131I In Milk Research Articles

Radionuclide transfer from feed to camel milk

The transfer of 137Cs, 85Sr, 131I, 210Po, 210Pb and 238U from feed to camel's milk was investigated in a pilot experiment with three lactating camels. For a period of 60 days, the animals were fed on spiked feed containing the studied radionuclides. They were subsequently returned to a contamination-free diet and monitored for another 90 days. The activity concentrations of 137Cs, 85Sr and 131I in milk decreased with time and reached background levels after 20 days. Equilibrium transfer coefficients and biological half-lives were estimated and transfer coefficients were calculated as (8.1 ± 3.6) × 10−4, (4.4 ± 1.6) × 10−2, (7.8 ± 3.9) × 10−4, (2.7 ± 3.5) × 10−4, (1.8 ± 1.5) × 10−4 and (7.0 ± 3.6) × 10−3 d L−1 for 85Sr, 131I, 137Cs, 210Po, 210Pb and 238U, respectively. The biological half-lives were estimated to be 6.4, 4.2, 8.9, and 53.3 days for 85Sr, 131I, 137Cs, and 238U, respectively. Estimates of the half-lives were based on a one component model: it was found that the half-life values measured for artificial radionuclides were slightly shorter than those for natural radionuclides. The data obtained in the study are the first published experimental data on radionuclide transfer to camel milk.

Ecological half-life of I-131 in milk after dry and wet radionuclide deposition due to the Chernobyl accident

Numerous measurements of 131 I concentration in milk following the Chernobyl accident have shown a wide range of clarification half-life values. By results of spectrometric measurements of the milk, performed in 1986 in Tula region (Russia), a connection between a 131 I decreasing half-life in milk and a level of radioactive contamination in a locality and a level of precipitation during passage of a radioactive cloud is analysed. Values of the 131 I half-life in milk increase from 3.0 d at the smallest area contamination by 137 Cs to 5.5–6.0 d at the contamination above the 200 kBq/m2 . The half-life of 131 I removal from milk depends on the precipitation level at the time of radioactive fallouts in places of milk sampling. Tef increases from 2.8–3.5 d (dry deposition) to the value 5.5–6.0 with precipitation increasing up to 6–9 mm. The half-life value does not change with further precipitation increase. This finding should be taken into account in thyroid dose estimations for inhabitants of contaminated areas.

Problem on estimation of the content of 131I in milk in the “iodine” period of the Chernobyl accident

Measurements of the beta-activity of milk, serving as the main source of information on the radioactive contamination of the environment by the iodine isotope 131I, carried out on a DP-100 radiometer in the early post-Chernobyl period (1986) in Belarus, have been mathematically simulated. The results obtained allow the conclusion that the indicated measurements should be analyzed again with consideration for all of the nuclides present in milk.

Gamma and beta background counting of I-131 in milk in the vicinity of the Nuclear Center, Mexico

The aim of this work was to determine the contamination of I-131 in milk samples by low background γ-spectrometry and low background β-counting techniques in the vicinity of the Nuclear Center in Salazar, Mexico. The low background γ-spectrometry was done directly. The determination by low background β-counting consisted of a radiochemical separation of I-131 by ion exchange from the milk samples followed by measurement in a low background β-counting system. The results indicated that there was no contamination of I-131 in the samples.

Use of large gamma-ray detector to measure 131I in milk and water at low levels.

A lower limit of detection of 0.04 Bq L-1 for measuring 131I in milk or water with a gamma-ray spectrometer was achieved with a large 118% intrinsic germanium detector. Three-liter samples with 131I tracer in a reentrant beaker were counted within a lead shield for 12,000 to 55,000 s to demonstrate detection at this concentration. Samples of milk collected at dairies and counted for 28,000 s showed no 131I at this level (as expected), but 137Cs from fallout was detected in some samples near its detection limit of 0.03 Bq L-1.

Contaminant Transport through Agroecosystems: Assessing Relative Importance of Environmental, Physiological, and Management Factors.

