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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian germ cell study: cytogenicity / chromosome aberration
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
Not applicable
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Documentation insufficient for assessment
Justification for data waiving:
other:
Cross-referenceopen allclose all
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
reference to other study

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1979

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Animals were exposed to the test material through diet and were sacrificed at one month after treatment. Prior to sacrifice, animals were treated with a metaphase-arresting agent (e.g., colchicines). Bone marrow cell smears were then prepared and stained, and metaphase cells were analysed for chromosomal aberrations.
GLP compliance:
not specified
Type of assay:
chromosome aberration assay

Test material

Constituent 1
Reference substance name:
Zinc chloride
EC Number:
231-592-0
EC Name:
Zinc chloride
Cas Number:
7646-85-7
IUPAC Name:
zinc dichloride
Details on test material:
Not reported

Test animals

Species:
mouse
Strain:
C57BL
Sex:
male
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Age at study initiation: 8 wk
- Weight at study initiation: 25 g
- Housing: No data
- Diet (e.g. ad libitum): Standard diet (1.1 % calcium)


Administration / exposure

Route of administration:
oral: feed
Vehicle:
- Vehicle(s)/solvent(s) used: None
Details on exposure:
DIET PREPARATION
- Mixing appropriate amounts with (Type of food): Standard diet (with 1.1 % calcium) and low-calcium (0.03 %) diet mixed with zinc chloride (0.5 % Zn)
Duration of treatment / exposure:
One month
Frequency of treatment:
Daily ad libitum through diet for one month
Post exposure period:
Not applicable
Doses / concentrations
Remarks:
Doses / Concentrations:
0.5 % Zn
Basis:
nominal in diet
No. of animals per sex per dose:
25 animals per group, 10 animals evaluated at the end of the treament
Control animals:
yes, plain diet
other: low-calcium diet
Positive control(s):
Not reported

Examinations

Tissues and cell types examined:
Metaphase bone-marrow cells
Details of tissue and slide preparation:
DETAILS OF SLIDE PREPARATION: Metaphase bone marrow cells were prepared by injecting 0.4 mL/30 g bw of 0.025 % colchicine solution, 1 h before sacrifice, followed by washing of the femur shafts with 2.2 % sodium citrate solution. The cells were centrifuged, kept in hypotonic (1 %) sodium citrate solution for 12 min, centrifuged again and fixed in ethanol: acetic acid (3: 1). Few drops of final cell suspension were spread on a clean glass slide and stained with lacto-orcein.


METHOD OF ANALYSIS: 50 well-spread metaphase cells from each animal (a total of 500 from each group) were analysed for structural chromosomal aberrations

OTHER: Calcium was determined in quadruplicate in blood serum by a fluoromet ric procedure
Evaluation criteria:
Not reported
Statistics:
Chromosomal data were evaluated using chi-square analysis, and the weight and calcium data were tested by an analysis of variance.

Results and discussion

Test results
Sex:
male
Genotoxicity:
positive
Toxicity:
yes
Vehicle controls validity:
valid
Negative controls validity:
not applicable
Positive controls validity:
not applicable
Additional information on results:
Body weights of mice were significantly reduced on treatment with test material and low-calcium diet respectively. However, the effect was more pronounced with a combined treatment of test material and low-calcium diet.

Serum calcium was reduced in animals on a low-calcium diet, and this effect was accentuated by intoxication with test material whereas this intoxication as such did not significantly influence calcium levels in animals on the standard diet.

The number of dicentrics as well as the number of cells carrying structural aberrations was significantly increased in mice kept on a low-calcium diet plus test material.

Any other information on results incl. tables

Table 1: Chromosome analysis of mice treated with test material in a diet containing normal or low calcium

Treatment and diet       Body weight Serum calcium Cells with structural aberrations         Type and number of structural aberrations                     
 Chromatid aberrations        Chromosomal aberrations            
 Gaps  Breaks  Exchange  Gaps  Fragments  Despiralisations Translocations  Dicentrics
 Control (only standard diet) 29.90 ± 0.12 10.24 ± 0.06 1.80 ± 0.60 1.20 ± 0.49  -  - 0.60 ± 0.35  -  -  -
 Control (low calcium diet) 21.80 ± 0.27** 9.45 ± 0.15** 2.00 ± 0.63 1.80 ± 0.60  -  - 0.40 ± 0.28  -  -  -
Standard diet + Zinc chloride (0.5 % Zn) 17.90 ± 0.23## 9.76 ± 0.29 2.80 ± 0.75 1.80 ± 0.60 1.20 ± 0.20   -  - 0.40 ± 0.28  -  -  0.40 ± 0.28
Low calcium diet + Zinc chloride (0.5 % Zn) 12.05 ± 0.25##** 8.76 ± 0.24#* 5.00 ± 1.00## 3.20 ± 0.80  -  - 0.40 ± 0.28 0.60 ± 0.35  -  - 1.20 ± 0.49#

# and ## indicates statistically significant differences from the respective controls without test material in the diet at p < 0.05 and p < 0.01 levels

* and ** indicates statistically significant differences from the respective treated group with calcium in the diet (standard diet) at p < 0.05 and p < 0.01 levels .

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): positive
The test material caused severe chromosomal anomalies, particularly in animals kept on a low calcium diet under the conditions of the test.
Executive summary:

A study was conducted to determine the chromosomal aberration inducing capacity of the test material using mice bone marrow cells. No guideline or GLP compliance was documented in the study report.

C57BI male mice were exposed to test material orally daily through standard and low-calcium diet for one month. The metaphase bone marrow cells were obtained, exposed to hypotonic solution and fixed. The cells were then spread on slides and stained using lacto-orcein. 50 well-spread metaphase cells from each animal (a total of 500 from each group) were analysed for chromosomal aberrations and the results were evaluated using chi-square method.

Body weights of mice were significantly reduced on treatment with the test material in standard diet as well as low-calcium diet alone. However, the effect was more pronounced with a combined treatment of test material and low calcium diet. Serum calcium was reduced in animals on a low calcium diet and this effect was accentuated to 9.76 ± 0.29, by intoxication with the test material whereas this intoxication as such did not significantly influence calcium levels in animals on a normal diet.

The number of dicentrics as well as the number of cells carrying structural aberrations was significantly increased in mice kept on a low calcium diet plus test material.

The test material caused severe chromosomal anomalies, particularly in animals kept on a low calcium diet under the conditions of the test.

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