An assessment of the (210)Po ingestion dose due to the consumption of agricultural, marine, fresh water and forest foodstuffs in Gudalore (India)

Radiological hazard assessment of 210Po in freshwater mussels (Sinanodonta jourdyi) and golden apple snail (Pomacea canaliculata) in Vietnam

210Po is a significant source of ionizing radiation that people are exposed to through food globally. This paper presents the wide range of accumulation level of 210Po in the organs of two species of shellfish including freshwater mussel (Sinanodonta jourdyi) and golden apple snail (Pomacea canaliculata), common freshwater species in Vietnam. There was a significant correlation between 210Po activity in muscle to their mass and size of freshwater mussels. In contrast, there was no relation between other organs of both species with their mass and size. The annual effective dose due to consumption of freshwater mussels ranged from 68.7 to 291 μSv year-1 with a mean value of 138 μSv year-1 for muscle and from 321 to 4560 μSv year-1 with a mean value of 1422 μSv year-1 for the hepatopancreas. Meanwhile, the AED for golden apple snail was recorded to be higher with values ranging from 105 to 2189 μSv year-1 with mean value of 673 μSv year-1 for muscle and from 468 to 4155 μSv year-1 with a mean value of 2332 μSv year-1 for hepatopancreas. Thus, the consumption of these two types of shellfish is considered relatively safe, but the hepatopancreas gland must be removed before processing.

Dose assessment for polonium-210 (Po-210) in New Zealand shellfish

Worldwide, Po-210 is an important contributor to human ionising radiation exposure through food. To characterise the ionising radiation dose for New Zealanders from Po-210 in shellfish, a dose assessment was undertaken. Deterministic and probabilistic dietary models were constructed by assigning shellfish consumption rates to Po-210 activity concentrations measured in shellfish. Modelling was undertaken for different shellfish consumer populations and geographical areas. Dietary modelling estimated an annual dose range from 4 μSv to 6070 μSv. The lowest dose was calculated for the overall shellfish consumer population residing in areas where baseline Po-210 activity concentrations were measured in shellfish. The highest dose was calculated for the high shellfish consumer population residing in areas where elevated activity concentrations were measured in shellfish. For the majority of the New Zealand population, the total estimated dose did not exceed the selected reference level of 1000 μSv, and Po-210 is therefore not a cause of concern. About 50% of high shellfish consumers residing in areas where shellfish had elevated Po-210 activity concentrations were exposed to ionising radiation resulting in an annual dose higher than 1000 μSv. Exposure assessment for different demographic groups identified that higher shellfish consumption rates in the population identifying as Māori lead to higher doses of ionising radiation for this group.

Distribution of 210Po in spice plants cultivated by conventional farming

PURPOSE

To study the distribution of ²¹⁰Po concentrations in various parts of spice plants cultivated by conventional farming in Nilgiris, South India and estimate effective radiation dose received.

MATERIALS AND METHODS

Parts of plant such as leaf, fruit, seed, flower bud and rhizome of selected spice plants cultivated at various locations in the study area have been collected for estimation of ²¹⁰Po concentration. Organic materials in known mass of processed samples have been removed by chemical method. ²¹⁰Po concentration in the digested sample has been electrostatically deposited on pre-polished silver disks at constant temperature. ZnS(Ag) detector-based alpha counting system with minimal detectable value 3.2 mBq has been used for estimation of ²¹⁰Po activity concentration.

RESULTS

Leaves of Curcuma longa have registered a high concentration of 45.6 ± 4.5 Bq kg^-1 of ²¹⁰Po and rhizome of Allium sativum has registered a low value of 4.7 ± 0.8 Bq kg^-1. Leaves of spice plants have registered higher concentration of ²¹⁰Po than their fruits, seeds, flower buds or rhizomes. Soil to plant transfer factor of ²¹⁰Po has been found to vary from 0.13 for rhizome of A. sativum to 2.23 corresponding to leaf of C. longa. Concentration of ²¹⁰Po estimated in leaves and mean leaf areas of spice plants has been found to have a correlation coefficient of 0.83, which indicates that absorption of ²¹⁰Po deposited on surface area of leaves is the main source of this isotope in plant parts.

CONCLUSIONS

Consumption of various parts of spice plant does not pose significant radiological risk as effective dose received by the general public as ²¹⁰Po has been found to vary from 6.34 to 46.05 µSv y^-1, less than the value recommended by ICRP.

