Baseline concentration of 210Po in Kuwait's commercial fish species

Factors Contributing to Accumulation of 210Po in Freshwater Fishes in Dong Thai Lake, Vietnam and Radiological Hazard Assessment

210Po (polonium), one of the most toxic naturally occurring radionuclides, is well-known as a common natural radionuclide in fish species. Human consumption of 210Po-contaminated fish could result in a significant internal dose. This study determined by alpha spectrometry the 210Po activity in sixteen selected fish species with different living behaviors (pelagic, demersal), trophic positions (herbivores, carnivores, omnivorous), and masses in Dong Thai Lake, Hanoi, Vietnam. The min, max, and average of the 210Po concentration of sixteen fish species were 0.80 ± 0.44, 12.7 ± 0.20, and 3.54 ± 0.31 Bq kg-1, respectively. Regarding the different living behaviors, trophic positions, and masses, the results showed trending of 210Popelagic > 210Podemersal; 210Poherbivores < 210Pocarnivores < 210Poomnivorous and 210Po<0.2 kg > 210Po0.2-1 kg > 210Po>1 kg, respectively. The 210Po concentrations in muscle tissue were greater in fish species with a small mass, omnivorous trophic position, and pelagic living behavior relative to demersal fish with a larger mass that were herbivores or carnivores. In addition, the results showed an uneven distribution of 210Po activities in atmospheric aerosols, terrestrial soils, surface waters, and lake sediments in the study area. The primary source of 210Po could be supplied from atmospheric aerosols and/or terrestrial soils in the study area. The 210Po annual effective dose for adults due to fish consumption has been calculated with a range from 20 to 400 µSv y-1 and 111 µSv. y-1 on average, and it is far below the allowable limits of 1000 µSv y-1.

Characteristics of 210Po in Asian overbite clam (Potamocorbula laevis) from the coastal area at Thai Binh province, Vietnam

210Po concentration in the edible muscle tissue and digestive diverticulum organs of Asian overbite clam at the near-shore Thai Binh, Vietnam was analyzed using alpha detectors. The 210Po activity in muscle tissue and digestive diverticulum organs ranged from 5 ± 1 to 178 ± 10 and from 118 ± 7 to 812 ± 12 Bq.kg-1 with the average value of 25 and 324 Bq.kg-1, respectively. Results showed that 210Po activity in the digestive diverticulum was significantly higher than in the muscle tissue. There was a slightly inverse correlation between 210Po activity in muscle tissue, digestive diverticulum, and clam weight and size. The annual committed effective dose was calculated from 210Po due to the consumption of Asian overbite clam for adults in the study area was higher than the guideline value of 0.2 - 1 mSv.y-1.

Ocean Acidification-Mediated Food Chain Transfer of Polonium between Primary Producers and Consumers

Phytoplankton and zooplankton are key marine components that play an important role in metal distribution through a food web transfer. An increased phytoplankton concentration as a result of ocean acidification and warming are well-established, along with the fact that phytoplankton biomagnify 210Po by 3−4 orders of magnitude compared to the seawater concentration. This experimental study is carried out to better understand the transfer of polonium between primary producers and consumers. The experimental produced data highlight the complex interaction between the polonium concentration in zooplankton food, i.e. phytoplankton, its excretion via defecated fecal pellets, and its bioaccumulation at ambient seawater pH and a lower pH of 7.7, typical of ocean acidification scenarios in the open ocean. The mass of copepods recovered was 11% less: 7.7 pH compared to 8.2. The effects of copepod species (n = 3), microalgae species (n = 3), pH (n = 2), and time (n = 4) on the polonium activity in the fecal pellets (expressed as % of the total activity introduced through feeding) was tested using an ANOVA 4. With the exception of time (model: F20, 215 = 176.84, p < 0.001; time: F3 = 1.76, p = 0.16), all tested parameters had an impact on the polonium activity (copepod species: F2 = 169.15, p < 0.0001; algae species: F2 = 10.21, p < 0.0001; pH: F1 = 9.85, p = 0.002) with complex interactions (copepod x algae: F2 = 19.48, p < 0.0001; copepod x pH: F2 = 10.54, p < 0.0001; algae x pH: F2 = 4.87, p = 0.009). The experimental data underpin the hypothesis that metal bioavailability and bioaccumulation will be enhanced in secondary consumers such as crustacean zooplankton due to ocean acidification.

