Environmental Biomonitoring - ACS Publications - American Chemical

Chapter 21

Environmental Specimen Banking Contributions to Quality Management of Environmental Measurements 1

Downloaded by STANFORD UNIV GREEN LIBR on October 6, 2012 | http://pubs.acs.org Publication Date: May 5, 1997 | doi: 10.1021/bk-1997-0654.ch021

Rolf Zeisler

International Atomic Energy Agency, Laboratories Seibersdorf, P.O. Box 100, A-1400 Vienna, Austria

Specimen Banking involves the systematic collection and archiving of ecologically relevant biological and environmental samples. It is an effective tool for pollutant trend monitoring by real time and retrospective analysis. Some significant archives of samples have been established during the past decades by several industrialized nations, with the earliest samples dating from the 1960s. The value of these archives lies in the planned and evaluated processes for collection, preparation, storage and analysis of the samples. In particular the incorporation of pre-sampling, sampling and transport and storage in the analytical process has provided accurate and traceable data. The value of these quality measures is exemplified with applications in the US National Biomonitoring Specimen Bank, where program performance was studied and where samples of human livers and of marine organisms and sediments were analyzed. Selected results of these studies are included in the discus sion. Environmental data are collected with substantial efforts around the globe. Their purpose is multi-fold: They serve the elucidation of environmental phenomena and are the basis of scientific research on the changes in nature through anthropogenic activities. They are used to identify problems that may threaten ecological and/or human health. They are the basis of regulatory control in the environment and they can support detective actions for the identification of illicit and unknown or unintended input in the environment. The basic requirements for all these uses of environmental data are the same: the qualitative identification must be possible with an accepted degree of certainty and the quantitative value must be generated within accepted limits of uncertainty. In short, environmental data must be of such quality that makes them useful for a given purpose, that assure the absence of defects and that is worth the price. The quality of the environmental data is impacted by many factors that are not necessarily controllable through individual efforts. Therefore considerations of these factors during the planning of such programs and projects are necessary. A prominent factor is obviously the cost of providing the data, but obtaining higher quality (for a 1

Current address: National Institute of Standards and Technology, REACT-B125, Gaithersburg, MD 20899

© 1997 American Chemical Society

In Environmental Biomonitoring; Subramanian, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1997.


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price) is certainly a cost-effective measure. Unrealistic regulations, such as the requirement for detection of extremely low levels may increase the cost or alternately result in low quality of data. In general, the need to determine ever lower levels of substances impacts the cost and the quality of the relevant results. Furthermore, political factors may significantly impact the quality of environmental data through pressure for rapid answers or frequently changing priorities, and last but not least, the socio-economic environment may suppress the desire for quality data. To further complicate the task, it has become necessary in environmental measurements, for example in ecosystem monitoring and biological monitoring, to involve many scientific disciplines in a measurement program. An approach to the measurement would involve the design of a model, the selection of an appropriate sample population, the sampling, transport and storage, the preparation for analysis and the actual determinations, the calculation of results, and dissemination of data and their interpretation. Figure 1 displays, on an arbitrary scale, an individual error potential in relation to neighboring steps, if each steps would be controlled separately. It must be also considered that nowadays quality assurance guidelines are readily available for the analytical steps (7), therefore considerably minimizing the error potential for the central

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Figure 1 The environmental measurement process and likely extent of error, on an arbitrary scale, for the individual steps of the process compared to the analytical measurement error, most likely the smallest error.



