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| REVIEW ARTICLE |
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| Year : 2016 | Volume
: 39
| Issue : 2 | Page : 53-61 |
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Role of the IAEA's ALMERA network in harmonization of analytical procedures applicable worldwide for radiological emergencies
Aurelien Pitois1, I Osvath2, S Tarjan1, M Groening1, D Osborn2
1 International Atomic Energy Agency, Environment Laboratories, Seibersdorf, Austria
2 International Atomic Energy Agency, Environment Laboratories, Monaco
| Date of Web Publication | 13-Sep-2016 |
Correspondence Address:
Aurelien Pitois
International Atomic Energy Agency, Environment Laboratories, 2444 Seibersdorf
Austria
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0972-0464.190396
The International Atomic Energy Agency (IAEA) coordinates and provides analytical support to the worldwide network of Analytical Laboratories for the Measurement of Environmental Radioactivity (ALMERA). The goal of ALMERA is to provide timely and reliable measurement results of environmental radioactivity in routine monitoring and emergency situations. Finding and choosing the most adequate analytical procedures for environmental monitoring can be a challenge for laboratories due to a wide variety of technologies available and the rapid developments in this field. To respond to this challenge, the IAEA has included within its ALMERA activities, the development and validation of a set of procedures for the determination of natural and anthropogenic radionuclides in environmental samples, for both routine and emergency environmental monitoring. Methodological harmonization, in turn, leads to enhanced worldwide comparability of environmental radioactivity measurement results. The respective analytical procedures are developed by expert groups from ALMERA member laboratories and validated through several ALMERA laboratories worldwide according to a comprehensive methodology. In addition to sequential analytical procedures for routine environmental monitoring, rapid procedures applicable for radiological emergencies have been developed and validated for the determination of americium and plutonium radioisotopes in soil and sediment samples, radiostrontium in milk, and radium isotopes in drinking water. Currently, the development of rapid procedures for radiostrontium analysis in soil and seawater is underway, partly prompted by the interest for high throughput procedures following the analytical burden of laboratories after the Fukushima Daiichi NPP accident. Keywords: ALMERA, analytical procedures, environmental radioactivity, network of laboratories, radiological emergencies
How to cite this article:
Pitois A, Osvath I, Tarjan S, Groening M, Osborn D. Role of the IAEA's ALMERA network in harmonization of analytical procedures applicable worldwide for radiological emergencies. Radiat Prot Environ 2016;39:53-61 |
How to cite this URL:
Pitois A, Osvath I, Tarjan S, Groening M, Osborn D. Role of the IAEA's ALMERA network in harmonization of analytical procedures applicable worldwide for radiological emergencies. Radiat Prot Environ [serial online] 2016 [cited 2023 May 28];39:53-61. Available from: https://www.rpe.org.in/text.asp?2016/39/2/53/190396 |
| Introduction | |  |
Terrestrial and marine ecosystems across the globe, and the essential services they provide, are increasingly threatened by climate change, natural catastrophes, the destruction of habitat, and pollution from various anthropogenic activities including accidental or intentional release of radioactivity. The ability to accurately measure the impact of these adverse environmental effects is crucial not only in determining the extent of damage but also to assist in remediating it.
To address growing needs for reliable and timely measurements of environmental samples, a worldwide network of Analytical Laboratories for the Measurement of Environmental Radioactivity (ALMERA), was formed under the aegis of the International Atomic Energy Agency (IAEA). At the end of 2015, this network consisted of 154 laboratories in 85 countries. Its main goal is to pool the resources of participating laboratories to provide reliable and timely determination of radionuclides in samples used for both routine and emergency environmental monitoring.
The IAEA supports the ALMERA laboratories in their routine and emergency response environmental monitoring activities by organizing proficiency tests and interlaboratory comparison exercises, developing validated analytical procedures for environmental radioactivity measurement, and organizing training courses and workshops. The network also acts as a forum for sharing knowledge and expertise.
