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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration
Type of information:
experimental study
Adequacy of study:
key study
Study period:
15-Aug-1983 to 04-Nov-1983
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
There is some inaccuracy with respect to test substance identity.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1983
Report Date:
1983

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)
Deviations:
yes
Remarks:
(insufficient cells scored for aberrations and for mitotic index)
GLP compliance:
yes
Type of assay:
chromosome aberration assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Kingston, New York, USA
- Age at study initiation: 64 days
- Weight at study initiation: 275-286 g males, 198-204 g females
- Assigned to test groups randomly: yes, via computer-generated random numbers
- Fasting period before study: no data
- Housing: individually in wire mesh cages
- Diet (e.g. ad libitum): Purina Lab Meal #5001, ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-23
- Humidity (%): 74-83
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12 / 12

IN-LIFE DATES: From: 15-Aug-1983 To: 17-Aug-1983

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
- Vehicle(s)/solvent(s) used: water
- Justification for choice of solvent/vehicle: no data, but well-known vehicle
- Concentration of test material in vehicle: 20, 66 and 197 mg active acid/ml
- Amount of vehicle (if gavage or dermal): 10 ml/kg bw
- Purity: distilled
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
Freshly prepared on the day of administration
Duration of treatment / exposure:
Single oral gavage dose; post-treatment sampling times were 6, 12, 24 and 48 hours
Frequency of treatment:
Once
Post exposure period:
6, 12, 24 and 48 hours
Doses / concentrationsopen allclose all
Dose / conc.:
200 other: mg active acid/kg bw
Remarks:
Calculated from nominal concentration of test substance
Dose / conc.:
660 other: mg active acid/kg bw
Remarks:
Calculated from nominal concentration of test substance
Dose / conc.:
1 970 other: mg active acid/kg bw
Remarks:
Calculated from nominal concentration of test substance
No. of animals per sex per dose:
6
Control animals:
yes, concurrent vehicle
Positive control(s):
cyclophosphamide
- Justification for choice of positive control(s): no data, but well-known clastogen
- Route of administration: oral gavage
- Doses / concentrations: 40 mg/kg bw

Examinations

Tissues and cell types examined:
Bone marrow
Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION: Selected on the basis of a range-finding test in which no effect on mortality or mitotic index and minimal clinical signs were observed at the top dose of 1970 mg active acid/kg bw only; all 3 dose levels analysed.

TREATMENT AND SAMPLING TIMES (in addition to information in specific fields): Colchicine administered 4, 10, 22 and 46 hours after treatment; animals sacrificed 2 hours later.

DETAILS OF SLIDE PREPARATION: Bone marrow cells collected from femurs by aspiration into Hank's Balanced Salt Solution; after centrifugation, supernatant decanted and cells suspended in warm 0.075 M KCl for 25 minutes; cells fixed using 3:1 methanol:acetic acid fixative; chilled then dispersed on glass microscope slides (2/animal) and air dried; stained with Giemsa and mounted with glass coverslips.

METHOD OF ANALYSIS: Slides coded; attempted to examine >=60 metaphases from 5/6 rats per sex per group (if not possible, 6th animal also analysed); 48-hour timepoint not analysed; for each animal, data recorded included numbers and types of chromosome aberrations, mitotic index (500 cells/animal), modal number for each metaphase; chromosome aberrations were classified as chromatid breaks, chromosome breaks, chromatid and chromsome gaps, exchanges, cells with >10 aberrations, pulverized cells.
Evaluation criteria:
No data
Statistics:
Mean mitotic index, mean modal number, percent aberrant cells and mean number of aberrations per cell analysed by Kruskall-Wallis non-parametric non-parametric analysis of variance and non-parametric pairwise group comparisons. Body weight analysed by analysis of covariance. All tests one-tailed.

Results and discussion

Test results
Key result
Sex:
male/female
Genotoxicity:
negative
Toxicity:
yes
Remarks:
body weight loss, clinical observations
Vehicle controls validity:
valid
Negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
RESULTS OF RANGE-FINDING STUDY
- Dose range: 200, 660, 1970 mg active acid/kg bw
- Solubility: miscible with water
- Clinical signs of toxicity in test animals: no mortality; "a few abnormal clinical observations were observed at the highest dose"
- Evidence of cytotoxicity in tissue analyzed: no effect on mitotic index
- Rationale for exposure: slight toxicity at the highest dose
- Harvest times: observed 1 day after dosing
- High dose with and without activation: not applicable
- Other:

RESULTS OF DEFINITIVE STUDY
- Types of structural aberrations for significant dose levels (for Cytogenetic or SCE assay): none
- Appropriateness of dose levels and route: no data
- Statistical evaluation:
- no statistically significant increase in chromosome damage at any dose at any timepoint in either sex; positive control (24 hours) statistically significantly incresased
- no statistically significant change in mitotic index
- no statistically significant change in mean modal number

Any other information on results incl. tables

3/12 animals died when treated with 1970mg/kg.  Mild clinical signs seen at this dose.  Loss of body weight in top dose animals (both sexes) over 48 hours observed. No evidence of mitotic delay so 48 hour animals not analyzed.

Table 1 Results of Chromosome aberration study

Treatment (mg/kg bw)

Treatment time (hrs)

Number of animals analyzed per group

Number of cells analyzed

% aberrant cells per group

Control

6

12

600

0.5

200

6

11

600

0

660

6

11

600

0.3

1970

6

11

600

0.5

Control

12

10

600

0

200

12

11

600

0

660

12

11

561

0.2

1970

12

10**

600

0.2

Control

24

11

540

0

Positive control

24

12

280

7.9

200

24

11

540

0.2

660

24

11

540

0

1970

24

10**

540

0.6

** Animals found dead prior to sacrifice

Applicant's summary and conclusion

Conclusions:
In a reliable study, conducted using a protocol similar to OECD guideline 475, no evidence of clastogenicity was seen in rat bone marrow following a single oral gavage administration at doses up to the maximum tolerated dose of 1970 mg active acid/kg bw. The study was performed in compliance with GLP.