Agroecosystems can become contaminated by atmospherically released radionuclides. The subsequent concentrations of radionuclides in foods are dependent on numerous environmental, physiological, and management factors. We compared four approaches for estimating the relative importance of several of these factors in determining concentrations of 131 I and 137 Cs in milk. A series of sensitivity analyses with Monte Carlo and full-factorial sampling designs was conducted on the PATHWAY model, which simulates radionuclide transport through an agroecosystem. Sensitivity of time-integrated concentrations in milk was estimated as a function of the time of year that fallout was deposited and as a function of time following a spring deposition. The dominant parameters affecting time-integrated concentrations of 131 I in milk were the initial fraction of radionuclides deposited on vegetation, timing and amount of pasture consumption, and the production rate of milk. For time-integrated concentrations of the longer-lived 137 Cs in milk, resuspension was a dominant parameter and pasture use was less important. The sampling designs were compared by ranking the parameters to which the model output is sensitive. The three sampling designs based on parameter variances produced sets of ranks that were similar to each other but differed from the ranking produced by the sampling design based on parameter magnitude. The results indicate which data are most crucial for real-time calculations following an accident and how subsequent dose from ingestion can be most effectively reduced, provide insight into model behavior, and help prioritize future research. This paper demonstrates the importance of variance-based sensitivity analysis.

Investigation on the measurement of radioactivities of 131I in milk.

The analytical method combined with chemical treatment (ion exchange, solvent extraction, coprecipitation) and measurement of β radiation by a low back ground counter has been adopted in "Standard Method of Analysis for Hygienic Chemists" as the analytical method of 131I in milk. However, it was difficult to apply this method to the analysis of some kinds of milk on the market, because some colloidal phenomena appeared at the coprecipitation step. As a result of detection by use of thin layer chromatography and mass spectrometry, it is guessed that this is caused by materials possessing surface active action, such as fatty acids which constitute milk fat (e.g., palmitic acid, stearic acid etc.), and surface active agents added to dairy products. Therefore, after the removal with ether of these surfactants before the coprecipitation step, the measurement of radioactivities of 131I can be carried out without trouble.

Radiocesium concentration in migratory birds wintering in Spain after the Chernobyl accident.

Levels of 137Cs and 134Cs resulting from the Chernobyl nuclear accident were studied in 195 birds that winter in two regions of Spain. Only five of the 12 species examined were contaminated. The average values for 137Cs vary between 1.6 and 41 Bq kg-1 fresh. In particular, the contamination for song-thrushes (Turdus philomelos) are compared between the regions of Extremadura and Valencia, 350 km east of Extremadura at the same latitude. The results show that the contamination of birds wintering in Spain decreases from east to west. The whole-body dose commitment for humans consuming these contaminated birds was calculated. The values are well below the established ICRP guideline.

Feeding green-cut forage contaminated by radioactive fallout to dairy cows.

Grass contaminated by radioactive fallout from the Chernobyl accident was cut with 150 mm (Treatment 1) and 50 mm (Treatment 2) stubble height and fed to 20 dairy cows. The transfer of 137Cs and 131I from the greencut forage to milk was studied during a four-week and a two-week period, respectively. The four-week period was followed by a three-week period with nearly uncontaminated feeds. Cutting with high stubble height significantly reduced the activity concentration in forage compared with low stubble cutting, the average contents kg-1 dry matter being 385 Bq 137Cs and 24 Bq 131I in Treatment 1 versus 6656 Bq 137Cs and 249 Bq 131I in Treatment 2. Apparent treatment effects were also demonstrated by the 137Cs concentration in milk, with maximum weekly means of 23 Bq kg-1 (Treatment 1) and 92 Bq kg-1 (Treatment 2). Single day maximum concentrations of 131I in milk were 4 Bq kg-1 (Treatment 1) and 9 Bq kg-1 (Treatment 2). The mean transfer coefficients (d kg-1) were calculated to be 0.67 X 10(-2) and 0.19 X 10(-2) for 137Cs (weeks 2-4) and 1.8 X 10(-2) and 0.2 X 10(-2) for 131I (week 2) in Treatments 1 and 2, respectively. The lower value for 137Cs might possibly be associated with an enhanced ash content of the forage. Feeding nearly uncontaminated rations rapidly decreased the 137Cs levels in milk in both treatments with calculated effective half-times over the three-week period of 10 and 7 d, respectively.

