Radioactivity in grain and bread

Cereal grain samples are collected annually from ten Danish experimental farms. The samples are analysed for contents of ⁹⁰Sr and ¹³⁷Cs. Concentrations of both of these radionuclides have overall declined steadily since the cessation of the large atmospheric nuclear tests in 1963. When contamination released by the Chernobyl accident deposited on Danish fields in late April and early May 1986, winter grain plants had reached a quite high state of development. The direct deposition on the plants thus led to significant incorporation of contaminants, which was reflected in a 43 times higher mean radiocaesium grain contamination level in 1986 compared with the previous years. The following year, when the radiocaesium incorporation occurred solely through plant root uptake, the grain contamination levels were generally more than an order of magnitude lower. ⁹⁰Sr deposition after the Chernobyl accident had too low concentrations to significantly affect the ⁹⁰Sr levels in harvested grains, which have since the early 1980’s declined with an effective half-life of about 10-15 years. It should be noted that flour generally contains lower concentrations of radionuclides than the whole grain, whereas bran contains higher concentrations.

Radionuclide concentrations in rye and wheat are shown together with the corresponding concentrations in respectively rye bread and whitebread. Good correspondence is seen between the grain and bread concentrations, keeping in mind that a fraction of the flour is applied in the following year.

	Strontium-90 in rye collected in 1959-2008 and in rye bread collected in 1962-1990
	Strontium-90 in barley collected in 1959-2008
	Strontium-90 in wheat collected in 1959-2008 and in whitebread collected in 1962-1990.
	Strontium-90 in oats collected in 1959-2008
	Caesium-137 in rye collected in 1962-2008 and in rye bread collected in 1963-1991
	Caesium-137 in barley collected in 1962-2008
	Caesium-137 in wheat collected in 1962-2008 and in whitebread collected in 1963-1991.
	Caesium-137 in oats collected in 1962-2008.

Page updated by 25.08.2009

Kasper Grann Andersson
Senior Scientist
Radiation Research (NUK)
Dir tel+45 46774173