Evaluation of the radiological dose due to 210Po in commercial clupeid fish collected in the near-shore environment of the high background natural radiation area (HBNRA) on the southwest coast of India

In this study, we quantified the tissue concentration of ²¹⁰Po in a variety of commercial sardine fish species of the family Clupeidae from an area of high background natural radiation area on the southwest coast of India. The smooth belly sardine Amblygaster leiogaster had the lowest ²¹⁰Po concentration in its muscle (45.6 ± 7.9 Bq kg^-1 fresh), while the goldstripe sardine Sardinella gibbosa had the highest (103.4 ± 10.1 Bq kg^-1 fresh). The Annual Committed Effective Dose (ACED) of fried sardine and sardine curry were 134.3-304.3 μSv y^-1 and 226.6-513.5 μSv y^-1, respectively. Of the ²¹⁰Po loss, 20 % was due to frying and 10 % to preparing sardine curry. The effective dose was found to be globally comparable and well below the world limit. Consumption of sardines containing ²¹⁰Po would not pose a health hazard to the residents of Manavalakurchi.

Gross beta and alpha activities in the selected commercial freshwater fish species in Vietnam

The baseline data of radioactivity levels in food is one of the main factors for the assessment of resident's health risk. Gross beta and alpha activity was identified for selected commercial freshwater fish species, including 29 types of fish species by a gas-flow proportional detector. The samples were collected from wholesale markets in Hanoi city, Vietnam. The highest gross alpha activity was recorded in blotched snakehead, a pelagic and carnivorous species, and the lowest one was recorded in common carp, a demersal and omnivorous species. Meanwhile, the gross beta activity was much higher than the gross alpha activity with the highest value of gross beta, observed in Wels catfish, a demersal and carnivorous species, and the lowest one found in Mudskipper a demersal, herbivores species. Regarding feeding types, the gross alpha activity was observed in the order of Al_carnivores > Al_omnivores > Al_herbivores whereas the gross beta was non-distinction. In terms of living behavior, the gross alpha activity in pelagic species was much higher than that in demersal species (Al_pelagic >  > Al_demersal) and indifferent for gross beta. There was an insignificant relationship between the trophic level with gross beta and alpha activities in freshwater fish species. The calculated annual effective dose ​​ranged from 0.19 to 1.88 and 0.78 mSv.y^-1 on average, being within the limited dose for the public as reported by UNSCEAR in which gross beta activity has a strong correlation with the total annual effective dose.

Distribution and annual committed effective dose assessment of 210Po in popular marine species at the near-shore Binh Thuan province, Vietnam

²¹⁰Po concentration in thirty popular marine species (twenty five fishes, four bivalves and one crab) with different habitats, feeding types, and trophic levels at the near-shore Binh Thuan, Vietnam was analyzed using the alpha detectors. The ²¹⁰Po activities were widely ranged from 3.07 ± 0.18 in a fish species (Bumpnose trevally) to 78.6 ± 5.3 Bq/kg w.w in a bivalve species (Green mussel) with the average value of 16.6 Bq/kg w.w. The results showed that the species with lower trophic level value have higher ²¹⁰Po concentration. Regarding the feeding types, the ²¹⁰Po concentration in the omnivorous species is about 2.9 times higher than in the carnivorous species. The species living in demersal zone accumulated a high ²¹⁰Po in comparison with species living in reef-associated and pelagic-neritic zones. The calculated annual committed effective dose from ²¹⁰Po due to the ingestion of seafood from demersal zone and bivalve species of the area was significant high.

