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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1999-05-05 to 1999-06-21
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP-Guideline study. According to the ECHA guidance document "Practical guide 6: How to report read-across and categories (March 2010)", the reliability was changed from RL1 to RL2.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report date:
2000

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
GLP compliance:
yes
Type of assay:
in vitro mammalian chromosome aberration test

Test material

Constituent 1
Reference substance name:
Automatically generated during migration to IUCLID 6, no data available
IUPAC Name:
Automatically generated during migration to IUCLID 6, no data available
Details on test material:
- Name of test material (as cited in study report): Zeostop X (silver alumino-silikate)
- Chemical name: Zeolite, cuboidal, crystalline, synthetic, non-fibrous
- Framework: cuboidal
- Related CAS number: 1318-02-1
- Analytical purity: approx. 100%
- Lot/batch No.: MR 453 136
- Physical state: white powder
- Composition of test material, percentage of components (surface modified with Ag): Si/Al molarity 1.24
Al2O3: 25.6%
CaO 0.08%
Fe2O3 0.00%
K2O 00.08%
MgO 00.00%
Na2O 11.71%
SiO2 37.33%
Ag2O 02.80%
loss resulting from combustion (900°C)
- Expiry date: May 2000
- Storage: in dark and at room temperature

Method

Species / strain
Species / strain / cell type:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Metabolic activation system:
liver post-mitochondrial fraction from rats, induced with Aroclor 1254 (S-9)
Test concentrations with justification for top dose:
between 27.5 and 72.5 µg/mL without S-9, and between 164 and 400 µg/mL with S-9
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
no
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 4-Nitroquinoline-1-oxide and cyclophosphamide
Details on test system and experimental conditions:
Culture medium: McCoy´s 5A medium

In Experiment 1, treatment in the absence and presence of S-9 was for 3 hours followed by a 17 hour recovery period prior to harvest (3+l7). The S-9 used was prepared from a rat liver post-mitochondrial fraction (S-9) from Aroclor 1254-induced animals. The test article dose levels for chromosome analysis were selected by evaluating the effect of Zeostop X on cell numbers. Chromosome aberrations were analysed at three consecutive dose levels. The highest concentrations chosen for evaluation, 67.11 and 400 µg/mL, induced approximately 48% and 63% reduction in cell number in the absence and presence of S-9 respectively.

In Experiment 2, treatment in the absence of S-9 was continuous for 20 hours. Treatment in the presence of S-9 (using S-9 prepared from animals induced with phenobarbitone and beta-naphthoflavone) was for 3 hours only followed by a 17 hour recovery period prior to harvest (3+17). Chromosome aberrations were analysed at three consecutive dose levels. The highest concentrations chosen for analysis were, 72.54 and 313.2 µg/mL, which induced approximately 54% and 49% reduction in cell number in the absence and presence of S-9, respectively.

Appropriate negative control cultures were included in the test system in both experiments under each treatment condition. 4-Nitroquinoline-1-oxide and cyclophosphamide were employed as positive control chemicals in the absence and presence of S-9, respectively.
Evaluation criteria:
Cells were harvested, fixed and transferred to microscope slides. After the slides had dried the cells were stained with Giemsa. Chromosome analysis was performed microscopically.

Results and discussion

Test results
Species / strain:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
without S-9: at 67.1 µg/ml (exp 1) and 72.5 µg/ml (exp 2) ; with S-9: at 400 µg/l (exp 1) and 313.2 µg/l (exp 2)
Vehicle controls validity:
not examined
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
The test article was poorly soluble and undissolved material was observed at all concentrations.
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

The proportion of cells with structural aberrations in the negative control cultures fell within historical solvent control ranges. Cells receiving 4-Nitroquinoline-1-oxide and cyclophosphamide both induced statistically significant increases in the proportion of cells with structural aberrations.

Treatment of cells with Zeostop X in the absence and presence of S-9 resulted in increased frequencies of cells with aberrations. Frequencies which exceeded historical negative control ranges in both replicates and where the total number of aberrant cells was significantly higher than the concurrent negative control were observed at either the high or intermediate concentration analysed from all treatment regimes. The total number of aberrations seen was clearly elevated in most treated cultures and exchanges, which are observed only infrequently in negative controls, were induced.

Experiment 1 (3+17) without S-9 mix (200 cells were scored each):
µg/mL
   cells...with aberrations          with aberrations
                               including gaps                     excluding gaps
-----------------------------------------------------------
solvent
                  0                                             0
27.49
                      4                                             3
42.95
                      7                                             6
67.11
                      26                                           17
pos.
                        30                                           27
Reduction in cell number with increasing concentration 0% (solvent), 27.49%, 20%, 48%; value for positive control not given

Experiment 1 (3+17) with S-9 mix:
µg/mL
   cells...with aberrations          with aberrations
                               including gaps                     excluding gaps
-----------------------------------------------------------
solvent
                  1                                             1
163.8
                      5                                             2
320
                         3                                             2
400
                         27                                           20
pos.
                        102                                         101
Reduction in cell number with increasing concentration 0% (solvent), 8%, 29%, 63%; value for positive control not given

Experiment 2 (20+0) without S-9 mix:
µg/mL
   cells...with aberrations          with aberrations
                               including gaps                     excluding gaps
-----------------------------------------------------------
solvent
                  6                                             4
37.87
                      5                                             1
61.66
                      33                                           23
72.54
                      14                                           10
pos.
                        51                                           40
Reduction in cell number with increasing concentration 0% (solvent), 26%, 59%, 54%; value for positive control not given


Experiment 2 (3+17) with S-9 mix:
µg/mL
   cells...with aberrations          with aberrations
                               including gaps                     excluding gaps
-----------------------------------------------------------
solvent
                  7                                             4
226.3
                      10                                           6
266.2
                      18                                           15
313.2
                      22                                           14
pos.
                        187                                         186
Reduction in cell number with increasing concentration 0% (solvent), 19%, 42%, 49%; value for positive control not given

Increased frequencies of cells with numerical aberrations which exceeded historical negative control ranges were observed under all treatment conditions. The effect was attributable to endoreduplication. It should be noted that the biological significance of endoreduplication and its likely occurrence in vivo is not clear.

Numerical aberrations observed:

Experiment 1 (3+17) without S-9 mix
µg/mL
   cells
      counted                          H             E             P
-----------------------------------------------------------
solvent
  206                          1              0              5
27.49
       204                         0              0              4
42.95
       213                         1              5              7
67.11
       260                         1              52            7
pos.
        210                         3              0              7


Experiment 1 (3+17) with S-9 mix:
µg/mL
   cells
      counted                          H             E             P
-----------------------------------------------------------
solvent
  205                         0              1              4
163.8
       210                         2              0              8
320
          243                         0              35            8
400
          264                         0              58            6
pos.
        202                          0              0              2


Experiment 2 (20+0) without S-9 mix:
µg/mL
   cells
      counted                          H             E             P
-----------------------------------------------------------
solvent
  211                          2              0              9
37.87
       210                         1              5              4
61.66
       274                          0              65            9
72.54
       263                          0              59            4
pos.
        207           3              0              4 


Experiment 2 (3+17) with S-9 mix:
µg/mL
   cells
      counted                          H             E             P
-----------------------------------------------------------
solvent
  208                         2              0              6
226.3
       212                         0              10            2
266.2
       229                         1              25            3
313.2
       284                         0              81            3
pos.
        203                         0              0              3 

endoreduplication (E)
polyploid (P)
hyperdiploid (H)

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
positive

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