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"classical" analytical activities. Obviously, a sectoral approach bears the risk of deviating from the controllable small error potential of the central analytical steps to encounter large uncertainties in the resulting environmental data. Therefore interdisci plinary co-operation is the key to minimize the errors in environmental measurements, together with an expansion of the principles of quality assurance to all steps of the environmental measurement approach. These considerations on the quality of environ mental measurements have been a paramount factor in the early steps of the development of environmental specimen banking approaches (2). Since the early discussions on specimen banking more than twenty years ago (3), the archiving of environmental samples has become an accepted concept in environmental monitoring strategies. Many scientists, institutions, and several countries are using environmental specimen banking as an attractive and cost-effective contribu tion to the investigative tasks in a system of environmental monitoring. A specimen bank provides a systematic historical record for the evaluation of samples collected in environmental, ecological, or human studies. Specifically, a specimen bank fulfills the following objectives: relevant and well characterized samples are preserved for extended time periods without changes; samples are collected in anticipation of changes in the environment and/or changes in anthropogenic input for deferred assay; current pollution studies can refer to historical samples and baseline data to determine trends over time; a comprehensive approach is implemented for the selection, collection, analysis, and evaluation of samples; sufficient material is available to allow "matrix search", "fingerprint analysis", or "key component" directed comprehensive evaluation; and banked sample portions are available for re-analysis to assure previous results. In these capacities, a specimen bank can serve as an integral part of an ongoing monitoring program or develop its own strategies for validated environmental monitor ing that should be made part of the assessment of environmental status. The association of such a program with leading analytical institutions and environmental organizations will further assure the relevance of data and samples. The above discussions have been the guiding principles during the scientific investigations on the feasibility of the specimen bank concept. In pilot programs for the establishment of specimen banks, all aspects of the analytical approach (Figure 1) have been considered in interdisciplinary research (4, 5). These investigations resulted in guidelines and protocols or standard operating procedures for each step from the development of the investigative model to the evaluation of the data. Examples of these achievements are presented below; many of the procedures have found their way as standard procedures in environmental analytical chemistry world wide for technical assurance of the quality of analytical data. It should be noted that today's principles of total quality management have been developed over a similar time frame as the technical achievements and quality measures of the specimen bank approach; their combination in the implementation of regular specimen banking as part of ecological monitoring is the basis of documented and validated environmental data that are provided to national monitoring efforts (6). Technical Concepts for Improved Quality The NIST Specimen Bank. In 1979 a special clean room facility was completed at the National Institute of Standards and Technology (NIST), then the National Bureau of Standards (NBS) (7). This facility was among the first of its kind to be implemented for analytical chemistry. It consists of a class 100 clean room that is divided in two



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parts for consideration of inorganic and organic analytical work, both parts equipped with work benches and ancillary equipment made from materials considered noncontaminating for the respective analyses, i.e., acrylic and plastics in the inorganic section, glass and stainless steel in the organic section. The storage area is adjacent to the analytical clean room and complies to a class 10000 standard. It is equipped with compressor type freezers for storage at -25°C and -80°C and with liquid nitrogen freezers for storage at about -150°C. The selection of materials and implements for sampling and storage was based on extensive research work concerning the transfer to and loss from the investigated samples of components (pollutants) of interest. The concept of the protection of the composition of the sample through technical installa tions, advanced procedures, and careful choices of materials was made a guiding principle in the specimen bank. Some of these are described in more detail below. Similar facilities have been put into operation by other specimen banks (6, 8). Sample collection, transport and storage. Because of the extremely low levels of trace elements and organic pollutants found in most environmental samples, extreme caution must be exercised during sample collection and processing to avoid contamina tion and losses. The guiding principle is to attain control of the sample as quickly as possible when removing it from the natural environment. This is done under "clean and sterile conditions" that are to be achieved even in remote sampling locations. Obvious ly, gradual differences exist between sampling indoors in an autopsy room or in a marine research lab on board a ship, or in the field on an ice flow; consequently, the risks for contamination are different. But, by minimizing the time the sample is exposed to the environment, subsampling under controlled condition, and sealing the sample in the sample container as well as flash freezing after this process, the risk of change in the composition of the original sample is significantly minimized. Once frozen, the sample is transported at liquid nitrogen temperature (or in some instances on dry ice) to the specimen bank facility and stored. The sample never leaves this low temperature until the actual preparation for analysis. Special attention has been given to the sampling implements and containers. Implements made from pure metals or compounds (e.g., titanium, fused silica, Teflon) minimize possible contamination to one element or compound and exclude most other common contamination risks. In particular, Teflon was found to be well suited for purposes of minimizing inorganic and organic contami nation. It also exhibits excellent properties for cold storage, as it does not become brittle, and it is commercially available in a wide variety of containers, bags, and solid bulk material for the fabrication of implements. Sample preparation and analysis. Sampling for trace analysis is a major concern when quality analytical results are required. The reduction of a bulk sample to a laboratory sample (test portion) suitable for the analytical technique employed often introduces errors caused by contamination, loss, or sample inhomogeneity. These errors may become the limiting factor in achieving precise and accurate analytical results. An efficient and contamination-free homogenization procedure for biological materials was found in the brittle fracture technique (9), the cryogenic homogenization of bulk samples with various types of mills. This technique permits the use of Teflon, for example in ball and disk mills, that will not introduce additional sources of contamination (JO). Other types of mills for larger size samples and continuous operation, fitted with titanium or Teflon are also used in specimen banking (77). Employment of these contamination-free devices for size reduction and homogenization of biological tissues at cryogenic temperatures also reduces loss of volatile components and possible changes in composition during the size reduction step. The size reduction and homogeneity is essential for the effective use of analytical techniques and the preservation of specimen bank material.