A review of radioactivity in the Gulf region

The region around the Gulf is moving toward a nuclear energy option with the first nuclear power plant now operational in Bushehr, Iran. Others are soon to be commissioned in Abu Dhabi and in Saudi Arabia. For this reason, radiological safety is becoming a prime concern in the region. This review compiles published data on radionuclide concentrations in seawater, sediment, and biota that have been analyzed in the Gulf countries, along with spatial distribution patterns to enable a synoptic view of the available datasets. The seawater concentrations of ³H, ²¹⁰Po, ²¹⁰Pb, ¹³⁷Cs, and ⁹⁰Sr varied between 130 and 146, 0.48-0.68, 0.75-0.89, 1.25-1.38, 0.57-0.78 mBq L^-1, respectively. The ²²⁶Ra concentration in seawater varied between 0.26 and 3.82 Bq L^-1. Extremely high ⁴⁰K concentrations between 132 and 149 Bq L^-1 have been reported from the Iranian coast compared to 8.9-9.3 Bq L^-1 from the western side of the Gulf. Concentrations of ⁴⁰K, total ²¹⁰Pb, ¹³⁷Cs, ⁹⁰Sr, ²²⁶Ra, ²²⁸Ra, ²³⁸U, ²³⁵U, ²³⁴U, ^239+240Pu, and ²³⁸Pu were determined in sediment and ranged between 353 and 445, 23.6-44.3, 1.0-3.1, 4.8-5.29, 17.3-20.5, 15-16.4, 28.7-31.4, 1.26-1.30, 29.7-30.0, 0.045-0.21 and 0.028-0.03 Bq kg^-1 dry weight, respectively. Significantly higher ¹³⁷Cs values have been reported from the Iranian coast compared to the western coast of the Gulf. Whole fish concentrations of ⁴⁰K, ²²⁶Ra, ²²⁴Ra, ²²⁸Ra, ¹³⁷Cs, ²¹⁰Po and ⁹⁰Sr ranged between 230 and 447, 0.7-7.3, <0.5-6.6, <0.5-15.80, <0.17, 0.88-4.26 and 1.86-5.34 Bq kg^-1 dry weight, respectively. ²¹⁰Po was found to be highly concentrated in several marine organisms with the highest ²¹⁰Po concentration found in the clam Marcia marmorata (193.5-215.6 Bq kg^-1 dry weight). The review highlights the overall paucity of data and inconsistencies in the measurement of radionuclides throughout the Gulf region. Further, since the region is moving toward nuclear energy to meet its increasing energy demand, and coupled with the environmental effects from offshore oil exploration and the heavy impact of climate change, there is a pressing need to undertake a comprehensive marine radioactivity monitoring and assessment effort by conducting a joint cruise in the Gulf with participation of all the adjoining countries. Several recommendations on sampling marine matrixes in the Gulf are given with the aim of improving comparability of radionuclide data from the various studies undertaken in the Gulf region.

Assessment of the annual committed effective dose due to the 210Po ingestion from selected sea-food species in Vietnam

Activity concentration of ²¹⁰Po in the edible muscle tissues of twelve sea-food species (the most common marine food consumed of population in Vietnam) were analyzed using the PIPS detectors ORTEC Alpha-Ensemble spectrometer. The ²¹⁰Po activity concentration in studied samples was found to vary from 0.82 ± 0.47 to 70.3 ± 8.5 Bq/kg fresh weight. The highest activity concentration was recorded for the Blood cockle (Anadara granosa) and the lowest for Silver pomfret (Pampus argenteus). The annual committed effective dose (CED) of ²¹⁰Po to humans (the local residents) due to ingestion of each studied species was calculated from 18.5 to 1586 μSv/y. The average annual committed effective dose value was reported 394 μSv/y, which is marginally higher than the average CED contributed from ingestion of food and water total in global background (290 μSv/y).