Tested and validated analytical procedures are essential tools for the production of reliable and comparable measurement results that are key requirements for any decision based on analytical measurements. Routine environmental radioactivity monitoring is required to ensure the protection of the citizens and the environment from harmful ionizing radiation, as well as in the enforcement of national regulations. Emergency sampling and environmental radioactivity measurements using rapid analytical procedures are very important tools to provide authorities with reliable and timely information on the radionuclide content in environmental samples collected in affected areas.[1],[2] The information provided by analytical laboratories support decision-making and steps taken by governments to protect their citizens.
Within this context, a growing set of analytical procedures for the determination of radionuclides in environmental samples has been developed and validated within the IAEA's ALMERA activities. These validated procedures contribute to methodological harmonization, leading to enhanced worldwide comparability of environmental radioactivity measurement results. For ease of use, these procedures are comprehensive, clearly formulated, and readily available to both the analyst and the customer.
In this paper, we present an overview of the ALMERA analytical method development activities for radiological emergencies and the plans for further development in the field. Special emphasis is given on the methodology used for the development of such procedures. Existing analytical procedures are examined and their role in enhancing methodological harmonization worldwide discussed.
| Methodology Used for Development And Validation Of Almera Analytical Procedures | | |
Analytical method development and validation rely on a collaborative effort of the ALMERA network laboratories. Procedures for routine and emergency monitoring are developed according to the comprehensive protocol shown in [Figure 1], which involves selection, development, and validation phases before publication of the developed and validated analytical procedure as an IAEA document. Those IAEA documents, published in the IAEA Analytical Quality in Nuclear Application Series (https://nucleus.iaea.org/rpst/ReferenceProducts/Analytical_Methods/index.htm), are available as pdf files free of cost, as a service to the scientific community. | Figure 1: Methodology used for the development and validation of ALMERA analytical procedures
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Selection and assessment of candidate procedure phase
Important radionuclides in routine and emergency monitoring, and analytical needs for their measurement in ALMERA member laboratories are identified at the annual ALMERA coordination meeting. Representatives of ALMERA member laboratories meet in regional working groups and discuss their respective analytical needs at the regional level. The regional needs are then compiled and further discussed at the thematic ALMERA analytical method development working group, and finally, a priority list for upcoming ALMERA method development activities is agreed among ALMERA member laboratories. Based on the established priority list and additional criteria such as feasibility, availability of suitable material for the validation phase, and availability of resources, a decision is taken on the upcoming ALMERA method development activity.
Following the method selection process led by the ALMERA member laboratories, the IAEA, in its coordinating role, launches a call to all ALMERA member laboratories to express interest in taking part to the ALMERA expert group involved in the development of the given analytical procedure. The expert group consists of the IAEA Environment Laboratories, the Korea Institute of Nuclear Safety as IAEA Collaborating Centre for the analytical method development, and in most cases, of three ALMERA member laboratories having a significant experience in the field of the method development activity and an excellent record in IAEA proficiency test exercises. For similar expertise, geographical balance is also considered for worldwide representability of the expert group. The nominated expert group proceeds to an extensive review of papers in the scientific literature and defines the selection criteria and requirements for the analytical procedure. For procedures applicable worldwide for radiological emergencies, primary criteria are typically the rapidity of the procedure, the efficiency of the radiochemical separation, and the potential use of the procedure in a wide range of laboratories. Primary selection criteria may also include the need to determine radionuclides of shorter half-life, which may not be relevant for routine environmental monitoring but are of primary importance immediately after the emergency event. Secondary selection criteria are typically the detection limit and the cost-effectiveness of the procedure. Whereas those criteria are of primary importance for routine environmental monitoring, those are not considered of primary importance in emergency situations. Secondary selection criteria may also include a high throughput for the procedure, i.e., to be able to handle a significant number of samples in parallel, since in case of emergency, it is expected that a high number of samples will be provided to the laboratory in a short time frame. It is also recommended to select procedures not using fuming nitric acid, since in addition to safety issues in handling such materials in the laboratory, import restrictions are present in many countries around the world. Requirements associated to the identified selection criteria are then established by the expert group. Analytical procedures from the literature survey are assessed versus the selection criteria and requirements, and a limited number of candidate procedures are identified for further investigation based on consensus agreement from the members of the expert group. The candidate procedures are thoroughly studied by each member of the expert group. This involves careful study of the scientific papers as well as assessment of analytical procedures in the laboratory. A decision on the most suitable procedure, with modification if required, is then taken considering the comments from the expert group members, and a first draft of the developed procedure, including all detailed steps, is written for use in the method validation phase.
