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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
Study period:
1998-01-20 to 1998-06-26
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Suboptimal GLP quality; adequate coherence between data, comments and conclusions; deviations to guideline; vehicle control inappropriate (saline although test item was dissolved in distilled water)
Cross-reference
Reason / purpose:
reference to same study

Data source

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

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EPA OTS 798.5395 (In Vivo Mammalian Cytogenics Tests: Erythrocyte Micronucleus Assay)
Deviations:
yes
Remarks:
from EC B.12: top-dose did not induce overt toxicity and was below the recommendation of 2000 mg/kg
GLP compliance:
yes
Remarks:
No laboratory compliance certificate. No analytical certificate for test item. Test item characterization insufficient. No study director-signed GLP declaration.
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Substance type: MCP
- Physical state: solid powder*
- Nominal purity: 99.8%*
- Lot/batch No.: 03907LF
- Expiration date of the lot/batch: not indicated
- Stability under test conditions: not indicated but stability verified in drinking water*
- Storage condition of test material: at room temperature

*: not reported (insufficient test item characterization), but available for the same batch in other studies under 7.8.2

Test animals

Species:
mouse
Strain:
CD-1
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River
- Age at study initiation: approx. 9-11 weeks (not specified)
- Weight at study initiation: 24-32 g
- Assigned to test groups randomly: yes, by body weight
- Fasting period before study: no
- Housing: 5/cage for F, individual for M
- Diet (e.g. ad libitum): ad lib
- Water (e.g. ad libitum): ad lib
- Acclimation period: not indicated

ENVIRONMENTAL CONDITIONS not indicated

IN-LIFE DATES: not indicated

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
- Sterile distilled water
- Justification for choice of solvent/vehicle: highly soluble
- Concentration of test material in vehicle: 50-400 g/L (-> top dose above water solubility limit)
- Amount of vehicle (if gavage or dermal): 10 mL/kg
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
dissolved freshly before dosing
Duration of treatment / exposure:
see below
Frequency of treatment:
Range-finding: up to three times at 24-h intervals
Main test: three times at 24-h intervals
Post exposure period:
all sacrifices 24-h after last dose
Doses / concentrations
Remarks:
Doses / Concentrations:
62.5, 125, 250, 500 and 1000 mg/kg/day
Basis:
actual ingested
main test
No. of animals per sex per dose:
5 (main test)
Control animals:
other: physiological saline, invalid (distilled water was the vehicle)
Positive control(s):
- cyclophosphamide
- Justification for choice of positive control(s): clastogen
- Route of administration: i.p.
- Doses / concentrations: 20 mg/kg once

Examinations

Tissues and cell types examined:
Femoral bone marrow - polychromatic and normochromatic erythrocytes
Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION: see results

DETAILS OF SLIDE PREPARATION:
Smears -> slides; MGG staining

METHOD OF ANALYSIS:
range-finding + main test: random observation of 1000 erythrocytes for myelotoxicity determination (polychromatic and normochromatic)
main test only: random observation of 1000 polychromatic erythrocytes for micronucleus determination
Evaluation criteria:
Compared statistically and vs. background frequencies
Statistics:
ANOVA, Student t-test

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
yes
Remarks:
bone marrow: none; general: lethal at 2000 mg/kg
Vehicle controls validity:
other: valid but wrong vehicle
Negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
RESULTS OF RANGE-FINDING STUDY
- 5/6 dead within 30 min of 1st dose at 4000 mg/kg;
- 4/6 dead within 24h of 1st dose at 2000 mg/kg; survivors dosed twice at 1000 and 500 mg/kg: no death and no myelotoxic effect
- 4000 and 2000 mg/kg were respectively above and around the solubility limit (~200 g/L)
- Rationale for exposure: none indicated, but serum perchlorate levels evidenced in human studies after oral or inhalative exposures

RESULTS OF DEFINITIVE STUDY
- Induction of micronuclei (for Micronucleus assay): no, within background frequencies
- Ratio of PCE/NCE (for Micronucleus assay): within background frequencies
- Appropriateness of dose levels and route: yes
- Statistical evaluation: significant increase for positive control only

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
Absence of in vivo genotoxic potential in a standard assay at up to 1000 mg/kg (non-toxic dose, but close to the lethal dose of 2000 mg/kg).
Executive summary:

Ammonium perchlorate was provided to groups of 5 male and 5 female mice by gavage in distilled water, at up to 1000 mg/kg/day on three consecutive days. The bone marrow from each mouse was assessed for micronucleus formation at sacrifice. Cyclophosphamide was administered i.p. to additional mice, as a positive control.

  • Vehicle control was invalid (wrong vehicle: physiological saline) but negative. This validates the study design's specificity.
  • The positive control induced a significant, 8 to 10-fold increase in micronucleus frequency but no myelotoxicity. This validates the study design's sensitivity.
  • Ammonium perchlorate induced no significant increase in micronucleus frequency or myelotoxicity vs. vehicle controls or historical frequencies. The top-dose was expected to be toxic as it was close to the lethal dose of 2000 mg/kg (after single dosing), but induced no toxicity.