Zinc cyanide

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

no

GLP compliance:

yes

Type of assay:

mammalian erythrocyte micronucleus test

Test material

Test material information

Constituent 1

Reference substance name:

Zinc cyanide

EC Number:

209-162-9

EC Name:

Zinc cyanide

Cas Number:

557-21-1

Molecular formula:

Zn(CN)2

IUPAC Name:

ZINC DICYANIDE

Test material form:

solid: particulate/powder

Test animals

Species:

mouse

Strain:

Crj: CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

Animal number: Dose range-finding test: male and female, 18 animals / Main test: male, 33 animals
Age: 6 weeks / 7 weeks old
Quarantine and acclimatation: all animals examined for quarantine at the time of receipt and be acclimatized to housing condition. The healthy animals selected and used for the study based on general health conditions.
Identification : the animal labeled on tail with permanent marker pen and identification cards attached to each cage for an individual discrimination
Group assignment: after acclimation periods, animals weighted and randomly assigned according to body weight average and standard deviation.
ENVIRONMENTAL CONDITIONS
Temperature: 22 ± 3°C
Relative humidity: 50 ± 20 %
Air exchange: 10-20 times/h
Light cycle: light 12h / dark 12h
Illumination: 150-300 Lux
Animal per cage: more than 3 animals

Administration / exposure

Route of administration:

oral: gavage

Duration of treatment / exposure:

The test substance was administrated twice to starved animals for 3-4 hours by oral gavage (sonde), and positive control was administrated with a single intraperitoneal injection at the same time as final (2nd) administration day.

Frequency of treatment:

It was injected twice (24 hour interval). However, positive control was administered one time on the last administration day.

No. of animals per sex per dose:

Dose range-finding test 1: 3
Dose range-finding test 2: 3
Dose range-finding test 3: 3
Main test: 5

Positive control(s):

Name of the substance: Cyclophosphamide monohydrate (CPA)
Supplier: Sigma-Aldrich, Inc.
Purity: 99.9%

Examinations

Tissues and cell types examined:

Bone marrow cells

Evaluation criteria:

- Discrimination of polychromatic Erythrocytes: polychromatic erythrocytes are determined by appearence of orange-fluorescent light without nuclei.
- Discrimination of nonchromatic erythrocytes: nonchromatic erythrocytes are determined by appearence of only their black shadows without fluorescent light.
- Criteria of micronucleus: SIZE: from the smallest distinguishable one to the one as large as a half the diameter of erythrocytes. SHAPE: mainly round and includes the form of donut shape, half moon shape and so on. COLOR: same color with near cell nucleus; green fluorescent in acridine orange.

Statistics:

The following statistic analyses were done using a SPSS program (ver. 19.). The result of the statistical evaluation was regarded significantly when the P value was less than 0.5.

Results and discussion

Test results

Key result

Sex:

male/female

Genotoxicity:

negative

Toxicity:

no effects

Negative controls validity:

valid

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

Under the experimental conditions, the results showed that there was no increase of MNPCE at any dose of the test substance compared to the negative control group, and also statistical significance was not observed. In addition, no statistical significance was observed in the value for the ratio of PCE to total erythrocytes between the test substance-dosed group and negative control group.
Therefore, the test substance, Zinc cyanide, was determined not to indice an increased frequency micronuclei in the bone marrow cells of male ICR mice under the present experimental condition.

Executive summary:

For that endpoint, one reliable study to assess in vivo genotoxicity on the registered substance on mammalian erythrocyte was available. The study was performed according to the OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test).

Under the experimental conditions, the registered substance " Zinc cyanide batch n°10185145" does not increase MNPCE at any doses tested compared to the negative control group. In addition, no statistical significance was observed in the value for the ratio of PCE to total erythrocytes between the test substance-dosed group and negative control group. Therefore, the registered substance " Zinc cyanide batch n°10185145" was determined not to induce an increased frequency micronuclei in the bone marrow cells of male ICR mice under these experimental conditions.

The validity criteria were successful and the study was therefore regarded as acceptable for that endpoint.