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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:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to OECD and EC test guidelines, and in compliance with GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1988
Report Date:
1988

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.12 (Mutagenicity - In Vivo Mammalian Erythrocyte Micronucleus Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Unifoam AZ SO-NL
- Substance type: yellow powder
- Physical state: solid
- Analytical purity: 100%
- Lot/batch No.: 23.3.88/4
- Storage condition of test material: room temperature in the dark
- Other: suspensions of unifoam az so-nl were prepared in 1% methylcellulose using a Silverson high-speed mixer, and prepared on the morning of the test at the concentrations shown overleaf.

Test animals

Species:
mouse
Strain:
CD-1
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source:Charles River U.K. Limited, Margate, Kent, England
- Age at study initiation:35 days old
- Weight at study initiation:22 and 24 grams
- Assigned to test groups randomly: yes
- Fasting period before study: The animals were deprvied of diet overnight prior to and for two hours after oral dosing.
- Housing:Each group of 2 or 5 mice was kept in a plastic disposable cage
- Diet (e.g. ad libitum):free access to pelleted Labsure LAD 1 rodent breeding diet.
- Water (e.g. ad libitum):free access to tap water.
- Acclimation period:4 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C):22
- Humidity (%):no data
- Air changes (per hr):30
- Photoperiod (hrs dark / hrs light):12/12

IN-LIFE DATES: From: To: no data

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
1% methylcellulose
Details on exposure:
Preliminary toxicity test:
Increasing dosages of Unifoam AZ SO-NL were administered up to a maximum of 5000 mg/kg bodyweight (0, 312.5, 625, 1250, 2500, 5000mg/kg). Twelve male and twelve female mice were used in this experiment (2mice/sex/group).
Following dosing, the animals were observed regularly during the working day for a period of 72 hours, and any mortalities or signs of malreaction during the experiment were recorded.
Duration of treatment / exposure:
single treatment
Frequency of treatment:
single treatment
Post exposure period:
24, 48, and 72 hours for Unifoam AZ SO-NL treated groups
24 hours for positive control group (Mitomycin C)
Doses / concentrations
Remarks:
Doses / Concentrations:
5000mg/kg
Basis:
actual ingested
No. of animals per sex per dose:
Vehicle comtrol group: 15 males and 15 females
Unifoam AZ SO-NL group: 19 males and 17 females
Mitomycin C positive control group: 5 males and 5 females
Control animals:
yes
Positive control(s):
Mitomycin C, obtained from Sigma London Chemical Company Limited (batch number 96F-0547-1) was tested at 12mg/kg.
It was prepared as a solution in sterile 0.9% saline at a concentration of 0.6 mg/ml.

Examinations

Tissues and cell types examined:
Micronucleated cells
Details of tissue and slide preparation:
Following dosing, the animals were examined daily and weighted prior to dosing, and any mortalities or clinical signs of reaction to the test compounds were recorded. Five males and five females from the negative control and test compound groups were sacrificed 24, 48, and 72 hours after dosing. The positive control group was sacfrificed 24 hours after dosing. The animals were killed by cervical dislocation and both femurs dissected out from each animal. The femurs were cleared of tissue and one epiphysis removed from each bone.

A direct bone marrow smear was made onto a slide containing a drop of calf serum. One smear was made from each femur. The prepared smears were air-dried and stained for 10 minutes in 10% Giemsa. Following rinsing and differentiation in buffered distilled water for 10 minutes, the smears were air-dried and mounted with coverslips using DPX.

Stained smears were examined by light microscopy to determine the incidence of micronucleated cells per 1000 polychromatic erythrocytes per animal. The ratio of polychromatic to normochromatic erythrocytes for each animal was assessed by examination of at least 1000 erythrocytes. A record of the number of micronucleated normochromatic erythrocytes was also kept.

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
no effects
Remarks:
but limit comcentration tested
Vehicle controls validity:
valid
Negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
RESULTS OF RANGE-FINDING STUDY
- Dose range: 0-5000mg/kg
- Solubility: no data
- Clinical signs of toxicity in test animals:hunched posture and piloerection in the high dose groups until 4 hours after dosing

RESULTS OF DEFINITIVE STUDY
- Induction of micronuclei (for Micronucleus assay):Unifoam AZ SO-NL did not cause any statistically significant increases in the number of micronucleated polychromatic erythrocytes at any of the three kill times - (P>0.05 using Wilcoxon's sum of ranks test. Unifoam AZ SO-NL did not cause any substantial increases in the incidence of micronucleated normochromatic erythrocytes at any of the three kill times.
Mitomycin C caused large, highly significant increases (P<0.001) in the frequency of micronucleated polychromatic erythrocytes.
- Ratio of PCE/NCE (for Micronucleus assay):Unifoam AZ SO-NL failed to cause any significant decreases in the ratio of polychromatic to normochromatic erythrocytes (P>0.05 using Wilcoxon's sum of ranks test). Mitomycin C caused statistically significant decreases in the ratio (P<0.05).

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
Executive summary:

In this assessment of the effect of Unifoam AZ SO-NL on the incidence of micronucleated polychromatic erythrocytes in mice, a dosage of 5000 mg/kg bodyweight was administered orally, by intragastric gavage (HLS 1988, OCI79/88802). (A preliminary toxicity test had been carried out to determine the toxicity of Unifoam AZ SO-NL). As no toxicity was, observed at a dose level of 5000 mg/kg, the highest dose recommended for acute toxicity tests, this dosage was chosen for the main test.

Negative and positive control groups were dosed in an identical manner, orally by intragastric gavage. The negative control group received the vehicle, 1% methylcellulose. The positive control group was treated with mitomycin C, at 12 mg/kg.

Bone marrow smears were obtained from the negative control and test compound groups at 3 sampling times; these being 24, 48 or 72 hours after dosing. Bone marrow smears were obtained from the positive control group 24 hours after dosing. One smear from each animal was examined for the presence of micronuclei in 1000 polychromatic erythrocytes. The ratio of polychromatic to normochromatic erythrocytes was assessed by examination of at least 1000 erythrocytes from each animal. A record of the incidence of micronucleated normochromatic erythrocytes was also kept.

 

At all sampling times, mice treated with Unifoam AZ SO-NL showed no significant increase in the frequency of micronucleated polychromatic erythrocytes.

There was no significant decrease in the ratio of polychromatic to normochromatic erythrocytes after treatment of the animals with Unifoam AZ SO-NL.

The positive control compound, mitomycin C, produced large, highly significant increases in the frequency of micronucleated polychromatic erythrocytes together with decreases in the ratio of polychromatic to normochromatic erythrocytes.

It is concluded from the results obtained that Unifoam AZ SO-NL shows no evidence of mutagenic potential or bone marrow cell toxicity when administered orally in this in vivo test procedure.