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Diss Factsheets

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study is considered as reliable with restrictions since the study is conducted for the read-across substance, sodium hypochlorite. However, the data presented in the publication are sufficient and scientifically acceptable. Read-across justification: The target substance is a reaction mass from blending of two components (bentzotriazole solid and 25 % tetramethylammonium hydroxide water solution) followed by reaction with chlorine gas. The main constituent of this multi-constituent are tetramethylammonium hypochlorite and tetramethylammonium chloride. Based on the chemical structure and chemical reactions of chlorine compounds the target substance and the source substances (chlorinated bleaching agents such as sodium hypochlorite) meet the same toxicological behaviour in the physiological conditions. Their irritation and skin sensitisation as well as acute and long-term adverse effects to human health are similar. Therefore, and in order to avoid the unnecessary animal testing, the read-across data from sodium hypochlorite and chlorine is used to evaluate the toxicokinetics, the genetic toxicity, the sensitisation potential of the target substance.

Data source

Reference
Reference Type:
publication
Title:
Micronucleus Test in Mice on 39 Food Additives and Eight Miscellaneous Chemicals.
Author:
Hayashi et al
Year:
1988
Bibliographic source:
Fd. Chem. Toxic. Vol. 26, No. 6, pp. 487-500.

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
no
GLP compliance:
not specified
Type of assay:
micronucleus assay

Test material

Constituent 1
Reference substance name:
Sodium hypochlorite
EC Number:
231-668-3
EC Name:
Sodium hypochlorite
Cas Number:
7681-52-9
IUPAC Name:
sodium hypochlorite
Details on test material:
- Name of test material (as cited in study report): sodium hypochlorite
- Composition of test material, percentage of components: 6.6 % as available Cl

Test animals

Species:
mouse
Strain:
other: ddY
Sex:
male
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Shizuoka Agricultural Cooperative Association for Laboratory Animals, Shizuoka, Japan
- Age at study initiation: 8 week old
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum

Administration / exposure

Route of administration:
intraperitoneal
Vehicle:
- Vehicle(s)/solvent(s) used: saline
Details on exposure:
Number of doses: 1 (0, 312.5, 625, 1250, 2500 mg/kg)
4 (300 mg/kg)
Duration of treatment / exposure:
single injection
Frequency of treatment:
Time between doses 24 hours (300mg/kg)
Post exposure period:
24 hours
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0, 312.5, 625, 1250, 2500 mg/kg
Basis:
nominal conc.
one dose
Remarks:
Doses / Concentrations:
300 mg/kg
Basis:
nominal conc.
four doses
No. of animals per sex per dose:
6
Control animals:
yes, concurrent vehicle
Positive control(s):
mitomycin C

Examinations

Tissues and cell types examined:
Mortality was observed during study. Bone marrow cells were collected and analyzed.
Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION:
The maximum dose were selected based on pilot experiment.

TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields):
The sampling time after the administration was 24 hours.

DETAILS OF SLIDE PREPARATION:
Femoral bone marrow cells were flushed out with foetal bovine serum and smeared on clean glass slides. Cells were fixed with methanol for 5 min, and stained with Acridine orange for the pilot experiment and with Giemsa for the full scale test.

METHOD OF ANALYSIS:
One thousand polychromatic erythrocytes per mouse were scored using a light microscope with a high power objective (x100), and the number of micronucleated polychromatic erythrocytes (MNCPEs) was recorded. The proportion of polychromatic erythrocytes (PCEs) among the total erythrocytes was also evaluated by observing 1000 erythrocytes on the same slide.

OTHER:

Results and discussion

Test results
Sex:
male
Genotoxicity:
negative
Toxicity:
yes
Remarks:
Mortality (6/6) observed at highest concentration tested (2500 mg/kg)
Vehicle controls validity:
not applicable
Negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
RESULTS OF DEFINITIVE STUDY
- Induction of micronuclei (for Micronucleus assay): No
- Ratio of PCE/NCE (for Micronucleus assay): see table below

Any other information on results incl. tables

Results of the micronucleus test with sodium hypochlorite in mice

Dose

MNPCE [%]

PCE [%]

Mortalities

0

0.17 ± 0.16

56.7 ± 14.8

0/6

312.5

0.20 ± 0.09

61.3 ± 3.8

0/6

625

0.22 ± 0.20

56.2 ± 9.8

0/6

1250

0.17 ± 0.08

29.3 ± 11.8

0/6

2500

-a

-

6/6

positive controlb

3.77 ± 1.08

47.7 ± 18.9

0/6

300c

0.17 ± 0.12

47.3 ± 9.8

0/6

MNPCE              micronucleated polychromatic erythrocytes

PCE                     polychromatic erythrocytes

a                           Not evaluated due to mortalities

b                           2.0 mg/kg bw Mitomycin C

c                           4 doses of 300 mg/kg bw each, 24 hours spacing

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
Read-across substance, sodium hypochlorite, was tested in mouse bone marrow micronucleus test. The test substance did not induce micronuclei in the bone marrow erythrocytes in mice.
Executive summary:

Six male mice of eight weeks old were intraperitoneally administered a single dose of sodium hypochlorite at concentrations of 0, 312.5, 625, 1250, 2500 mg/kg bw. In a second trial 4 doses of 300 mg/kg bw spaced by 24 hours were similarly administered. Femoral bone marrow cells were flushed out with foetal bovine serum and smeared on clean glass slides. Cells were fixed with methanol for 5 min, and stained with Acridine orange for the pilot experiment and with Giemsa for the full scale test. One thousand polychromatic erythrocytes per mouse were scored using a light microscope with a high power objective (x100), and the number of micronucleated polychromatic erythrocytes (MNCPEs) was recorded. The proportion of polychromatic erythrocytes (PCEs) among the total erythrocytes was also evaluated by observing 1000 erythrocytes on the same slide.

Based on this study no signs of genotoxicity was observed.