: treatment of hyperthyroidism 100,000, the radiation treatment of cancer 60,000 mSv to the part of body. The limit of dose for an astronaut in USA is 250mSv per operation.

According to World Nuclear Mission (WNA), an exposure to 10,000mSv in a single dose can lead a person to death by causing temporary radiation sickness, including nausea and vomiting.