Monitoring of 131I in milk and rain water in Japan following the reactor accident at Chernobyl and estimates of human thyroidal dose equivalents.

Iodine-131 in milk and in rain water in Nagoya, Japan, (a location 8,000 km from Chernobyl) was monitored between May and July 1986. The 131I concentration in rain water ranged from 43.1 Bq L-1 on 4 May to 15 mBq L-1 on 12 July, and that in milk ranged from 21.8 Bq L-1 on 19 May to 11 mBq L-1 on 14 July. Iodine-131 concentrations in milk were estimated to be 4 to 6 times greater than those in rain water during the first few weeks after the accident. Both concentrations decreased with approximately the same effective half-life of 5.9 +/- 0.3 d for rain water and 5.0 +/- 0.2 d for milk. The 131I concentration in milk sold in markets varied from dairy to dairy and ranged from 0.07 to 0.2 times that in fresh milk. The maximum thyroidal dose equivalents estimated for an adult man and for a baby were far lower than the population annual dose equivalent to the thyroid from natural radiation.

Environmental radioactivity around tokai-works after the reactor accident at chernobyl

Following the reactor accident at Chernobyl, environmental samples of air, rain water and agricultural and marine products were collected and analyzed by gamma- and alpha-spectrometry. The highest concentrations of 131I in the environmental samples were as follows: 1·0× −1 Bqm −3 (aerosol-associated in air); 3·0×10 −1 Bqm −3 (gaseous in air); 2·1×10 2 bq kg −1 (plants); 1·4×10 1 Bq litre −1 (milk). Other nuclides such as 95Zr, 95Nb, 103Ru, 106Ru, 125Sb, 129mTe, 132I/ 132Te, 134Cs, 137Cs, 140Ba/ 140La, 141Ce and 144Ce were also observed in various environmental samples. 110mAg was only detected in marine products such as cephalopoda and shellfish, 239,240Pu and 241Am originating from the accident were not identified. Based on the monitoring results at one dairy farm, we have derived an equation to model the transport of 131I from pasture grass to milk. This equation was then applied to the data from two other farms around Tokai-Works and the calculated 131I activities in milk were compared with those measured. The equation shows good predictive capabilities for quantification of the peak concentrations of 131I in milk but underestimates longer-term activities.

A preliminary assessment of the consequences for inhabitants of the UK of the Chernobyl accident.

The accident with the nuclear power reactor at Chernobyl in the USSR resulted in the release of substantial quantities of radioactive material and subsequent increases in radioactivity in the environment in many countries. In this paper the situation in the UK is considered and, from the preliminary monitoring measurements, the major routes of exposure of the population are identified and quantified. For the most part exposures in the UK are within variations in levels of natural background radiation to be found in Europe. An exception is the dose likely to have been received by the thyroids of young people in the north of the UK. From reported measurements of I-131 in milk it is predicted that thyroid doses up to 10-20 times the annual doses received from 'normal' natural background radiation might have affected young children drinking fresh cows' milk. The ways in which this component of exposure could have been reduced and the criteria that govern decisions as to whether or not to implement counter-measures are discussed. The importance of I-131 in milk as a route of exposure of the population to radioactivity is a feature that the Chernobyl accident has in common with the Windscale accident in the UK in 1957, and underlines the importance of milk-producing regions in relation to reactor-sitting policy.

Determination of 125I, 129I and 131I in milk

Abstract The determination of iodine radioisotopes in cow's milk has been reconsidered and improved in order to reach higher accuracy and sensitivity and a shorter analysis time.

