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PubMedDate not supplied

The assessment of radiocaesium intake from food using duplicate diet and whole-body monitoring techniques.

A duplicate diet study has been carried out on a group of Harwell employees in order to investigate the food types in which radiocaesium from Chernobyl was most likely to be found, and also the intake of radiocaesium in food with relation to observed whole-body levels. The duplicate diet study indicated that the highest levels of radiocaesium were in milk and meat or fruit and vegetables. Radiocaesium concentrations in food of all types are small compared to the most restrictive generalized derived limit. Daily intakes of radiocaesium measured by the diet study, of the order of 2-3 Bq day-1, generally agreed with values calculated from whole-body measurements. Committed does from radiocaesium have been estimated from dietary intakes to be in the range 3-29 muSv year-1, while whole-body measurements indicate a range of 6-18 muSv year-1; these doses are small compared to other sources of internal irradiation and to recommended limits.

Accidents↗
PubMedDate not supplied

An investigation of the availability of 137Cs and 239 + 240Pu for gut absorption in winkles following cooking and in vitro simulated gastro-intestinal digestion.

The consumption of plutonium, americium and radiocaesium in locally collected shellfish is an important contributor to the radiation dose received by seafood consumers living in West Cumbria. Only a small fraction of the actinide activity is assumed to be absorbed via the gut whilst it is assumed that all the radiocaesium is. Solubilization studies reported here using an in vitro digestion method support the former assumption but not the latter, suggesting that the proportion of the 137Cs available for absorption could be significantly smaller than unity where a large percentage of the ingested Cs is adsorbed onto inorganic sedimentary material. Such a situation arises near the Sellafield nuclear-reprocessing plant where a high proportion of the radiocaesium (and plutonium) in the winkles collected locally and subsequently cooked is associated with inorganic particulate matter.

Biological Availability↗
PubMed1999

Radionuclides and trace elements in fish collected upstream and downstream of Los Alamos National Laboratory and the doses to humans from the consumption of muscle and bone.

The purpose of this study was to determine radionuclide and trace element concentrations in bottom-feeding fish (catfish, carp, and suckers) collected from the confluences of some of the major canyons that cross Los Alamos National Laboratory (LANL) lands with the Rio Grande (RG) and the potential radiological doses from the ingestion of these fish. Samples of muscle and bone (and viscera in some cases) were analyzed for 3H, 90Sr, 137Cs, totU, 238Pu, 239,240Pu, and 241Am and Ag, As, Ba, Be, Cr, Cd, Cu, Hg, Ni, Pb, Sb, Se, and Tl. Most radionuclides, with the exception of 90Sr, in the muscle plus bone portions of fish collected from LANL canyons/RG were not significantly (p < 0.05) higher from fish collected upstream (San Ildefonso/background) of LANL. Strontium-90 in fish muscle plus bone tissue significantly (p < 0.05) increases in concentration starting from Los Alamos Canyon, the most upstream confluence (fish contained 3.4E-02 pCi g-1 [126E-02 Bq kg-1]), to Frijoles Canyon, the most downstream confluence (fish contained 14E-02 pCi g-1 [518E-02 Bq kg-1]). The differences in 90Sr concentrations in fish collected downstream and upstream (background) of LANL, however, were very small. Based on the average concentrations (+/- 2SD) of radionuclides in fish tissue from the four LANL confluences, the committed effective dose equivalent from the ingestion of 46 lb (21 kg) (maximum ingestion rate per person per year) of fish muscle plus bone, after the subtraction of background, was 0.1 +/- 0.1 mrem y-1 (1.0 +/- 1.0 microSv y-1), and was far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem y-1 (1000 microSv y-1). Of the trace elements that were found above the limits of detection (Ba, Cu, and Hg) in fish muscle collected from the confluences of canyons that cross LANL and the RG, none were in significantly higher (p < 0.05) concentrations than in muscle of fish collected from background locations.

Animals↗
PubMed1999

Radionuclides in deer and elk from Los Alamos National Laboratory and the doses to humans from the ingestion of muscle and bone.

This paper summarizes radionuclide concentrations (3H, 90Sr, 137Cs, 238Pu, 239,240Pu, 241Am, and totU) in muscle and bone tissue of mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) collected from Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer (n = 11) and elk (n = 22) collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p < 0.10) than in similar tissues from deer (n = 3) and elk (n = 7) collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% of LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDEs (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (50 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.22 mrem y-1 (2.2 microSv y-1), deer bone = 3.8 mrem y-1 (38 microSv y-1), elk muscle = 0.12 mrem y-1 (1.2 microSv y-1), and elk bone = 1.7 mrem y-1 (17 microSv y-1). All CEDEs were far below the International Commission on Radiological Protection guideline of 100 mrem y-1 (1000 microSv y-1), and the highest muscle plus bone net CEDE corresponded to a RECF of 2E-06, which is far below the Environmental Protection Agency upper level guideline of 1E-04.

