Ensuring the Quality of Toxicity Test Results
James Markwiese, Environmental Standards, Inc.
Toxicity testing represents a powerful line of evidence for assessing impacts from chemical contaminants in the environment. Aquatic and terrestrial toxicity tests are used to determine whether soil, sediment, and water have been impacted by contaminants, to evaluate effects of new and existing chemicals, and to assess whether waste streams (e.g., effluents) can be safely released to the environment. The liability associated with inadequate toxicological characterization, by either over or under-estimating actual toxicity, can be enormous and the quality of toxicity testing is therefore of great importance. The SETAC North America 34th Annual Meeting session "Ensuring the Quality of Toxicity Test Results" provided an overview of quality control and quality assurance measures for state-of-the-art toxicity testing.
This was a timely and important session considering that much of the normative guidance for toxicity testing quality assurance was drafted over two decades ago. Mechanisms were considered to improve the establishment and documentation of quality measures for toxicity testing laboratories. Shortcomings associated with toxicity testing were discussed and included; the insistence on using only standardized toxicity tests, conducting testing because it is possible, not because it will provide necessary information or answer the questions that need answering; endpoints may be limited; and test taxa may not be the same or even similar to those in the real world (different sensitivities); and not applying data quality objectives. Appropriate quality assurance and quality control measures were considered with regard to reducing uncertainty and increasing test acceptability.
Key topics discussed in the session included overviews and context for what toxicity testing can and cannot provide:
- An appreciation for the challenges and opportunities that have been made in recent years for testing soils and sediment
- Important new developments on the maintenance of standard test organisms and standardized artificial media, particularly with regard to new techniques in culturing test organisms
- Lessons learned and progress made in the conduct and application of tests in meeting test acceptability criteria
- Practical means of dealing with difficult-test chemicals such as poorly soluble compounds
- Standardized and efficient ways to search the results of toxicity testing in the ecotoxicological literature
- Audits for detecting problems before they impact data quality, how they can anticipate future problems and how, where there are no problems, the audit results in a record that the quality assurance system has been thoroughly evaluated and found to be acceptable
Considerable progress has been made in recent years in the field of ecotoxicology and while there are many benefits from toxicity testing, there are also many hurdles to proper implementation. An appreciation for quality testing will help ensure the defensibility of test results in the future.
Author's contact information: JMarkwiese@envstd.com
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