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The determinations of inorganic and organic constituents may involve significantly different sample preparations for the respective analytical measurements, but in taking the test portions from the same deep-frozen aliquots of a sample, the sample history being the same to this point, the end results are assured to be compatible. In the NIST specimen bank analytical work, comprehensive approaches are used to arrive at very complete data sets of high quality. In the inorganic analytical work, combinations of multi-element techniques, often applied to the same small test portion (typically 250 mg dry sample) of a specimen sample have covered all elements of environmental concern, as well as a large number of the biological micro and trace elements as possible indicators of health or nutrition (72, 13). Care has been taken to assure that element concentrations determined by more than one technique come to acceptable agreement. This involved the application of proven methods that can fulfill the requirements of quality assurance measurements. This agreement of different techniques on many individual measurement points allows inference as to the quality of results that may be obtainable only by one technique. The organic determinations focussed initially on organochlorine pesticide residues and PCBs; later, polycyclic aromatic hydrocarbons, dioxins, furans, etc., have been included. Because organic methods are not as varied as inorganic (e.g., in extraction or digestion methods), quality is mostly assured through the exchange of test portions of the same samples among qualified laboratories (74). In any case, the analyst is in a position to draw from the banked material for additional analytical work and quality assurance, since preparation of the test portions and storage conditions assures that the newly-analyzed material is equal to the previous.

Guidelines and Protocols to Assure Quality A specimen is a sample representative of an ecosystem, population, site, or individual organism selected for inclusion in the specimen bank based on the following criteria: specimen bears ecological and biological significance; specimen is a (long-term) accumulator; samples are available over long time periods and can be collected in many regions; undisturbed samples are available; and specimens may be individual or pooled samples. Each type of specimen considered for monitoring and banking has its own requirements for the analytical process, consequently, the analytical protocol must be developed and evaluated in conjunction with the purpose, design, and implementation of the monitoring program. To exemplify this approach, this paper refers to the initial work on human liver specimens of the US National Environmental Specimen Bank (75). The procedures and protocols developed in this early stage of specimen banking have found widespread use, e.g. in the collection of tissue samples from marine mammals (76) or roe deer (77). As recognized before (Figure 1), the largest error potential exists in the numerous pre-analysis steps. The selection of human liver (or marine mammal and deer livers in the later programs) as an environmental indicator was driven by the fact that a sizable sample of macroscopic homogeneity and good anatomical description could be taken in a manner that excludes or minimizes initial intrusion into the sample. The procedure to excise the whole liver without distortion was developed with medical examiners and implemented with appropriate training of autopsy personnel on handling and sub-sampling. The sampling protocol was designed to avoid contaminating the sample by either inorganic or organic constituents. The protocol specifies all items that were used, such as pre-cleaned, dust free Teflon sheets, bags and storage jars, titanium knives for dissection, dust-free vinyl gloves, high purity water; it also specifies the sequence of all steps from excision to sealing the sample in its container, flash freezing, and recording all relevant information. The frozen samples were then kept at -150°C



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until used for analysis. The field sampling procedures are supported by strict proce dures for the preparation of implements and auxiliary materials (18). Sample informa tion as well as sampling, storage, and handling records accompany the sample in all steps of banking and analytical work. Reporting of results is therefore assured to be traceable to the original sample. The active specimen bank programs have prepared publications and manuals that make these procedures available to researchers and monitoring programs world wide. Thus harmonized approaches for the particularly critical pre-analysis operations are available that will provide comparable analytical data which fulfill many quality requirements. The available information extends from procedures for individual sample types as mentioned above to manuals describing the collection of a large number of biota and other environmentally-related materials, such as the Manual for Nordic Countries: Nordic Environmental Specimen Banking (79).

