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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1988-10-14 to 1988-12-12
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
GLP guideline study with acceptable restrictions Both the negative and positive control data appear to be high in comparison with up to date control data from other testing laboratories. No target organ toxicity by a change of the PCE/NCE ratio could be observed in any of the treatment groups. The fluctuation of the re-scoring results for one male animal showing significant increase in MN-PCE frequency might be indicative for less experienced staff scoring the cells.
Justification for type of information:
Dissociation of SnSO_4 into Sn^2+ and SO_4^2-. Read across to SnMSA. No adverse effects of the different anions in higher concentrations than used known. So Sn(II) is responsible for effects.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report Date:
1989

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Version / remarks:
adopted 1983-05-26
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
other: crystalline powder
Details on test material:
- Name of test material (as cited in study report): STANNOUS METHANE SULPHONATE (12.11.87)(supplied by Toxicol Laboratories Limited)
- Physical state: off white-coloured crystalline powder
- Storage condition of test material: plastic flip-top jar, below -20°C in the dark

Test animals

Species:
mouse
Strain:
other: CFLP
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Interfauna (UK) Limited, Wyton, Huntingdon, Cambridgeshire
- Age at study initiation (males and females): approximately five to eight weeks old
- Weight at study initiation (males and females): 22 - 28 g
- Assigned to test groups randomly: yes
- Fasting period: 3 -4 hours fast immediately before dosing and for approximately two hours after dosing
- Housing: housed in groups of up to five by sex in solid-floor polypropylene cages with sawdust bedding
- Diet (ad libitum, except during fasting period): rat and Mouse Expanded Diet No. 1 (Special Diet Services Limited, Witham Essex, U.K.)
- Water (ad libitum, except during fasting period): mains drinking water
- Acclimation period: minimum period of five days

ENVIRONMENTAL CONDITIONS
- Temperature: 19 - 21 °C
- Relative humidity: 50 - 58%
- Air exchanges: approximately 15 changes/hour
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
- Vehicle(s)/solvent(s) used: distilled water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
Test material was freshly prepared as a solution at the appropriate concentration in the vehicle after grinding to a fine powder using a mortar and pestle.
Duration of treatment / exposure:
one treatment only
Frequency of treatment:
once
Doses / concentrations
Remarks:
Doses / Concentrations:
1000 mg/kg
Basis:
actual ingested
No. of animals per sex per dose:
treatment group: 5 males / 5 females (total: three groups)
vehicle control group: 5 males / 5 females (total: three groups)
positive control group: 5 males / 5 females (total: one group)
Control animals:
yes, concurrent vehicle
Positive control(s):
cyclophosphamide
- Doses / concentrations: 50 mg/kg

Examinations

Tissues and cell types examined:
Stained bone marrow smears were examined at random using light microscopy at x 1000 magnification. The incidence of micronucleated cells per 1000 polychromatic erythrocytes PCE per animal was scored. In addition, the number of normochromatic erythrocytes NCE associated with 1000 polychromatic erythrocytes was counted; these cells were also scored for incidence of micronuclei.
The ratio of normochromatic to polychromatic erythrocytes was calculated together with appropriate group mean values for males and females separately and combined.
Details of tissue and slide preparation:
RANGE-FINDING TOXICITY STUDY:
A range-finding study was performed. Groups of mice (2 males / 2 females) were dosed with stannous methane sulphonate (12.11.87) as follows: 500, 1000, 2000, and 5000 mg/kg.
All animals were dosed once only at the appropriate dose level by gavage. The volume administered to each animal was calculated according to its fasted bodyweight at the time of dosing.
Animals were observed 1 and 4 hours after dosing and subsequently once daily for 3 days. Deaths and evidence of overt toxicity were recorded at each observation. No necropsies were performed. At 72-hours after dosing, up to 2 mice of each sex were sampled for bone-marrow cells to evaluate any specific bone-marrow toxicity in the absence of deaths.