Animals↗
PubMed2002

The placental transfer of cerium: experimental studies and estimates of doses to the human fetus from 141Ce and 144Ce.

PURPOSE: To measure the transfer of cerium from mother to fetus in experimental animals and estimate doses to the human fetus following intakes of radioisotopes of Ce. MATERIALS AND METHODS: Cerium-141 in chloride solution was administered intravenously to rats at different stages of pregnancy (days 9.5, 12.5 or 18.5), and retention in the embryo/fetus and associated tissues was measured 3 days later in each case. Retention in rat fetal tissues on day 21.5 (shortly before birth) was also measured after administration of 141Ce chloride 1 month prior to conception or 141Ce citrate on day 18.5. Cerium-141 chloride was administered to guinea pigs on day 50 for measurements of fetal retention on day 57 (shortly before birth). RESULTS: Retention of 141Ce in the rat embryo/fetus, measured at 3 days after administration to the mother, increased from about 0.00002% of injected activity per embryo/fetus on day 12.5 to about 0.014% on day 21.5 of gestation. However, the relative concentrations of 141Ce in the embryo/fetus and mother (CF:CM ratio) were between 0.005 and 0.01 in each case. After 141Ce administration prior to conception, retention by the rat fetus on day 21.5 was substantially lower than after short-term administration. Comparison of retention of 141Ce on day 21.5 after administration on day 18.5 as either chloride or citrate showed similar levels in maternal tissues but greater transfer to the fetus (CF:CM ratio of 0.03). Retention in the guinea pig fetus in late gestation at 7 days after administration of (141)Ce chloride was about 0.05% injected activity per fetus, corresponding to a CF:CM ratio of about 0.02. CONCLUSION: These results and other published animal data have been used to specify CF:CM ratios for use in the calculation of doses to the human fetus. The values used were 0.05 for intakes during pregnancy and 0.01 for intakes prior to conception. Doses to the offspring after maternal ingestion of 141Ce or 144Ce are largely due to irradiation from activity in the maternal colon and are insensitive to CF:CM. After inhalation, however, absorption of Ce to blood is much greater and doses to the offspring are dominated by the contribution from activity in the fetus, and therefore dependent on the CF:CM ratio used.

Animals↗
PubMed1984

The uptake and turnover of 90Sr in the human skeleton.

In the United Kingdom, measurements have been made of the concentration of 90Sr in human bone from 1955 to 1970, and in human diet since 1958. A correlation of these two series of observations has enabled estimates to be made of (i) the fraction of the dietary intake of 90Sr that reaches the skeleton, (ii) the rate of turnover of 90Sr in the skeleton, and (iii) the way in which both these parameters vary with age. The results may be used to predict future levels of 90Sr in human bone from measurements of the radionuclide in diet, and also to calculate the radiation doses received by tissues in bone from intakes of 90Sr and 89Sr.

Adolescent↗
PubMed1998

Dose due to man-made radionuclides in terrestrial wild foods near Sellafield.

Radiological dose implications for consumers of wild foods around Sellafield have been assessed. Habits were surveyed from 72 households, mostly within a few kilometres of Sellafield. A few people were included who lived further away but collect wild foods close to Sellafield. Dose estimates were based on measured gamma emitters, as well as 239Pu, 241Am, 14C and 129I in selected samples. In all cases, doses were dominated by 137Cs. One infant was identified who consumed wild food, giving an estimated effective dose of 0.3 microSv a(-1). In the age group 2 to 10 years a mean dose of 0.51 microSv a(-1), and a maximum of 2.8 microSv a(-1), were estimated. Intakes by adults were higher and resulted in more radiologically significant doses. The extreme individual received a dose of 32 microSv a(-1) largely due to consumption of honey that included contributions from the Chernobyl accident, and hedgerow fruits. This is comparable to doses to the critical group for consumption of conventional agricultural produce close to the Sellafield site. The 97.5th percentile dose, for all age groups of consumers taken together, was 16.6 microSv a(-1), or 6.2 microSv a(-1) if the contributions from Chernobyl are excluded. Considering the contributions from different foods to the whole group of 181 wild food consumers, the rank order is honey, blackberries and venison.

Adult↗
PubMed1998

Transfer across the human gut of environmental plutonium, americium, cobalt, caesium and technetium: studies with cockles (Cerastoderma edule) from the Irish Sea.