Assessment of loss of 210Po from fish and shrimp by cooking and its effect on dose estimates to humans ingesting seafood

An experimental study was conducted to assess loss of ²¹⁰Po due to cooking fresh seafood, and provide a more realistic and reliable dose estimate that humans may receive from consuming cooked seafood. Fresh fish and shrimp samples from Northern Gulf waters were grilled and boiled to simulate the effect of different cooking methods. Sixteen different species of fish were compared and significant differences in ²¹⁰Po concentration in uncooked samples were observed between species (ANOVA I, F_15,79 = 362.81, p < 0.0001). The effect of the treatment (uncooked, grilled, boiled and stock) was compared for each species and it was found that cooking led to a significant decrease in ²¹⁰Po concentration ranging from 14 to 58% compared to the uncooked samples, with no difference between grilled or boiled treatments. The effect of the cooking and shrimp treatment on ²¹⁰Po concentration was tested using ANOVA II after logarithmic transformation. Cooking led to a significant 38% reduction of ²¹⁰Po concentration as compared to uncooked treatments with no difference between grilled and boiled samples (ANOVA I: F_3,99 = 14.72, p < 0.0001). The two treatments with deveined shrimp led to a 75% decrease in ²¹⁰Po concentration as compared to all other treatments. As a consequence, cooked deveined shrimp contained an 84% lower ²¹⁰Po concentration than whole uncooked shrimp. As ²¹⁰Po is known to be the major contributor to radiation dose in humans consuming seafood, based on the results obtained, it is evident there is a need to re-examine how committed effective doses (CEDs) are best calculated for seafood consuming populations considering that most populations consume fish and shellfish cooked.

Assessment of the committed effective dose due to the 210Po intake from fish consumption for the Arabian Gulf population

This study aims to assess the committed effective dose due to the intake of ²¹⁰Po from the consumption of fish in Arabian Gulf countries. Twenty different kinds of fish, which represent the most common fish species consumed in the Arabian Gulf countries, were analyzed using alpha spectrometer technique. ²¹⁰Po activity concentrations in fish samples were found to vary over a wide range from 0.1 to 14.7 Bq kg^-1 fresh weight. This variation of ²¹⁰Po concentrations between various type of fish samples might be attributed to the feeding type pattern and the size of fish. The annual committed effective dose due to ingestion of ²¹⁰Po in fish species for adults in the Arabian Gulf countries was estimated and found to vary from 38 μSv in Bahrain to 85 μSv in Oman with an average value of 59 μSv. These values are considered relatively high compared to those reported in some other regions. However, it is still much lower than the world average ingestion dose due to natural radiation sources.

210Po bioaccumulation and trophic transfer in marine food chains in the northern Arabian Gulf

The tendency of ²¹⁰Po to concentrate in body tissue poses a serious concern of radiological safety. This study compiles available information and presents recent ²¹⁰Po data for the marine food web in the northern Gulf waters. Since ²¹⁰Po is concentrated in marine biota, a large number of samples of various marine organisms covering several trophic levels, from microalgae to sharks, were analyzed. ²¹⁰Po was found to be highly concentrated in several marine species with the highest ²¹⁰Po concentrations found in yellowfin tuna, i.e. 37.3-44.9, 451-548, and 1511-1693 Bq kg^-1 wwt in muscle, digestive system and liver, respectively. In most dissected fish samples, ²¹⁰Po showed increasing concentrations in the following order: edible tissue, gills, digestive system, liver and fecal matter. Fish feces had ²¹⁰Po concentrations several orders of magnitude higher than that in seawater, fish muscle, and the fishes' ingested food. The high ²¹⁰Po concentration in fish fecal matter suggests that the bulk of ²¹⁰Po content in fish is eventually excreted back into the environment as fecal pellets. In most fish high concentrations were noted in liver, with the highest ²¹⁰Po concentration recorded in yellowfin tuna liver. Moreover, ²¹⁰Po concentration in the soft tissue of tunicate and bryozoan samples were 872-1012 and 402-527 Bq kg^-1 wwt, respectively, far higher than that in fish muscle (0.04-44.9 Bq kg^-1 wwt). It was observed that the maximum ²¹⁰Po concentration in edible fish tissue among the fish in trophic level 2 was an order of magnitude lower than those in trophic level 3 and two orders of magnitude lower compared to fish in trophic level 4. The highest concentrations in the muscle tissue were observed in the following order: tunicate > bryozoan > mollusc > crustacean > algae > fish. Among all the biota analyzed, the highest overall concentration of ²¹⁰Po was noted in yellowfin tuna (Thunnus albacores) indicating a potential biomagnification of ²¹⁰Po in this particular top predator species. In general, ²¹⁰Po concentrations found in the commercially important fish from Kuwaiti waters were comparable to levels that have been reported for similar fish species from several other marine areas worldwide.