TREATMENT AND SAMPLING TIMES:
Three groups, each of five males and five female mice were dosed once only with test material at the "maximum tolerated dose level". One group of mice was killed by cervical dislocation 24 hours following treatment, a second at 48 hours and a third at 72 hours. In addition, three groups (5 males / 5 females each) were treated with the vehicle alone and one group (5 males / 5 females) was treated with the positive control. The vehicle control groups were killed 24, 48 and 72 hours following treatment and positive control group animals were killed 24 hours following treatment.

DETAILS OF SLIDE PREPARATION:
Immediately following sacrifice, one femur was dissected from each animal, aspirated with foetal calf serum and bone marrow smears prepared following centrifugation and re-suspension. The smears were air-dried, fixed in absolute methanol, and stained in May-Grünwald/Giemsa.

OTHER:
All animals were observed for signs of overt toxicity and death 1 and 4 hours after dosing and then once daily as applicable.
Evaluation criteria:
A comparison was made between the number of micronucleated polychromatic erythrocytes occurring in each of the three test material groups and the number occurring in the corresponding vehicle control groups.
A positive mutagenic response is demonstrated when a statistically significant increase in the number of micronucleated polychromatic erythrocytes is observed for either the 24, 48 or 72 hour kill times.
If the above criteria are not demonstrated, then the test material is considered to be non-mutagenic under the conditions of the test.
A positive response for bone marrow toxicity is demonstrated when the treatment group mean normochromatic to polychromatic ratio is twice the vehicle control value or when a treatment related increase is shown to be statistically significant.
Statistics:
If necessary, and where possible, all data were statistically analysed using the Mann-Whitney U-Test.

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Remarks:
please refer to the field "Additional information on results" below
Toxicity:
yes
Remarks:
please refer to the field "Additional information on results" below
Vehicle controls validity:
not specified
Negative controls validity:
not examined
Positive controls validity:
not specified
Additional information on results:
RESULTS OF RANGE-FINDING TOXICITY STUDY
- 5000 mg/kg dose level: all four animals showed adverse clinical symptoms which included: hunched posture, lethargy, pilo-erection, decreased respiratory rate and ptosis. Three of these four animals subsequently died on the first day post treatment while the fourth animal, a male, survived for the full period of the test showing fewer clinical signs on successive days.
- 2000 mg/kg dose level: the four animals showed similar clinical symptoms to those treated with 5000 mg/kg. Two of the four animals died, one on day 0 and the other on day two.
- 500 and 1000 mg/kg dose levels: all animals exhibited hunched posture, lethargy, pilo-erection and decreased respiratory rate one hour after dosing. At four hours post dosing the respiration rate was back to normal and on days 1, 2 and 3 post dosing no clinical symptoms were observed. No evidence of excessive bone marrow toxicity was observed.
The 1000 mg/kg dose level was selected as the maximum tolerated dose used for the micronucleus study.

RESULTS OF DEFINITIVE STUDY
- mortality and clinical observations: one of the animals in the 48-hour treatment group died on the day of dosing. The clinical symptoms observed were similar to those seen in the toxicity range-finding study, although occasionally animals showed additional symptoms of ataxia and body tremors.

- there were no significant increases in the frequency of micronucleated PCE's in any of the treatment groups.
- one male in the 24-hour treatment group had a frequency of 13 micronucleated PCE#s per 1000 PCE's. The slide from this animal was rescored independently 3 times and gave scores of 6, 9 and 8 micronucleated PCE's per 1000 PCE's . According to the authors, it may be concluded that this animal did have a higher than normal frequency of micronucleated PCE's although it was probably not treatment-related.
- there were no significant increases in the frequency of micronucleated NCE's in the treatment groups and also there was no significant changes in the NCE/PCE ratio.
- positive control group: a marked increase in the incidence of micronucleated polychromatic erythrocytes was observed.

- the test material did not induce a statistically significant increase in micronucleated PCE'S. Stannous methane sulphonate (12.11.87) was considered therefore to be non-mutagenic under the conditions of the test.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
Stannous methane sulphonate was found not to produce micronuclei in polychromatic erythrocytes of mice under the conditions of the test.