Officials have stated that the health risks are quite low as so far very small amount of radioactivity has been released into the environment.
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Radiation damages DNA and can kill cells. DNA damage can cause cancers, like leukemia and cancer of the kidneys and liver. Also depending on the type of radiation that is released, it can linger in the environment for thousands of years. The initial symptoms of radiation poisoning are nausea and vomiting, while exposure to higher radiation can cause diarrhea, headaches and fever. Depending on the level of exposure people might develop symptoms 1-4weeks later, like hair loss, vomiting, disorientation, fatigue, dizziness, infection, poor wound healing and low blood pressure.
Source-Medindia