Method validation phase
Following the method development process led by the ALMERA expert group, the IAEA launches a call to all ALMERA member laboratories to express interest in taking part to the validation phase of the developed procedure. The ALMERA method validation group consists of a representative number of laboratories with geographical balance, which carry out on a routine basis analyses in the field of the developed analytical procedure. Those are provided with suitable validation samples and calibration solutions prepared and shipped by the IAEA for measurement using the developed analytical procedure. Each laboratory participating to the method validation measures the validation samples and reports their measurement results, including uncertainty estimation, to the IAEA for data analysis. The validation phase is taking place in accordance with ISO guidelines. Figures of merit, such as accuracy, precision, repeatability, reproducibility, decision threshold, and detection limit, are calculated, and limitations of the analytical procedure are identified.
Method publication phase
An IAEA publication on the developed and validated procedure is then drafted, and after review by all relevant ALMERA laboratories, it is submitted to the IAEA publication committee for publication in the IAEA Analytical Quality in Nuclear Application Series. For ease of use, the published procedures are comprehensive, clearly formulated, and readily available to all laboratories. They follow a given template and include scope of the procedure, normative references, responsibilities, principle, equipment and chemicals, detailed procedure, expression of results, including uncertainty estimation, and all results from the validation of the procedure. All relevant figures of merit and any limitations to the analytical procedure are also included. Owing to the comprehensiveness of the used methodology, approximately 2 years of work are required from the selection of the ALMERA method development activity to the publication of the developed and validated analytical procedure as an IAEA document.
| Almera Developed and Validated Analytical Procedures Applicable Worldwide For Radiological Emergencies | | |
A set of procedures for the determination of natural and anthropogenic radionuclides in environmental samples in emergency situations have been developed and validated within the frame of the ALMERA method development activity. They respond to different scenarios, i.e., radiological emergencies from nuclear facilities and radioactive contamination from non-nuclear facilities.[3] The list of rapid procedures developed and validated in the frame of the ALMERA method development activities is given in [Table 1]. They are related to the determination of americium and plutonium radioisotopes in soil and sediment samples,[4] radiostrontium in milk,[5] and radium isotopes in drinking water.[6] Currently, the development of rapid procedures for radiostrontium analysis in soil and seawater is also underway. Plutonium, americium, and radiostrontium have been identified as strategically important in an accidental release scenario as they would be responsible for the majority of the alpha and beta contamination of the environment. Significant effort was dedicated to developing procedures for their determination.[7],[8] | Table 1: Rapid analytical procedures developed and validated in the frame of the ALMERA method development activities
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Rapid procedure for americiuma and plutonium in soil/sediment
Americium and plutonium nuclides are artificial radionuclides produced in the nuclear fuel cycle, which may be released into the environment in case of accident at nuclear facilities such as nuclear reactor facility or reprocessing plant. The principal pathway of contamination of the environment is through deposition of those radionuclides on the ground. In an emergency situation, a rapid procedure for detecting americium and plutonium nuclides in soil samples is a very important tool for identifying any potential contamination of the environment through this pathway and for providing reliable and timely information to authorities on the radionuclide content in soil samples collected in the affected areas. The information provided by the laboratories helps the authorities in their decision-making process and in taking appropriate actions to ensure the protection of the population from any potential direct exposition to radiation. In this frame, a rapid procedure for the determination of americium and plutonium radionuclides in soil samples [4] was developed and validated that can be used in emergency situations. This procedure is also suitable for the determination of americium and plutonium radionuclides in sediment samples in case of any potential contamination of the marine environment following a radiological emergency.
