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Key value for chemical safety assessment

Additional information

In vitro studies

 

Synthetic cryolite was negative in a gene mutation assay with Salmonella typhimurium tester strains TA1535, TA1537, TA98 and TA100 with and without S-9 mix obtained from Aroclor induced rat livers (Bayer AG, 1988). Doses ranging from 20 to 12,500 μg/plate were tested without toxic effects. The test was conducted in line with OECD guideline 471.

 

A well-conducted Rat Hepatocyte Primary Culture/DNA Repair Test is available (Pharmakon Research International, 1991a). The highest dose level evaluated in the study was 50 µg/ml as concentrations from 100 µg/ml induced cytotoxicity. Additional levels evaluated were 1, 5 and 10 µg/ml. None of the treated cultures produced mean NNG counts that were substantially greater than the solvent control and the % of cells in repair were less than 10%. Cryolite was considered negative in inducing unscheduled DNA repair in primary hepatocytes under the conditions of this assay. Based on this study, it can be assumed that cryolite does not induce gene mutations in mammalian cells in vitro.

 

Furthermore, a well-conducted (equivalent protocol compared to relevant OECD guideline) chromosome aberration study is available (Pharmakon Research International, 1991b). Initially, cryolite was evaluated for cytotoxicity in human lymphocyte cultures utilising cell proliferation kinetics and mitotic index (M.I.) as parameters. Cryolite was evaluated at concentrations of 1, 5, 25, 50, 75, 100, 175, 250, 500 and 1000 µg/ml with and without an exogenous metabolic activation system (S9 mix). Concurrent untreated and solvent (HPLC Grade Water) controls were also evaluated. Based on the cytogenetic findings, the concentrations selected for the chromosome aberration assay were 100, 500 and 1000 µg/ml. Human lymphocytes were exposed to three different phases of the cell cycle (G0/G1, 2 and S) after lymphocytic culture initiation. Each set of cultures was harvested at the appropriate scheduled time.

Results of the assay indicated no statistically significant increase in the proportion of aberrant metaphases or total aberrations/cell at any dose level or at any time interval evaluated.

 

In vivo studies

 

Inhalation exposure to 4.6 mg/m3 cryolite for 13 weeks was negative in a bone marrow chromosomal aberration test with male Crl:CD BR Sprague-Dawley rats; there was no effect on mitotic activity (Bayer AG, 1997a). This cytogenetic test was run within the 13-week study described in the section on repeated dose toxicity. Increased inorganic fluoride concentrations in urine, bones, and teeth were evident for rats in exposed to 4.6 mg/m3 cryolite in the 90 days inhalation toxicity study (see repeated dose toxicity) showing systemic exposure to cryolite.

Furthermore, in an in vivo bone marrow chromosomal aberration test, male and female Crl:CD BR Sprague-Dawley rats were exposed by snout-only inhalation to 2130 mg/m3cryolite for 6 hours (Huntingdon Life Sciences Ltd., 1997b / Bayer AG, 1997b). Results were negative for male and female animals. Bone marrow cells were sampled after recovery periods of 16, 24 and 48 hours. No clinical signs or mortalities were induced and there was no inhibition of mitotic activities of the target cells. All experimental parts were run in compliance with GLP and according to OECD guideline 475.


Short description of key information:
Cryolite does not induce gene mutations in a bacterial in vitro system. In vitro tests on induction of chromosomal aberrations (human lymphocytes) and unscheduled DNA synthesis (rat hepatocytes) are reported to be negative.
In vivo cryolite was negative in rat bone marrow chromosomal aberration tests after acute and repeated inhalation exposure.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the available data and in accordance with Directive 67/548/EEC and EU Classification, Labeling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008, classification is not necessary for mutagenicity.