210Po levels and distribution in different environmental compartments from a coastal lagoon. The case of Briozzo lagoon, Uruguay

This paper presents the levels and distribution of ²¹⁰Po in different compartments of a coastal lagoon on the east coast of Uruguay (South America). Activity concentrations of ²¹⁰Po have been obtained in different matrices, such as water, superficial sediments, clams (Diplodon sp.), freshwaters snails (Pomacea sp.), zooplankton, and fishes (Jenynsia sp.), collected at different points of the lagoon and during several sampling campaigns. In addition, the organic matter content of the sediment was determined to study the variation of ²¹⁰Po along the lagoon. The activity concentrations of ²¹⁰Po in the water samples are in the range between 1.1 ± 0.2-3.5 ± 0.4 mBq/L while in the sediment samples vary between 17.1 ± 1.4 and 540 ± 12 Bq/kg, DW. In the case of biota, the ranges obtained were 182 ± 5-265 ± 6 Bq/kg, DW in clams and 134 ± 4-1245 ± 16 Bq/kg, DW in snail samples. A good correlation of ²¹⁰Po with the organic fractions of the sediment was observed (r = 0.8798, p-value < 0.001), being obtained high values for the distribution coefficient Kd (10⁴ -10⁵). In the biota samples, a clear difference was observed in the ²¹⁰Po concentration values in both species, mainly due to the different feeding habits of both aquatic organisms, as it is reflected in the associated concentration ratios (CR). In this paper, a good set of results of ²¹⁰Po, Kd, and CR have been obtained in different matrices, enhancing the limited archives available for modelers concerning these parameters for ²¹⁰Po and freshwater systems.

Spatial variability in Polonium-210 and Lead-210 activity concentration in New Zealand shellfish and dose assessment

The activity concentrations of Polonium-210 (²¹⁰Po) and Lead-210 (²¹⁰Pb) were determined in shellfish (Perna canaliculus and Paphies subtriangulata) sampled bimonthly from March 2018 to February 2019 from 14 sites around New Zealand. Activity concentrations of ²¹⁰Po ranged from 4.7 ± 1.1 to 324 ± 17 Bq. kg^-1 with a mean value of 57 ± 72 Bq. kg^-1 (wet weight). The activity concentrations of ²¹⁰Pb were lower than those for ²¹⁰Po (0.1 ± 0.4 and 1.9 ± 0.4 Bq. kg^-1, with a mean value of 0.7 ± 0.4 Bq. kg^-1, wet weight). The calculated ²¹⁰Po/²¹⁰Pb activity concentration ratios were higher than unity in all samples indicating that radionuclides are not in equilibrium in shellfish and most of the ²¹⁰Po was unsupported by its grandparent ²¹⁰Pb. No significant difference was noted in ²¹⁰Po activity concentration between different seasons, species or shellfish condition index. Significant spatial variability in ²¹⁰Po activity concentration was observed with elevated ²¹⁰Po activity concentration in two sampling sites: Ninety Mile Beach (mean 257 ± 47 Bq. kg^-1) and Maunganui Bluff (mean 127 ± 22 Bq. kg^-1). Elevated ²¹⁰Po is hypothesised to be related to an increase of ²¹⁰Po accumulation through diet. Individuals who consume large quantities of shellfish (10 g per day or more) from areas affected by elevated ²¹⁰Po activity concentration may be exposed to an annual committed effective dose from ²¹⁰Po in shellfish in excess of 1 mSv.

(210)Po and (210)Pb in medicinal plants in the region of Karnataka, Southern India

The activity concentrations of naturally occurring radionuclides (210)Po and (210)Pb were estimated in some selected medicinal plants and soil samples of coastal Karnataka in India. The mean activity concentrations of (210)Po and (210)Pb varied in the range of 4.7-42.9 Bq kg(-1) (dry weight) and 36.1-124 Bq kg(-1) (dry weight) in the soil samples, and 3.3-63.7 Bq kg(-1) (dry weight) and 12.0-406 Bq kg(-1) (dry weight), in the medicinal plant samples, respectively. The plants, Ocimum sanctum L. and Plectranthus amboinicus (Lour.) Spreng had significantly higher activity concentrations of (210)Po and (210)Pb than other species sampled. In spite of disequilibrium between them, these two radionuclides were well correlated in both soil and medicinal plants.