The analytical procedure is based on the digestion of the soil/sediment matrix, on preconcentration of the americium and plutonium radioisotopes using selective co-precipitation, on the separation of americium and plutonium radioisotopes using extraction chromatography, and on a micro-co-precipitation step for the preparation of the sources. The 238 Pu,239+240 Pu, and 241 Am radioisotopes are then determined using alpha-particle spectrometry. The figures of merit of the developed and validated rapid analytical procedure for the determination of plutonium radioisotopes and 241 Am in soil and sediment samples using alpha-particle spectrometry [4] are given in [Table 2]. Typical spectra of 238 Pu and 239+240 Pu radioisotopes obtained by alpha-particle spectrometry after radiochemical separation using the developed rapid procedure are shown in [Figure 2]. The procedure is suitable for measuring 238 Pu,239+240 Pu, and 241 Am in soil and sediment samples in emergency situations. Measurement results can be provided to authorities within a 24 h period for massic activities ranging from 5 to 5000 Bq/kg. The analytical procedure is robust and highly selective; it provides accuracy, expressed as relative bias, in the range of 7–10% for the measured radionuclides. | Table 2: Figures of merit of rapid analytical procedure for determination of Pu radioisotopes and 241Am in soil and sediment samples using alpha-particle spectrometry
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 | Figure 2: Typical spectra of 238Pu and 239+240Pu radioisotopes obtained by alpha-particle spectrometry after radiochemical separation (counts as a function of channels)
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Rapid procedure for 89Sr and 90Sr in milk
Radiostrontium is one of the most biologically hazardous radionuclides produced in nuclear fission processes. If released into the environment, radiostrontium becomes incorporated into the calcium pool due to its chemical properties close to those of the calcium element. Radiostrontium can then enter the human body through one of the principal pathways: soil to plant to cow's milk to humans. Milk, as a major constituent of children diet, is an important indicator of the transfer of radionuclides from the environment to humans. Therefore, in emergency situations, the rapid analysis of radiostrontium in milk is essential to protect humans from radiation exposure due to consumption of contaminated milk. The analysis time is an important economic factor, as rapid identification of contamination with radioactive material helps decision makers introduce protective measures according to the intervention levels. In emergency situations, two strontium radioisotopes,89 Sr and 90 Sr, have to be considered due to their respective half-lives, i.e., 51 days for 89 Sr and 29 years for 90 Sr. It has to be noticed that whereas only 90 Sr radioisotope needs to be monitored for routine environmental monitoring, since 89 Sr decays quickly in the environment, in emergency situations, and immediately after the release,89 Sr needs to be monitored since it is released in higher massic activity than the 90 Sr radioisotope, and therefore primarily contributes to the dose to the public. In real samples collected under emergency conditions, the 89 Sr/90 Sr ratio is expected to vary between 5 and 30 depending on the characteristics of the accident. In this frame, a rapid procedure for the simultaneous determination of 89 Sr and 90 Sr in milk samples [5] was developed and validated that can be used in emergency situations.
