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Overview, conclusions, and recommendations of the IPCS collaborative study on complex mixtures.
L D Claxton1, G Douglas, D Krewski
1Health Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711.
Mutation Research
|January 1, 1992
Summary
This study assessed variability in extracting and bioassaying environmental samples using the Salmonella assay. NIST standard reference materials proved valuable for inter-laboratory studies, establishing their utility for mutagenicity testing.
Area of Science:
- Environmental Science
- Toxicology
- Analytical Chemistry
Background:
- Complex environmental mixtures require reliable reference materials for accurate bioassay.
- Standard Reference Materials (SRMs) from NIST are crucial for inter-laboratory comparisons.
- The International Programme on Chemical Safety (IPCS) coordinated this collaborative study.
Purpose of the Study:
- To examine variability in extraction and bioassay of NIST SRMs.
- To evaluate the feasibility of establishing bioassay reference values for SRMs.
- To estimate intra- and inter-laboratory variability in mutagenic potencies.
Main Methods:
- International collaborative study involving 20 laboratories.
- Extraction and bioassay of two particulate environmental samples (SRMs).
- Salmonella/microsomal plate incorporation assay for mutagenicity testing.
- Bioassay of polycyclic aromatic hydrocarbon (PAH) solution and control compounds.
Main Results:
- Repeatability (intra-laboratory variance) ranged from 16% to 88%.
- Reproducibility (inter-laboratory variance) ranged from 33% to 152%.
- Between-laboratory variability accounted for 55-95% of total variation in environmental samples.
Conclusions:
- NIST SRMs are useful for international inter-laboratory studies of complex mixtures.
- The study established the utility of NIST SRMs as reference materials for the Salmonella bioassay.
- Critical bioassay procedures were identified, with recommendations for future efforts.