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This paper presents a model of continuous exposure to 226Ra by water consumption over a 55-year period. The effects of 226Ra concentration in drinking water were investigated. Reaching the peak at the age of 16, the assessed effective dose has shown that children are more sensitive to radiation than adults. It has been found that consumption of 226Ra-rich water during certain period of life increases consequent effective doses. The earlier the exposure, the higher amount of 226Ra could be retained causing the higher values of effective dose later in life. However, long term exposure to 226Ra in drinking water as well as consumption of 226Ra-rich water during certain period of life does not indicate the appearance of malignant diseases in the year of exposure and later in adults.

Rapid screening of strontium activity in waters via Cherenkov radiation detection by ultra-low-level liquid scintillation counter Quantulus 1220 was established in two laboratories, Laboratory for low radioactivity of the Department of Physics, University of Novi Sad, Serbia (UNS) and Laboratory for measurements of low-level radioactivities at the Ruđer Bošković Institute, Zagreb, Croatia (RBI). Optimization of the method comprises choice of an appropriate vial type, selection of optimal spectral window, determination of the counting efficiency in various vials, evaluation of the influence of vial on efficiency and background. The efficiency of the measurement of A(90Sr) in plastic vials is 45.6 % and 37.3 % at UNS and RBI, respectively, while in glass vials it is lower (~32 %). Background count rate is lower in plastic than in glass vials, resulting in better counting properties of the plastic vials. The achieved minimum detectable activity for a total counting time of 300 min was 0.32 Bq∙L-1 in plastic vials at UNS and 0.34 Bq L-1 at RBI. Validation of the method was performed by determination of strontium level in spiked samples within interlaboratory comparison measurements. The A(90Sr) values determined in both laboratories did not deviate significantly from the spiked activities, giving the z-scores in the interval [-2, 2]. Only one sample at RBI had the z-score higher than 2 but lower than 3. All results from UNS had positive z-score values, including the sample measured within the IAEA proficiency test. The 90Sr/90Y Cherenkov radiation measurements of water samples can be successfully used for rapid screening of samples without any pretreatment of the samples.