Validation of pathway, a simulation model of the transport of radionuclides through agroecosystems

PATHWAY is a dynamic simulation model of the transport of radionuclides from fallout through the agricultural foodchain. The model was developed to fulfill the need for a realistic, testable, completely time dependent model to estimate radionuclide ingestion by humans exposed to fallout patterns originating at the Nevada Test Site during the 1950's. The model simulates the fate of radionuclides in various management units (pastures, gardens, croplands, etc.) of an agro-ecosystem. The agricultural products currently considered in the model are pasture grass, alfalfa, grains, garden vegetables, milk, eggs, beef, and poultry. Harvested and stored products, such as hay and canned vegetables, are also represented in the model. Animal diets are specified on a daily basis. Thus, the model can be used to simulate the fate of radionuclides from both acute and chronic fallout deposition. The utility and credibility of radionuclide transport simulation models are severely limited without rigorous testing of their predictive capabilities against real observations. This paper reviews exercises testing the overall accuracy and temporal dynamics simulated by the PATHWAY model against 37 sets of observed data. These data include concentrations of 137Cs, 90Sr, 140Ba, and 131I in milk, beef, alfalfa, and pasture grass from several western states following deposition of the radionuclides in fallout. In addition, the model is tested against observations of concentrations of 131I in milk following the accident at the Windscale reactor in England. The statistical tests used to compare the predictions of PATHWAY to the observations include a correlation analysis, a paired t-test, and a binomial test. We use the correlation coefficient between observations and predictions through time to compare the dynamics of the simulated and real world system. Plots of the residuals from regression are then examined for bias between the predictions and observations. The significance of any trends in the residuals is evaluated using a runs test. The paired t-test and the binomial test are used to evaluate the accuracy of PATHWAY's predictions. The hypothesis for the paired t-test is that the ratio of predictions to observations is 1. The paired t-test can be used to test hypotheses about ratios because the distributions of observations and predictions appear to be lognormal. However, the paired t-test does not consider uncertainty in the predictions of the model. We use a binomial test to compare the observed data to an interval estimate from PATHWAY. The interval corresponds to a 95% confidence interval on the prediction, and is derived from uncertainty analyses that have been conducted on PATHWAY. PATHWAY's predictions are significantly correlated with observed levels of 137Cs and 90Sr in pasture and alfalfa. PATHWAY also simulates the dynamics of 131I, 140Ba, and 137Cs in milk well, but fails to predict what appears to be a long term accumulation of 90Sr in the agro-ecosystem. PATHWAY predicts the absolute concentrations of 131I in milk quite well, but tends to predict levels of 140Ba, 90Sr, 137Cs in milk that are different from those observed by factors of 2 to 7. PATHWAY predicts levels of 137Cs and 90Sr in pasture and beef within a factor of 2 of those observed.

ＮａＩ（Ｔｌ）スペクトロメトリーによる牛乳中放射性ヨウ素定量法の誤差評価

An uncertainty in the method of determination of radioactive iodine (131I) in milk with a NaI (Tl) scintillation spectrometry of which procedure manual is provided by the Science and Technology Agency is analyzed on the basis of a train of the actually measured data, and a minimum detectable activity in a routine monitoring is estimated. Judging from the error analysis, the total systematic error of the concentration of 131I in milk is about 10pCi/l, which is mainly attributed to the presence of natural radioactive nuclides except 40K, and the total random error is ±6 pCi/l resulting from the counting error and the deviation in gain adjustment. If we define a minimum detectable activity as the sum of systematic error and three times random error, it would be about 30pCi/l for 131I, But in case some other unexpected nuclides are contained in milk, this method cannot afford to determine the concentrations precisely.

The use of cuprous iodide as a precipitation matrix in the radiochemical determination of 131I in milk.

Abstract As a result of the implementation of the As Low As is Reasonably Achievable (ALARA) philosophy to the nuclear power industry, recent U.S. Nuclear Regulatory Commission (NRC) requirements have prompted high sensitivity radiochemical analysis for the measurement of 131I in milk. The most recognized and commonly employed technique incorporates costly palladium iodide as the final precipitate in the radiochemical purification of the iodine chemical species. The procedure presented in this paper outlines the many advantages of using cuprous iodide as the final precipitate. These include lower cost per analysis, consistent recoveries, better precipitate matrix and good self absorption characteristics. Typical lower limit of detection values and operating characteristics obtained for high sensitivity (3-y analysis as well as gas proportional counting and a comparison of radiochemical and Ge(Li) spectrometric results for environmental samples collected during a recent Chinese weapons fallout incident are presented.