The analytical procedure is based on the use of cation exchange and extraction chromatography resins and on selective co-precipitation steps. The isotopes 89 Sr and 90 Sr are then determined by liquid scintillation counting. The figures of merit of the developed and rapid analytical procedure for the simultaneous determination of 89 Sr and 90 Sr in milk samples using liquid scintillation counting [5] are in given in [Table 3]. The analytical procedure is suitable for measuring simultaneously 89 Sr and 90 Sr in milk samples for 89 Sr/90 Sr massic activity ratios up to 30. Measurement results can be provided to authorities within a 24 h period for a large range of massic activities. The analytical procedure provides accuracy, expressed as relative bias, in the range of 3% for 89 Sr and 10% for 90 Sr for a 89 Sr/90 Sr massic activity ratio of 5. Uncertainty on measurement results is increasing with increasing 89 Sr/90 Sr massic activity ratios. The analytical procedure is straightforward and does not contain any complex steps or require any highly specific equipment items, and therefore can be carried out in most radiochemical laboratories worldwide in emergency situations. In relation to needs identified following the Fukushima Daiichi NPP accident, development of rapid procedures for radiostrontium analysis in soil and seawater is underway following the methodology mentioned above. | Table 3: Figures of merit of rapid analytical procedure for simultaneous determination of 89Sr and 90Sr in milk samples using liquid scintillation counting
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Rapid procedure for 226Ra and 228Ra in drinking water
Radioactive contamination of the environment can also occur from non-nuclear facilities.[3] Substances with enhanced concentrations of natural radionuclides can be present at industrial production sites and in the environment as a result of industrial or mining activities.[9] These substances are referred as Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM). Increasing interest has been shown by national and international regulatory bodies in regulating radioactivity levels in those industries and in consumer products for the protection of human health and the environment. Among radionuclides naturally present, the two radium radioisotopes,226 Ra and 228 Ra, are very significant from a radiological protection point of view due to their relatively long half-lives, presence in nature as radionuclides from the uranium and thorium decay series, and high dose conversion factors. Due to having similar properties to other elements from Group II such as calcium, they can easily be incorporated into bones and produce short-lived radionuclides of high massic activity in the bones. For the general public, the consumption of food and water containing radium may lead to an accumulation of these radionuclides in the body, contributing to radiological dose.[10] It is, therefore, important to determine radium in drinking water for protecting human health.[11],[12] In this frame, a rapid procedure for the determination of 226 Ra and 228 Ra in drinking water [6] was developed and validated that can be used for screening purpose in emergency situations and routine environmental monitoring.
The analytical procedure is based on the separation of 226 Ra and 228 Ra from interfering elements using PbSO4 and Ba(Ra)SO4 co-precipitation steps. The isotopes 226 Ra and 228 Ra are then determined by liquid scintillation counting. The figures of merit of the developed and validated rapid analytical procedure for the determination of 226 Ra and 228 Ra in drinking water samples using liquid scintillation counting [6] are given in [Table 4]. Typical spectra of 226 Ra and 228 Ra obtained by liquid scintillation counting after selective co-precipitation steps are shown in [Figure 3], illustrating the negligible spectral overlap between 226 Ra and 228 Ra. The analytical procedure is suitable for measuring simultaneously 226 Ra and 228 Ra in drinking water samples for various 226 Ra/228 Ra ratios. Measurement results can be provided to authorities within a 10 h period for massic activities ranging from a few tens of mBq/kg up to several hundreds of Bq/kg. The analytical procedure provides accuracy, expressed as relative bias, in the range of 1–8% for 226 Ra and 5–11% for 228 Ra for 226 Ra and 228 Ra massic activities varying between 0.5 and 3 Bq/kg. Limitations are related to the presence of high amounts of barium (>100 mg/kg) and calcium (>500 mg/kg) in the original matrix. The analytical procedure is straightforward and does not contain any complex steps or require any highly specific equipment items. | Table 4: Figures of merit of rapid analytical procedure for determination of 226Ra and 228Ra in drinking water samples using liquid scintillation counting
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 | Figure 3: Typical spectra of (a) 226Ra and (b) 228Ra obtained by liquid scintillation counting after selective co-precipitation steps, illustrating negligible spectral overlap
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In addition to those analytical procedures applicable for radiological emergencies, sequential procedures applicable for routine environmental radioactivity monitoring were also developed and validated for the sequential determination of radiostrontium, americium, and plutonium radioisotopes in environmental samples,[13] natural radionuclides in TENORM samples from phosphate industry,[14] and polonium in water samples.[15]
| Contribution Of the Iaea's Almera Network To Harmonization Of Analytical Procedures | | |
Tested and validated analytical procedures are essential tools for the production of reliable and comparable environmental radioactivity measurements. For maximum utility, the procedures need to be recognized and accepted by the scientific community, comprehensive, clearly formulated, easily available to all stakeholders, and easily applicable in a large number of laboratories worldwide.
