Assessment of the toxicity of new chemicals is required by the EEC Directive 79/831, 6th amendment, and includes the determination of risks which could lead to cancer or to congenital malformation caused by genetic mutation.
The first level of screening consists in determining the genotoxicity of chemicals through a series of assays on micro-organisms and mammalian cells. Unfortunately, the results of these assays greatly depend upon how the methods are applied and upon the lines of bacterial strains used in performing the tests.
The objectives of the project are to prepare reference materials and to certify the mutagenic activity with a well defined, optimized procedure.
A first intercomparison on mutagenicity testing has been carried out without metabolic activation (-S9) and showed up serious difficulties in obtaining results with a good agreement. In order to prepare the 2nd intercomparison with metabolic activation (+S9) a preliminary study (with three labs) was started so as to investigate:
1) some of the most important parameters of variability of this test (-S9) like
- type of solvents, agar, glucose sterilization, inducer
- concentration of mutagen;
2) the appropriate S9-mix
- rat strain
- concentration of S9.
Part 1 of this study has been carried out. Results will be available by the end of May 1992.
Part 2 will be terminated by end of summer 1992. The analytical protocol for the 2nd intercomparison will be adopted according to the results of the preliminary study.
Two highly purified indirect mutagens (benzo(a)pyrene and 2-aminoanthracene) have been prepared as candidate reference materials. HPLC, GC-FID and GC-MS analysis indicated 99.2% purity of benzo(a)pyrene and 99.9% purity for 2-aminoanthracene. Homogeneity and stability studies (12 months) have been successfully completed.
Funding SchemeCSC - Cost-sharing contracts
SM5 4DS Carshalton
NW9 5HT London
EH33 2NE Tranent
YO1 5DD York