Radiocesium Contamination in Samples of Blueberries Jams Collected in Stores of NE Italy (2013-2017)

The monitoring of radioactivity in foodstuffs is carried out for the purposes of food safety in order to follow the evolution of the contamination as result of incidents that occurred both in the past (eg Chernobyl) and in more recent times (eg, Fukushima). Then, the movement of goods from these countries to European Union may cause the propagation of foods potentially toxic for health. At the Port of Trieste, in the period of September 2013, some loads of blueberries (Vaccinum mirtyllus L.) were examined within the application of EC Regulation 733/2008, on the conditions governing imports of agricultural products originating in the countries affected by the nuclear accident of Chernobyl in 1986. The fruits came from Ukraine and were intended for the food preparations containing blueberries, in particular jams and marmalades. As in some cases significant values of Radiocesium concentrations (Cesium-137) were found in blueberries, though below the limit of 600 Bq/kg as required by the Regulations, it was decided to verify whether the presence of this contaminant in the raw material at the tested levels could interest the finished products. In this work, we have therefore collected and analyzed some samples of concentrated blueberries products in different large stores, in order to verify the magnitude of the possible contamination by radio Cesium.


Introduction
The plant of Blueberry (Vaccinum sp.) belongs to the family of Ericaceae and is characterized by a root system called "rhizome". The rhizome grows horizontally within the first few inches of the organic layer of the soil even for many meters. It is formed by endotrophic-mycorrhiza that possess a high capacity for mobilization and absorption of mineral salts from the soil, similarly to many species of mushrooms. This property is common to all Ericacee plants and can lead sometimes to high values of radio-contamination from Cs-137.
It has already been observed in the past that the fruits of Blueberry may show concentration values of radio-cesium even greater than those recorded in different species of edible mushrooms (Zappa et al. 2001). It has been shown that the Blueberries plant can also be considered as an indicator of air pollution (Deyeva & Gerasimenko, 1994) and environmental pollution in general, as well as for other metals (Deyeva & Maznaya, 1992).
Cs-137 is considered as the more persistent tracer in the environment following cases of radiocontamination such as nuclear tests in previous years ( Fig.1) and different types of nuclear power plants accidents (e.g. Chernobyl and Fukushima).
After about 15 years from the environmental intake, the contribution to the residual gamma dose is due for almost 100% to Cs-137 nuclide (half-life 30 years). As concerns other radioactive isotopes, the most persistent synthetic isotope presents in the fall-out but at much lower level is Sr-90, with a half-life of about 29 years. Therefore, the environmental monitoring of the long-term consequences (over 15 years) of fall-out or nuclear accidents concerns the measurement of Cs-137 and, in some cases, also of Sr-90.  The produ

Material Studied
Six batches of black blueberries (Vaccinum myrtillus L.) were measured for radiocaesium at the Port of Trieste (Northern Italy) in September 2013, during the checks required on the imported food products from non-EU countries. The batches, loaded on trucks, were coming from Ukraine and directed to a food industry of the province of Bologna in the Emilia Romagna region in the middle of the Italy.
The data obtained for the specific activity for the only Cs-137 (the isotope Cs-134 is no longer detectable with the sensitivity of the used method, as the half-life is 1.9 year) are reported in the table 2. The samples analyzed showed that three of the six batches showed values lower or equal to the sensitivity limit of the method (<0.5 Bq/kg) while only in one of the lots was found a value closer to the maximum limit (370 Bq/kg) required by the EC Regulation 733/2008 for the dietetic products for children (370 Bq/kg).
For this reason, we decided to undertake the present study on concentrate Blueberries products, like jams and juices. The sampling, even if limited to a small number of products was performed in large stores both of the city of Trieste and Padua, and interested some of the most diffused trademarks of these products in Italy.

Methods and Technique
In this work, we have collected and analyzed different samples of concentrated blueberries products in different large stores.
The determination of the Cs-137 specific activity was performed by gamma spectrometry on the untreated sample, put in geometry in a Marinelli becker of 500 ml of volume. The measurement system consists of the following modules: coaxial detector with probe LaCl 3 1,5'x 1,5' 38B38 n.s. SFC-334R Scionix (Scionix Holland B.V -Bunnik, Netherlands) and multichannel analyzer. PX4-Amptek (Amptek. Inc. -Bedford (MA) -USA). The spectrometric chain is equipped with the analytical software "Amptek -Pmca" for the quantitative analysis of Cs-137 at 662 keV and was inter-calibrated with the high-resolution gamma spectrometry with high purity germanium detector systems of the laboratory ICMATE-CNR in Padua. To ensure an adequate sensitivity at the measurement, the acquisition time was set at about 42000 seconds (12 hours) for each sample. In these conditions the sensitivity limit of the method was calculated in 5.0 Bq/kg for the Cs-137.

Conclusion
The results of this work, even if limited to a small number of samples, show that in this food products Cs-137 amounts are still present in some cases at well detectable levels. For these reasons we believe it is important to maintain the control system on the interested foodstuffs (Table 1) currently prolonged by the EU Council until 2020 (Council Regulation EC 1408/2009. Even if there is no evidence of any sanitary risk, the interest of this work may concern especially the food quality. The detection of radio cesium in products defined as "organic" could suggest the use in their production, as raw material, of fruits imported from countries of East Europe, rather than the use of local controlled fruits.