Our previous studies have indicated lower values of the gut transfer factor ('f1 values') for plutonium and americium in winkles (Littorina littorea) than adopted by ICRP. The present study was undertaken primarily to investigate whether this observation extends to other species. Samples of cockles (Carastoderma edule) from Ravenglass, Cumbria were eaten by volunteers who provided 24 h samples of urine and faeces. Urine samples indicated f1 values for cockles which were higher than for winkles; for plutonium these ranged overall up to 7 x 10(-4) with an arithmetic mean in the range (2-3) x 10(-4), and for americium up to 2.6 x 10(-4) with an arithmetic mean of 1.2 x 10(-4). Limited data based on volunteers eating cockles from the Solway suggest that f1 values for americium may be greater at distance from Sellafield. The measured values compare with 5 x 10(-4) used by the ICRP for environmental forms of both elements, which would appear to provide adequate protection when calculating doses from Cumbrian cockles. Data for other nuclides were obtained by analysing faecal samples from the volunteers who ate the Ravenglass cockles. Cobalt-60 showed an f1 value in the region of 0.2, twice the value currently used by ICRP. For 137Cs, variabilities were indicated in the range 0.08 to 0.43, within the ICRP value of f1 = 1.0. Technetium-99 gave f1 values up to about 0.6, in reasonable conformity with the ICRP value of 0.5.

Americium↗
PubMed2000

Dose reduction associated with various countermeasures in freshwater fish contamination in Hong Kong.

Based on a model developed specifically for the local freshwater fish culture system, a dose transfer coefficient for 137Cs of 1.15 mSv per MBq m(-2) is obtained for the consumption of freshwater fish in the first year after deposition. Several countermeasures are suggested to reduce the ingestion dose resulting from a nuclear accident. These countermeasures include suspension of fish culture for a period of time after deposition of radionuclides, the removal of the contaminated pond water and, in the more severe cases, the removal of the sediment. The dose reductions that could be achieved by these countermeasures and the effects of their implementation times relative to the input are investigated. The time of resumption of fish culture in affected ponds and the resulting ingestion dose have also been studied in detail. It is found that reusing a pond for fresh fish culture after 6 months would reduce the ingestion dose in the following year by half as compared with that if the pond was reused a short period of time after deposition. An empirical formula linking the peak concentration in fish and the ingestion dose has been derived. The results are useful to decision-makers in limiting the ingestion dose arising from consumption of contaminated freshwater fish after nuclear accidents.

Animals↗
PubMed2001

Transfer across the human gut of environmental technetium in lobsters (Homarus gammarus L.) from the Irish Sea.

Few data are available on the uptake by the human gut of the element technetium. Of current radiological interest in connection with discharges of technetium-99 in liquid discharges from BNFL, Sellafield, is uptake from European lobsters (Homarus gammarus), whose edible parts are known to concentrate technetium. In this study, a group of eight adult volunteers (six males and two females) ate samples of edible flesh from lobsters caught off the west Cumbrian coast and provided 24 h samples of urine and faeces for analysis. Detection of uptake from the gut by difference between intake and faecal measurements proved insensitive, suggesting a low value of the gut transfer factor (f1 value) of up to 0.1 with a maximum (two standard deviations) level of about 0.3. In urine, technetium was detectable at a relatively low level compared with the intakes, consistent with a low absorption across the gut. Values for f1 were derived with the aid of literature data for excretion following intravenous administration of technetium-95 m as pertechnetate, and gave averaged data for f1 in the range 0.046 to 0.23. These results are in broad conformity with those derived from the faecal measurements, and suggest a lower value than the 0.5 used by ICRP.

Adult↗
PubMed2003

Predicting the 137Cs ingestion dose from marine fish consumption in Hong Kong after an accidental release.

Caesium-137 is one of the more important radionuclides released during a nuclear power plant accident. Based on a mathematical model developed earlier by the present authors for estimating 137Cs ingestion dose from consumption of marine fish in Hong Kong, doses due to an accidental release into Daya Bay from the Guangdong Nuclear Power Station are predicted. Assuming a release of 30000 TBq of 137Cs, results show that the cumulative dose rises rapidly during the first five years and then gradually levels off. In the first and 50th years after discharge, doses to an average Hong Kong citizen would cumulate to 17 and 38 microSv respectively, which are dominated by the contribution from fish cultured in Hong Kong waters. The first year dose to members of the critical group of local fish farmers is estimated to be 1600 microSv, accumulating to 3600 microSv in the 50th year. Apart from this small number of critical group members whose doses may need some monitoring, the doses to the population at large are considered small compared with an annual dose of 175 microSv from ingestion of natural radionuclides in food and drinks in Hong Kong.

Animals↗