The Scottish Environment Protection Agency (Sepa) revealed that traces of iodine-131 have been found across the country.
Almost all air samples taken from its sites in Scotland have shown “very low levels” of iodine-131, which comes from the plant that experienced explosions after an earthquake and tsunami devastated north-east Japan last month.
Grass samples taken from around Scotland have also shown traces of radioactivity, as has a freshwater sample in Caithness and a rainwater sample.
Sepa claim that the levels found did not pose any risk to the public.
A spokeswoman said: “The concentration of iodine-131 in these samples is of no concern to human health and all of the concentrations reported to date are below the levels where regulatory control is necessary.
“Sepa will continue to monitor the environment, including sampling air, water, food, milk and grass, and will provide the information to the public and, where appropriate the Food Standards Agency, Scottish Water and the Drinking Water Quality Inspectorate.”
Iodine-131 was also found by the agency in sewage sludge in Glasgow.
The source of it is believed to be a combination of the isotope in rainfall, together with authorised releases from hospitals in the city.
Soil, other freshwater samples, cow and goats milk have all been analysed by Sepa, but to date, they have not shown the presence of detectable levels of iodine-131 from Fukushima.