In total we analysed bone samples of 88 patients. The group of Southern Poland inhabitants contained 60 people, 20 men, 37 women, and 3 person whose gender had not been specified in the questionnaire. The youngest patient was 41 years old, while the oldest 88. For Northeastern Poland bones 28 people were involved, 11 of them were men and 17 women. Their age ranged between 32 and 90. The obtained concentration ranges for the studied isotopes in booth populations are presented in Table 3. In all the samples 238Pu activity was found to be below the minimum detection activity concentration, that is on the level of a single mBqkg−1. The completed results for booth group are presented in Table 4. It is noticeable that the data presented in Tables 3 and 4 do not show any significant differences for the studied isotopes concentration in bones between the members of both groups.
Next, we tried to find correlation between the studied isotopes concentration and the patients age. The obtained correlation results are presented in Figs. 2, 3 and 4. For Pu and Am one can see an increasing trend, the older the person was, the higher activity Pu and Am concentration were found. This was observed already for a smaller group of 28 analysed human bone samples . On the contrary, for Sr such a trend could not be observed. As the main pathway of Pu is inhalation, the increasing trend may suggest that the observed Pu was systematically accumulated over the patient‘s life. On the other hand, in Fig. 5 we can see a difference between a child patient at 1970 and the rest of the investigated people. It is generally known that after 1963 the USA, Soviet Union and UK stopped their atmospheric weapon tests, thus Pu concentration in air kept falling down smoothly over the next years by orders of magnitude. This difference can be explained by much less lungs air exchange efficiency in children. Moreover, the increase in the activity concentration with age can be also interpreted in terms of losing bones mass while aging—the bone mass is in the denominator and keeps diminishing. Therefore, the increasing trend is of solely spurious nature as the observed concentration had been accumulated mainly in the fifties and sixties of the last century, when the number of atmospheric tests reached its maximum.
Correlation between Pu and Am concentration was also analysed (Fig. 6). The coefficient of trend line equal to 0.26 is very close to the model ratio between activity of 241Am and 239+240Pu for the global fallout, i.e. 0.33. This may suggest the global fallout to be the main source of contamination in examined humans.
The mass spectrometry range obtained for Pu ratios in both populations are presented in Table 5. Table 6 shows the range of Chernobyl fraction. The mass ratios and the Chernobyl fraction for each sample are presented in Table 4. Pu mass ratio for each sample are also presented in Figs. 7 and 8. As we can see in both populations the majority of the samples display ratios characteristic for the global fallout. In several samples we also found very unusual relatively low ratios that may suggest nuclear weapon construction materials to have participated into it. We did not manage to formulate a good explanation to it. Chernobyl fraction in both population tends to be marginal. More than a half (56 %) of all the results showed Chernobyl fraction to be below 5 %. Only in two samples Chernobyl fraction above 10 % was detected.
The current results can be compared to the existing data on Pu content in human bones. Table 7 presents such a comparison for activity concentration range of bone-seeking isotopes obtained currently with a set of examples to the data already existing [13, 22–28]. Apart from cases where bones of accident victims were examined, the obtained results are very similar to the ones reported previously for a worldwide population.
A more complex statistical studies, such as correspondence analysis, were preformed to find any relationship between the observed activity concentration and certain properties, or individual habits reported in the questionnaire. The results were already published elsewhere, in the proceedings of a local conference , nevertheless it worth quoting that among different parameters used in correspondence analysis, the strongest relationship between the high levels of activity concentration of 241Am and 90Sr in bones, and intense cigarette smoking and declared high level mushrooms consumption was found. It is also worth highlighting that higher levels of activity concentration of 241Am and 90Sr in bones correlated with patients’ age range 61–73 year, which is in accordance with the above hypothesis that these patients incorporated the majority of radioactive contamination during their childhood, i.e. in fifties and sixties of the twentieth century.