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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
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998
Report Date:
1998

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Version / remarks:
12/96 final draft
Deviations:
no
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
mouse
Strain:
other: Crl: CD-1 (ICR) BR
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Labs Raleigh NC
- Age at study initiation: approx 8 weeks
- Weight at study initiation: 30.6 - 33.9 g (males); 23.6-28.4 g (females)
- Assigned to test groups randomly: yes
- Fasting period before study: no
- Housing: 5 animals per polycarbonate cage
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-26
- Humidity (%): 30-70
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
- Vehicle(s)/solvent(s) used: water
- Amount of vehicle (if gavage or dermal): 10 ml/kg bw
Duration of treatment / exposure:
2 days
Frequency of treatment:
24, 48h
Doses / concentrations
Dose / conc.:
2 000 mg/kg bw/day (nominal)
No. of animals per sex per dose:
Range finding experiments: 3 male and 3 female per dose; 6 males per dose in main experiment.
Control animals:
yes, concurrent vehicle
Positive control(s):
- cyclophosphamide;
- Justification for choice of positive control(s): none given
- Route of administration: oral gavage
- Doses / concentrations: 80 mg/kg

Examinations

Tissues and cell types examined:
Bone marrow erythrocytes
Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION:
Based on two range-finding studies.

TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields): 500 mg/kg bw, 1000 mg/kg bw and positive control harvested at 24 hours; 2000 mg/kg bw and vehicle control harvested at 24 and 48 hours.


DETAILS OF SLIDE PREPARATION: Giesma stain

METHOD OF ANALYSIS: scored for micronuclei and PCE NCE ratio
Evaluation criteria:
Criteria for positive: Statistically significant increase in micronucleated PCEs or at least one dose level and a statistically significant dose-related response.
Statistics:
ANOVA followed by Dunnett's t-test when ANOVA positive

Results and discussion

Test results
Key result
Sex:
male
Genotoxicity:
negative
Toxicity:
no effects
Remarks:
up to limit concentration
Vehicle controls validity:
valid
Negative controls validity:
not applicable
Positive controls validity:
valid

Any other information on results incl. tables

No clinical toxicity and no cytotoxicity to the bone marrow was observed in any treated animals. No increase in the frequency of micronucleated erythrocytes occurred in any test substance dose.

Table 1: Mean Results of in vivo micronucleus test in mouse bone marrow

 -

Solvent Control (water)

Positive Control (Cyclophosphamide)

Low dose

500 mg/kg bw

Mid dose

1000 mg/kg bw

High dose

2000 mg/kg bw

Sampling time (h)

24

48

24

24

48

24

48

Number of cells analysed

2000

2000

2000

2000

2000

2000

2000

Micronucleated cells per animal %

0.07

0.07

2.73

0.04

0.09

0.02

0.06

Ratio PCE/NCE

0.52

0.47

0.50

0.59

0.44

0.41

0.60

Applicant's summary and conclusion

Conclusions:
ATMP, sodium salt has been tested according to OECD TG 174 under GLP. No increase in the frequency of micronucleated erythrocytes was observed. It is concluded that ATMP-xNa is negative for the induction of micronuclei under the conditions of this test.