Underground waters pass through various types of rocks, which may contain radium and uranium isotopes in such concentrations and chemical forms that could be diluted in the water body. Thus it is possible to contain significant quantities of these radioisotopes such as radium (226Ra), which decays producing a series of alpha and beta emitters that remain in the water. Among them, radon (222Rn) and isotopes of polonium (214Po and 218Po) contribute to significant doses. In this work, we measured radium/radon concentration levels in bottled waters commercially available in Greece. Samples were concentrated by a factor of 20-100, in order to obtain more accurate results, because in the majority of the samples the concentrations measured initially were very low. To measure the radioactivity concentrations, 10 mL of concentrated sample were added to 10 mL of scintillation cocktail in a 20 mL plastic vial and then were counted with a liquid scintillation analyzer. The results show that radium/radon concentrations of the bottled waters range from 7-70 mBq/L.

Strontium-90 is one of the most dangerous fission products that enter the food chain. Because of its similar chemistry to calcium, it is deposited to bones posing a high risk for human health. 90Sr is a pure ^-emitter and decays to 90Y also a /3-emitter. The fast moving electrons emitted by the 90Y decay, produce Cherenkov radiation, which can be detected by a Liquid Scintillation Counter (LSC). Water and milk samples spiked with various concentrations of 9 0Sr/90Y in equilibrium were measured in a LSC (Tricarb 3170 TR/SL). The derived efficiencies were 50% for water samples and 13 % for milk samples. The minimum detectable activities (MDA) for measuring 90Sr in water and milk samples, without any pretreatment were calculated 240 mBq/L and 1 Bq/L respectively. The intervention levels for 90Sr contamination in water and milk samples, established by the European Union are 125 Bq/L and 75-125 Bq/L depending on age, respectively. The interference of 40K, which is present in milk due to its natural potassium content,was also investigated.