engleski

Radiostrontium Contamination of Milk in the Republic of Croatia

Milk is the sensitive indicator for presence of fission products in the environment. In addition, milk as the very important foodstuff in dietary habits is potentially a major source of radioactive contamination by ingestion. Since the days of intensive atmospheric nuclear weapon tests, dairy milk in Croatia has been continuously collected and analysed for radioactivity. In this paper are summarized the results of long-term systematic measurements of radiostrontium activities in milk. Milk samples from Zagreb dairy, 1 L every day, were obtained commercially. In 1960s 90Sr was determined by the conventional radiochemical analysis with fuming nitric acid separation. From 1970 to present 90Sr was determined by extraction with tributyl phosphate, except in the year of the Chernobyl nuclear accident, when fuming nitric acid was also used. Fallout activity affects milk activity, the coefficient of correlation being >0.9. The radiostrontium activities in milk in Croatia are log-normally distributed, reflecting the exponential decrease of activity. The nuclear accident in Chernobyl did not cause any significant increase of 90Sr activities in environmental samples in Croatia, including milk. The dose due to radiostrontium ingestion by milk consumption was estimated for the Croatian population (approximately 4.8 million of inhabitants). The annual collective equivalent dose in the year of Chernobyl was 5.5 manSv.

radioastrontium; milk; fallout

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