Claxton L D, Douglas G, Krewski D, Lewtas J, Matsushita H, Rosenkranz H
Health Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711.
Mutat Res. 1992 Jan-Mar;276(1-2):61-80. doi: 10.1016/0165-1110(92)90055-e.
The International Programme on Chemical Safety (IPCS) sponsored an international collaborative study to examine the variability associated with the extraction and bioassay of standard reference materials (SRMs) that are complex environmental mixtures provided by the U.S. National Institute of Standards and Technology (NIST). The study was also intended to evaluate the feasibility of establishing bioassay reference values and ranges for the SRMs. Twenty laboratories from North America, Europe, and Japan participated in the study. As part of the mandatory core protocol, each laboratory extracted the organic material from two particulate samples and bioassayed these extracts. A coal tar polycyclic aromatic hydrocarbon (PAH) solution and two mutagenic control compounds were also subjected to bioassay without prior extraction by the participating laboratories. The bioassay used was the Salmonella/microsomal plate incorporation assay. For the optional portion of the study, a laboratory was free to use the SRMs for any type of exploratory research. The primary purpose of the required portion of the study was to estimate the intra- and inter-laboratory variability in mutagenic potencies of the test materials and to determine whether or not the NIST mixtures could be used as reference materials by others performing the Salmonella assay. Repeatability (intra-laboratory variance) of the bioassay results ranged from 16% to 88% depending on the SRM and the bioassay conditions (tester strain and metabolic activation), whereas reproducibility (inter-laboratory variance) ranged from 33% to 152%. Between-laboratory variability was the main source of variation accounting for approximately 55-95% of the total variation for the three environmental samples. Variation in the mutagenic potency of the control compounds was comparable, with the exception of 1-nitropyrene for which the reproducibility ranged from 127% to 132%. In summary, NIST SRMs provided useful materials for an international inter-laboratory study of complex mixtures. By establishing both intra- and inter-laboratory variance for the mutagenicity results for these materials, the usefulness of these SRMs as reference materials for the Salmonella bioassay was established, critical procedures within the bioassay protocol were identified, and recommendations for future efforts were delineated.
国际化学品安全规划署（IPCS）发起了一项国际合作研究，以检验与美国国家标准与技术研究院（NIST）提供的作为复杂环境混合物的标准参考物质（SRM）的提取及生物测定相关的变异性。该研究还旨在评估为这些标准参考物质确立生物测定参考值及范围的可行性。来自北美、欧洲和日本的20个实验室参与了此项研究。作为强制性核心方案的一部分，每个实验室从两个颗粒样品中提取有机物质，并对这些提取物进行生物测定。一种煤焦油多环芳烃（PAH）溶液和两种诱变对照化合物也未经参与实验室预先提取就进行了生物测定。所采用的生物测定方法是沙门氏菌/微粒体平板掺入试验。对于研究的可选部分，一个实验室可自由地将这些标准参考物质用于任何类型的探索性研究。该研究规定部分的主要目的是估计测试材料诱变性效力的实验室内和实验室间变异性，并确定其他进行沙门氏菌试验的机构是否可将NIST混合物用作参考物质。生物测定结果的重复性（实验室内方差）根据标准参考物质和生物测定条件（测试菌株和代谢活化）的不同，在16%至88%之间，而再现性（实验室间方差）则在33%至152%之间。实验室间变异性是主要的变异来源，占三个环境样品总变异的约55 - 95%。对照化合物诱变性效力的变异情况类似，1-硝基芘除外，其再现性在127%至132%之间。总之，NIST标准参考物质为一项关于复杂混合物的国际实验室间研究提供了有用的材料。通过确立这些物质诱变性结果的实验室内和实验室间方差，确定了这些标准参考物质作为沙门氏菌生物测定参考物质的有用性，识别了生物测定方案中的关键程序，并阐述了对未来工作的建议。