Radioactivity in the Kuwait marine environment--Baseline measurements and review

The Arabian Gulf region is moving towards a nuclear energy option with the first nuclear power plant now operational in Bushehr, Iran, and others soon to be constructed in Abu Dhabi and Saudi Arabia. Radiological safety is becoming a prime concern in the region. This study compiles available data and presents recent radionuclide data for the northern Gulf waters, considered as pre-nuclear which will be a valuable dataset for future monitoring work in this region. Radionuclide monitoring in the marine environment is a matter of prime concern for Kuwait, and an assessment of the potential impact of radionuclides requires the establishment and regular updating of baseline levels of artificial and natural radionuclides in various environmental compartments. Here we present baseline measurements for (210)Po, (210)Pb, (137)Cs, (90)Sr, and (3)H in Kuwait waters. The seawater concentration of (3)H, (210)Po, (210)Pb, (137)Cs, and (90)Sr vary between 130-146, 0.48-0.68, 0.75-0.89, 1.25-1.38 and 0.57-0.78 mBq L(-1), respectively. The (40)K concentration in seawater varies between 8.9-9.3 Bq L(-1). The concentration of (40)K, total (210)Pb, (137)Cs, (90)Sr, (226)Ra, (228)Ra, (238)U, (235)U, (234)U, (239+240)Pu and (238)Pu were determined in sediments and range, respectively, between 353-445, 23.6-44.3, 1.0-3.1, 4.8-5.29, 17.3-20.5, 15-16.4, 28.7-31.4, 1.26-1.30, 29.7-30.0, 0.045-0.21 and 0.028-0.03 Bq kg(-1) dry weight. Since, radionuclides are concentrated in marine biota, a large number of marine biota samples covering several trophic levels, from microalgae to sharks, were analyzed. The whole fish concentration of (40)K, (226)Ra, (224)Ra, (228)Ra, (137)Cs, (210)Po and (90)Sr range between 230-447, 0.7-7.3, <0.5-6.6, <0.5-15.80, <0.17, 0.88-4.26 and 1.86-5.34 Bq kg(-1) dry weight, respectively. (210)Po was found to be highly concentrated in several marine organisms with the highest (210)Po concentration found in Marica marmorata (193.5-215.6 Bq kg(-1) dry weight). (210)Po in most dissected fish samples shows increasing concentrations in the following order: edible tissue, gills, digestive system, liver and fecal matter. Fish fecal pellets had (210)Po concentrations several orders of magnitude higher than the seawater, fish muscle, and the fishes' ingested food. The high (210)Po concentration in fish fecal matter, suggest that the bulk of (210)Po content in fish was eventually excreted back into the environment as fecal pellets. In most fish high concentrations were noted in liver, with the highest (210)Po concentration recorded in shark liver (126.2-141.5 Bq kg(-1) wet). Moreover, (210)Po concentration in the soft tissue of molluscs (10.36-215.60 Bq kg(-1) dry weight) was far higher than that in fish muscle (0.05-7.49 Bq kg(-1) wet weight). A seasonal drop in (210)Po concentration in seawater was observed to vary with the abundance of phytoplankton and macroalgae due possibly to biological dilution. (137)Cs concentration in all the fish sampled was below the detection limit, and the concentration in seawater was also low; hence such low levels provide an opportunity to use this radionuclide as an indicator for any future radiocesium releases in this region.