A Japanese citizen (Tatoo artist) tweeted that he measured beta ray from chocolate.
The chocolate is a type of snack in a tube, made in Ishioka, Ibaraki.
The background radiation (beta ray) was 0.000 microSv/h.
It picked 0.004 microSv/h on the chocolate. The max reading was 0.005 microSv/h.
It is likely to be from strontium contained in the chocolate.
The person who conducted this measurement analyzes water in eastern Japan is contaminated already.
Following up test is expected.