Zinc bromide

Genetic toxicity: in vivo

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-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

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

Test material information

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.