31 No. 4
Reference Matrices: An Essential Tool for Testing Extrinsic Substance Properties
Werner Kördel, et al.
Trends in Analytical Chemistry, 2009
Vol. 28, Issue 1, pp. 51–63
Within a substance-oriented concept in environmental testing (e.g., the European legislation on chemical—REACH—or pesticide and biocide registration) or a preventive approach to environmental protection, the occurrence, fate, and exposure processes and the adverse effects imposed by toxicants have to be elucidated and assessed. This means having to consider processes that depend on the properties of the substance, the properties of the environmental compartments, and the habitat and sensitivity of the organisms tested. To derive tolerable concentrations of substances (pollutants) in environmental compartments (e.g., soils or sediments), it is necessary to measure both intrinsic properties and extrinsic response functions.
The concept of reference matrices does not deal with the “static” physical and chemical properties of a matrix but with dynamic functions (e.g., transformation, sorption or desorption, transport and effects on fauna and flora). It is important to mention that reference matrices are designed for laboratory testing. This means matrices are sampled in a specific environmental compartment, treated, stored, and characterized. By this, the original sample becomes a specific lot of a reference entity (e.g., a true soil). The idea behind the reference system is to reduce the complexity of the natural environment to a level where it becomes controllable from an experimental point of view without losing the ability to commute the results obtained back to the reality of the original environment.
The concept supports standardization in measurement and testing of chemicals in the environmental or in biological systems, thus leading to:
- comparability of experimental data
- traceability to the common reference point, thus introducing the notion of quality control over measurement and testing
- the ability to extrapolate laboratory findings to the “real world” or the natural environment by using models
The concepts and the philosophy of reference matrices were developed within the IUPAC project on reference soils, and their feasibility was proven using this example. Well-defined reference matrices offer interesting perspectives for increasing environmental realism in chemical risk assessment. The legislation and regulation of various groups of biologically active substances, such as pesticides, biocides, and pharmaceuticals, and the new chemical regulation (REACH) emphasizes the need to have available well-defined reference matrices. This need parallels the need to test environmental fate and effects and new materials (e.g., artificially produced nanomaterials).
The concept that we outline provides suitable guidelines for selecting reference matrices. However, we note that agreement on optimal application of reference matrices and interpretation of results obtained in tests using reference matrices needs to be reached between scientists, risk assessors, reference laboratories, and international standard organizations.
For more information and comments, contact Werner Kördel <[email protected]>; Willie Peijnenburg <[email protected]>; or Bernd Gawlik <[email protected]t>.
last modified 1 July 2009.
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