Concentration levels of 210Pb and 210Po in dry tobacco leaves in Greece.

Tobacco leaves are large and have sticky exudates that retain the radon decay products once they deposit on the leaves. The study of 210Po in tobacco is required, because of the cumulative alpha-radiation dose delivered to humans from inhaled 210Po in cigarette smoke. 210Pb is the other element of interest since it is the 210Po precursor in the radioactive decay chain. In the present study, the concentrations of these two radionuclides were determined in tobacco samples from seven regions in Greece. 210Po was determined by alpha spectrometry using a surface barrier detector after radiochemical separation and spontaneous deposition of polonium on a nickel disk. The 210Pb activity in the samples was determined via the 210Po resulting from the decay of 210Pb. The results of the present study indicate that 210Po concentrations ranged from 3.6 to 17.0 mBqg(-1) (average 13.1 mBqg(-1)) of dry tobacco, while 210Pb concentrations ranged from 7.3 to 18.0 mBqg(-1) (average 13.4 mBqg(-1)). The mean value of the annual committed effective dose for smokers (20 cigarettes per day) of Greek tobacco was estimated to be 287 microSv (124 microSv from 210Po and 163 microSv from 210Pb). The inhalation dose for smokers is on average about 12 times higher than for non-smokers living in the mid-latitudes of the northern hemisphere.

Determination of uranium and radon in potable water samples.

In this work, potable water samples collected from boreholes of the Migdonia valley, located NE of the city of Thessaloniki, were analyzed for the determination of uranium (238U) and radon (222Rn) concentrations. The objective of the present work is to examine if there is any correlation between radon and uranium concentrations in the water samples. For the determination of traces of uranium in water samples, an analytical technique was developed based on the selective adsorption of uranium on the chelating resin, SRAFION NMRR, and the in situ determination of the retained uranium by instrumental neutron activation analysis (INAA). By the described procedure, it was possible to determine uranium amounts in the range of microg/l. For measuring radon in water, a liquid scintillation counting system, using the Packard protocol was employed. The measured 222Rn activity concentrations are from background level up to 160 Bq l (-1).

Radon in public water supplies in Migdonia basin, Central Macedonia, Northern Greece.

The main objective of this work is the accurate measurement of radon concentration in the public water supplies of the Migdonia basin in Northern Greece. The main aim is to localize the sub-areas that present high radon concentrations in water and to inform the local authorities so that more detailed studies might be set up in these areas. About 80 samples from special bore holes and taps that supply the local population with fresh water were collected in order to obtain detailed radon measurements. For the analyses, a liquid scintillation counting system, using the Packard protocol for measuring radon in water, was employed. The results of the investigation show that radon concentrations in these public water supplies are significant. The concentrations ranged from background concentrations to 170 Bq x L(-1). The level of 50 Bq x L(-1) is exceeded in 23% of water supplies. These preliminary results with initial data interpretation and inter-comparison assessment are presented. These results of the analyses showed that elevated radon concentrations were detected in water samples from an area at the western part of the Lake Volvi, due probably to the local intense tectonism, and from a village above the Lake Koronia.

Strontium-90 activity in monthly milk samples from Greece.

The present study evaluated after the Chernobyl nuclear accident the activity of 90Sr in commercial bovine milk sampled monthly from 1987 to 1994. Monthly mean activities (0.04 to 1.25 Bq/L) were comparable with those reported for other countries of the European Union (0.05 to 0.9 Bq/L), but maxima were higher, and the range of values was wider. Milk samples were also compared against samples of bovine milk in Greece that were collected before the Chernobyl accident during the period from 1969 to 1983 (0.04 to 1.37 Bq/L) and from 1985 to 1986 (0.04 to 0.30 Bq/L). The data were fit exponentially utilizing the chi-square statistic. The goodness of fit for the curve was 65%. Based on this result, the effective half-life of 90Sr in milk was estimated to be 308 +/- 57 d, which is very short compared with the physical half-life of 10,410 d for 90Sr. Since the second half of 1992, the decay curve of the measured mean activity approximated a threshold of 0.09 +/- 0.03 Bq/L, which is close to the low limit of detection by beta-scintillation.