Quality Management in Environmental Analytical Chemistry The specimen banks have played a leading role in implementing quality management principles in environmental analytical chemistry by examining all steps of the analytical process and applying the principles of documentation, repeatability, and traceability to these steps. It has been essential that premier research institutions in analytical chemistry participated in the development of the quality principles, long before the implementation of guidelines for analytical laboratories have become common instru ments in the daily work of environmental assessment. The specimen banks have created inventories of samples that are meticulously characterized and preserved and have provided environmental baseline data against which trends in environmental pollution can be reliably measured. The achievements in improved data quality are illustrated with the data set obtained on 120 human livers from the NIST Specimen Bank. The main features of these high quality data are illustrated in Figure 2. Data were obtained with similar precision and accuracy for more than thirty elements ranging in concentration levels over nine orders of magnitude, including several elements where limited or no data had been available until this work. It was found that concentration ranges for some essential trace elements were narrower than previously reported and also that certain pollutant elements were found to be an order of magnitude lower than reported before. Even small trends in environmental exposure, such as the declining levels of lead in the human lead body burden can be traced based on such reliable data, though the number of investigated specimens is relatively small (20). Specimen banking has made a fundamental contribution to environmental analytical chemistry by including the history of a sample in the analytical process to provide controlled and traceable results. It preserves samples for retrospective analysis for quality assurance and the provision of missing data. Thus specimen banking is a self-sustaining management system for high quality environmental data. The overall picture of changes in chemical composition in the environment no longer remains murky, unclear and fuzzy because of a significant lack of data especially from the past. Relevant questions concerning a potentially hazardous chemical such as: "When and where did it first enter the environment?", and "Where did it come from?" will find answers since data, samples or approaches for the analytical investigation exist. In view of the hundreds of new chemicals that are introduced every year and the tens of thousands that are in use in industry, agriculture, human consumption, etc., it is necessary to complement the routine approaches for monitoring with a system that provides for trend and anticipatory monitoring, as well as action plans and activities that are adequate for any test in environmental assessment. The existing Specimen Banks have illustrated their capacity in this field fulfilling all requirements for quality of environmental data.


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Figure 2 Notched box plots of the results of element determinations in 120 human livers from the NIST Specimen Bank. Literature Cited 1.

2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

ISO/IEC Guide 25, General Requirements for Testing Laboratories, 3rd rev.,

Geneva, Switzerland, 1990. Wise, S. Α.; Zeisler, R. Environ. Sci. Technol. 1984, 18, 302A-307A. Luepke, N . P., Ed. "Monitoring Environmental Materials and Specimen Banking"; Martinus Nijhoff Publishers: The Hague, the Netherlands, 1979. Berlin, Α.; Wolff, A. H.; Hasegawa, Y., Eds. "The Use of Biological Specimens for the Assessment of Human Exposure to Environmental Pollut ants"; Martinus Nijhoff Publishers: The Hague, the Netherlands, 1979. Lewis, R. Α.; Stein, N.; Lewis, C. W., Eds. "Environmental Specimen Banking and Monitoring as related to Banking; Martinus Nijhoff Publishers: The Hague, the Netherlands, 1984. Kemper, F. H.Sci. Total Environ. 1993, 139/140, 13-26. Moody. J. R. In "Pilot Program for the National Environmental Specimen Bank - Phase I"; Harrison, S. H., Zeisler, R.; Wise, S. Α., Eds.; EPA-600/1-81-025, 1979, pp. 8-18. Schladot, J. D.; Stoeppler, M.; Schwuger, M. J. Sci. Total Environ. 1993, 139/140, 27-36. Iyengar, G. V.; Kasparek, K. J. Radioanal. Chem. 1977, 9, 301-16. Zeisler, R.; Langland, J. K.; Harrison, S. H. Anal. Chem. 1983, 55, 2431-34. Schladot, J. D.; Backhaus, F.W. In: Progress in Environmental Specimen Banking NBS/SP-740 1988, U.S. Government Printing Office, Washington, DC, pp 184-193.


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Zeisler, R., Stone, S.F., and Sanders, R.W. Anal. Chem. 1988, 60, 27602765. Zeisler, R., Ostapczuk, P., Stone, S.F., Stoeppler, M. Sci. Total Environ. 1993, 139/140, 403-410.

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Wise, S. Α. Ρroc. Coastal Zone '93, 1993, 2531-2541.

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Zeisler, R.; Harrison, S. H.; Wise, S. A. Biol. Trace Elem. Res. 1984, 6, 3149. Becker, P. R.. Wise, S. Α., Koster, B. J., Zeisler, R., Alaskan Marine Mammal Tissue Archival Project: Revised Collection Protocol, NISTIR 4529, National Institute of Standards and Technology, Gaithersburg, USA, 1991. Holm, J. Sci. Total Environ. 1993, 139/140, 237-249. Moody, J. R.; Lindstrom, R. M. Anal. Chem. 1977, 49, 2264-67. Nordic Environmental Specimen Banking - Methods in Use in ESB: Manual for Nordic Countries. Nordic Council of Ministers, Copenhagen, Denmark, 1995. Zeisler, R., Greenberg, R.R., and Stone, S.F. J. Radioanal. Nucl. Chem. 1988, 124, 47-63.

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