Determination of Extremely Low-Level Radioiodine in Milk

The determination procedure for extremely low-level radio-iodine (131I) in milk ( (23) × 10-9 μCi/ml) which corresponds to 15 mrem/yr of exposure dose for thyroid of a critical person (i.e. a baby) were published recently by both United States Atomic Energy Com-mission and Battelle Pacific Northwest Laboratories. However, error of determination, lower limit of detection and time required for preconcentration and radiation counting were not shown. Therefore we examined these conditions for those two kinds of methods to know whether they are useful for practical performance or not.(1) Recovery of iodine in milk was about 7075 % in both methods.(2) Lower limit of detection of 131I in milk was 6.7 x 10-11 μCi/ml with 30.4% of CV for counting. The determination conditions are : (1) sample volume 4l, (2) counting time 1, 000 min (16 2/3 hr), (3) iodine recovery 70 (4) efficiency of β-ray counting 30 %, background counting 0.8 cpm.(3) In case of two-sample treatment in parallel, it took about 1.52 days for preconcentration procedure, and about 45 days for over-all determination.(4) From the result mentioned above, it was clarified that extremely low-level radioiodine in milk which corresponds to 15 mrem/yr could be practically carried out by the both methods with experimental conditions mentioned in (2).

131-I discharges from an operating boiling water reactor nuclear power station.

A series of radiological surveillance studies was conducted at Dresden Nuclear Power Station by the Radiological Engineering Laboratory of the Division of Environmental Radiation which provided data on 131I concentrations observed in the plant, the plant's effluent, and the environment. Based on the Dresden study data, an evaluation is made in this paper of the public health significance of 131I discharges from BWR nuclear power plants. The in-plant barriers to the transport of 131I through a BWR nuclear power plant to the site environs were found to function at a high efficiency. As a result, the critical phase of the environmental surveillance program for Dresden, a BWR without gaseous holdup, was concluded to be the submersion dose from noble gases, not 131I in milk. For a BWR nuclear power plant employing gaseous holdup, it was concluded that the ingestion 131I dose may be more limiting than the submersion dose from noble gases.

Metabolism of Radioiodide by Lactating Goats Given Iodine-131 for Extended Periods

Twenty-two goats were given twice-daily doses of 131I to determine distribution of radioiodine into milk, urine, feces, and thyroids as these animals approached steady state. For 16 goats on the control diet 36.7 and 5.6% of a daily dose of 131I per liter was found in the milk and plasma, respectively. The 131I milk-plasma ratio was 7.6. Supplementing the control diet with 4mg of iodine per day resulted in a reduction of thyroid 131I and an increase in milk 131I in milk, whereas 1.2g of KI per day markedly reduced the 131I in milk and reduced the M/P ratio by a factor of 10. Perchlorate, fluoroborate, thiourea, Chlorothiazid, and thyroxine reduced the iodine concentration in milk. Though the ability of the goat to concentrate iodide in milk is greater than for the cow, the mechanisms of concentration appear to be similar.

In Vitro Analyses of the Binding of 131I-Iodide to Milk Protein

The experiments reported here were carried out to study the in vitro binding of 131I to bovine milk protein and the factors influencing this binding. Incubation of inorganic carrier-free 131I-iodide with fresh raw milk at 37C for two hours showed as much as 50% of the 131I bound to milk protein, and that as much as 80–90% could be bound in 12–24 hours. It was also shown that this reaction is both time- and temperature-dependent and could be readily blocked by incubation at 8C, boiling the milk prior to incubation, addition of carrier iodide or antithyroid agents such as Tapazole (methyl mercaptan imidazole).Paper chromatography of enzymatic digests of the milk showed the protein-bound 131I in milk is present as 131I-labeled monoiodotyrosine. No other 131I-labeled compounds were observed. These studies would tend to indicate that the binding of 131I-iodide to milk protein involves an enzymatic oxidation of the iodide.