Recognition and acceptance by the scientific community of developed and validated analytical procedures are a very important aspect for enhancing methodological harmonization worldwide. Within this context, it is essential to have a strong involvement of analytical laboratories with recognized expertise and with geographical balance in the development and validation processes. The ALMERA network offers a unique opportunity for this, as the largest environmental network of its kind, with 154 laboratories from 85 countries actively participating to the activities of the network at the end of 2015. The ALMERA analytical procedures are developed by expert groups from ALMERA member laboratories selected according to their well-recognized expertise in the area. They are then validated on a larger scale by ALMERA laboratories representing all regions in the world. This process aims at ensuring the development of state-of-the-art procedures as well as to allow acceptance and recognition of the procedures worldwide. This favors also adoption of the developed and validated procedures in the laboratories involved in the process.
Comprehensiveness of the developed and validated procedures is ensured by the used methodology. The validation phase is as extensive as necessary to ensure robustness and reliability of the procedures and to provide to laboratories all required information for facilitating the implementation of the procedures in their own laboratories. The process is transparent and based on needs identified in laboratories worldwide. The detailed procedure as well as all validation results are provided in a report published as an IAEA document. Publication under the umbrella of the IAEA as an international organization ensures the independence of the developed and validated procedures and facilitates acceptance worldwide of the procedures. All publications are made available free of cost to all interested bodies on the IAEA website for readily availability.
The development and validation of procedures in a large network of laboratories with recognized expertise and geographical balance, the comprehensive methodology implemented, the easy-to-use aspects of the procedures as well the availability of the procedures contribute to methodological harmonization, leading to enhanced worldwide comparability of environmental radioactivity measurement results.
In addition to the publication of the developed and validated analytical procedures, training courses are also organized to train ALMERA laboratories personnel on the procedures directly in the laboratory, leading to additional analytical capacity building for emergency preparedness. In this frame, training courses on rapid assessment methods for environmental radioactivity are regularly organized to reinforce the skills of personnel of the ALMERA laboratories who are interested in enhancing their rapid response capabilities in case of a radiological emergency event. The practice in the laboratory of a rapid analytical procedure validated by the ALMERA laboratories and published by the IAEA is a key element of such training courses. Two training courses were organized in 2014 and 2015 on the practice in the laboratory of the rapid procedure for the determination of plutonium and americium radioisotopes in soil and sediment samples. One training course was organized in 2014 on the practice in the laboratory of the rapid procedure for the simultaneous determination of 89 Sr and 90 Sr in milk samples. In total, 56 staff members from the ALMERA network laboratories were trained in 2014 and 2015 on rapid analytical procedures. These training courses gave the opportunity to laboratory personnel to refresh and update their knowledge, expertise, and skills in their relevant work areas. During the course, participants practice the radioanalytical procedure in a radiochemical laboratory and are taught specific data analysis techniques for the calculation of measurement results and their associated uncertainties. Experts guide the scientists on the key components of the analytical quality work that has to be implemented to reach a conclusive result. The training courses are tailored to the needs of the ALMERA laboratories. They are taking place in conditions as close to real-life conditions to ensure maximum benefit to the participants and to facilitate transfer of the acquired knowledge to the participants' laboratories.
| Conclusions | | |
Good environmental management, as well as public safety, demands the comparability and compatibility of measurement results for activities in which laboratories with different practices contribute. This is especially the case in an emergency situation where a high number of samples are expected to be analyzed in a short time frame and which requires common efforts from several radioanalytical laboratories to provide timely information on the radionuclide content in environmental samples collected in the affected areas. The IAEA, within its ALMERA method development activities, has been significantly contributing to methodological harmonization by developing and validating rapid analytical procedures for the determination of natural and anthropogenic radionuclides in environmental samples. Those validated analytical procedures are very important tools for enhancing worldwide comparability of environmental radioactivity measurement results in emergency situations. Training courses also contribute to the wider application of the developed and validated analytical procedures and facilitate the harmonization of procedures among environmental radioanalytical laboratories. These activities support quality in the assessment of environmental contamination in emergency situations and result in the dissemination of rapid analytical procedures and harmonization among radioanalytical laboratories.
Acknowledgments
The active participation of the ALMERA member laboratories in the ALMERA method development activity is gratefully acknowledged. The IAEA is grateful for the support provided to its Environment Laboratories by the Government of the Principality of Monaco.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]
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