Registration Dossier

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
experimental study
Adequacy of study:
key study
Study period:
April-December 1988
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study according to OECD guideline 475

Data source

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

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)
Principles of method if other than guideline:
Method: other: No specific protocol guideline cited (e.g., OECD 475: "Mammalian Erythrocyte Micronucleus Test"). General guidelines cited: 40 CFR Part 160, OECD ISBN 92-64-12367-9.
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Identity: Dowanol-DPnB (n-butoxypropoxypropanol or
dipropylene glycol normal-butyl ether).
CAS # 29911-28-2
Appearance: Liquid.
Batch No.: QA001078 (produced in July 1987).
Source: Dow Chemical Europe, Stade, Federal Republic of Germany.
Expiration Date: Not specified
Purity: 99.5%
Specific Gravity: Not specified
Solubility in
water: Not specified
Stability: Not specified
Storage: Not specified
Administered as: Dilution in 1% Methocel and water.

Test animals

Species:
mouse
Strain:
other: CD-1 (ICR) BR
Sex:
male/female

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
1% Methocel*
Duration of treatment / exposure:
Single administration
Frequency of treatment:
Single administration
Post exposure period:
Animals were sacrificed at 24 h, 48 h, 72 h post exposure to test material.
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 250, 833, 2500 mg/kg bw
Basis:
actual ingested
No. of animals per sex per dose:
5 animals per sex per dose per sacrifice time
Control animals:
yes
Positive control(s):
120 mg/kg bw cyclophosphamide

Examinations

Tissues and cell types examined:
Bone marrow was collected from the femur of each animal.  Cells from the bone marrow were transferred to slides, fixed in methanol, and stained in 5% Giemsa.  One thousand polychromatic erythrocytes were evaluated from each animal and the frequencies of micronucleated polychromatic erythrocytes were recorded.

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
not examined
Negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
There were no significant increases in the frequencies of micronucleated polychromatic erythrocytes (MN-PCE) in any of the groups treated with the test chemical compared to negative controls at any dose or time point.  The positive control mice showed significant increases in MN-PCE.

Other metabolism studies show that DPnB reaches the bone marrow of mice.  This in vivo assay confirms that that DPnB is not clastogenic to chromosomal material.  See also General Remark above in the In Vitro Genotoxicity section.

Applicant's summary and conclusion

Conclusions:
Interpretation of results: negative
Under the experimental conditions used, the test chemical was negative in the mouse bone marrow micronucleus test.
Executive summary:

Groups of CD-1 (ICR) BR mice (5/sex/dose/sacrifice time) were administered single doses (by gavage) of 0, 250, 833,
or 2500 mg DPnB/kg body weight.  The positive control chemical was cyclophosphamide (120 mg/kg).  The negative
control chemical (i.e., the diluent for DPnB) was 1% methocel (10 ml/kg).  Groups of animals were sacrificed by
cervical dislocation at three time intervals: 24, 48, and 72 hours after treatment.  Bone marrow was collected from the
femur of each animal.  Cells from the bone marrow were transferred to slides, fixed in methanol, and stained in 5%
Giemsa.  One thousand polychromatic erythrocytes were evaluated from each animal and the frequencies of
micronucleated polychromatic erythrocytes were recorded.

There were no significant increases in the frequencies of micronucleated polychromatic erythrocytes (MN-PCE) in any of
the groups treated with the test chemical compared to negative controls at any dose or time point.  The positive
control mice showed significant increases in MN-PCE.

In conclusion, under the experimental conditions used, the test chemical was negative in the mouse bone marrow micronucleus test.

Other metabolism studies show that DPnB reaches the bone marrow of mice.  This in vivo assay confirms that that DPnB
is not clastogenic to chromosomal material. 

This study was identified as key for this toxicity endpoint because of the methods followed (which were well documented
in the report).  The report included GLP and Quality Assurance statements, signed by the Study Director and Head
of the QA Unit, respectively.  The cell line used, test substance concentrations and dose spacing (4 dose levels
including negative control, with highest being 2500 mg/kg), positive control agent used, the number of cells scored, and
scoring criteria all followed or exceeded guidance as specified in OECD Guideline 475 "Mammalian Erythrocyte
Micronucleus Test."  The positive control agents gave the expected results showing that the animals were responsive to
clastogenic insult.