Registration Dossier

Toxicological information

Genetic toxicity: in vivo

Currently viewing:

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
1990
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well reported guideline study.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1990

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EPA OTS 798.5395 (In Vivo Mammalian Cytogenics Tests: Erythrocyte Micronucleus Assay)
Deviations:
no
GLP compliance:
not specified
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Triethylene glycol monomethyl ether (TGME)
- Molecular formula (if other than submission substance): CH3-O-C2H4-O-C2H4-O-C2H4-OH
- Molecular weight (if other than submission substance): 162
- Physical state: Liquid
- Analytical purity: 99.23%
- Lot/batch No.: 1-BBF-48-10
- Supplier: Union Carbide Chemicals & Plastic Company Inc.

Test animals

Species:
mouse
Strain:
CD-1
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Inc., Wilmington, MA.
- Age at study initiation: 8 weeks old
- Assigned to test groups randomly: [no/yes, under following basis: ]
- Housing: Individually in wire-bottom cages with a computer-generated unique identification number.
- Diet: Purina Certified Rodent Chow #5002 (Ralston Purina Company, Richmond, IN ad libitum
- Water: Municipal water ad libitum
- Acclimation period: One week

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
- Vehicle(s)/solvent(s) used: water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
The test material and CP were dissolved in distilled water. Freshly prepared solutions (less than 2 hours old) were used for dosing the animals. The concentrations of the test material in the dosing solutions used for the micronucleus test were verified by high pressure liquid chromatography (HPLC) by the Analytical Chemistry Laboratory, Health and Environmental Sciences, The Dow Chemical Company, Freeport, Texas (Hinze, 1989).

- All doses of the test material and CP were administered by single oral gavage in aliquots of 10 ml/kgBW. Negative control mice received 10 ml/kgBW water.
Duration of treatment / exposure:
Single Dose.
Frequency of treatment:
Single Dose.
Post exposure period:
24, 48 and 72 hours.
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0, 500, 1667, 5000mg/kg/BW
Basis:
other: treatment
Remarks:
Doses / Concentrations:
0, 50 ,166.7, 500 mg/ml
Basis:
nominal conc.
target concentration
Remarks:
Doses / Concentrations:
0, 53.3, 174, 517 mg/ml
Basis:
analytical conc.
No. of animals per sex per dose:
5
Control animals:
yes
Positive control(s):
cyclophosphamide at a dose level of 120 mg/kgBW.

Examinations

Tissues and cell types examined:
Bone marrow polychromatic erythrocytes
Details of tissue and slide preparation:
DETAILS OF SLIDE PREPARATION: Cell smears were prepared on microscope slides using small portions of the cell suspension. The slides were allowed to air dry, fixed in methanol and stained in 5% Giemsa.

METHOD OF ANALYSIS:
The slides were coded and scored blindly. One thousand polychromatic erythrocytes were examined from each animal and the number of micronucleated polychromatic erythrocytes (MN-PCE) was recorded. Micronuclei were identified as darkly stained bodies with sharp contours and varying shapes such as round, almond, or ring. The ration of PCE-NCE in the bone marrow was determined by examining 1000 erythyrocytes. The ration was expressed as PCEx100/PCE+NCE.
Evaluation criteria:
The final interpretation of biological significance of the responses was based on both statistical outcome and scientific judgment.
Statistics:
The raw data on the counts of MN-PCE for each animal were first transformed by adding 1 to each count and then taking natural log of the adjusted number. The transformed MN-PCE data and the data on percent PCE were analyzed by a three-way analysis of variance (sex, dose, and time), assuming the three-way interaction to be zero. From this initial analysis, the two-way interactions were reviewed for significance. Depending upon this review, the data were analyzed by either one, two, or three-way analysis of variance looking only at main effects. Pairwise comparisons of treated vs. negative control groups were done, if necessary, by a t-test using Bonferroni correction for multiple comparisons. The alpha level at which all the tests were conducted was 0.01.

The final interpretation of biological significance of the responses was based on both statistical outcome and scientific judgment.

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
no effects
Remarks:
based on lethality
Positive controls valid:
yes
Additional information on results:
RESULTS OF RANGE-FINDING STUDY
- Clinical signs of toxicity in test animals: All animals survived.
- High dose with and without activation: 5000mg/kg/BW

Any other information on results incl. tables

One female treated with 1667 mg/kgBW TGME died prior to the scheduled time of sacrifice. There were no significant differences in MN-PCE frequencies between the groups treated with the test material and the negative controls.  The ratios of PCE to NCE observed in the groups treated with the test material were not significantly different form those of the negative control mice.  The body weight data indicated that the animals did not experience any undue stress following treatments. 

The positive control chemical, CP, induced a significant increase in the frequencies of micronucleated polychromatic erythryocytes in the bone marrows of both males and females.

Summary of frequencies of micronucleated polychromatic erythrocytes (PCE) in the bone marrow of males.

Concentration (mg/kgbw)

24 hours

48 hours

72 hours

 

PCE

% PCE

PCE

% PCE

PCE

% PCE

-ve control

1.0 (1.2)

71.1 (4.7)

0.6 (0.9)

78.7 (6.9)

0.6 (0.9)

74.0 (8.7)

500

0.8 (1.3)

79.1 (7.6)

0.4 (0.5)

79.4 (5.9)

0.8 (0.8)

76.6 (7.5)

1667

0.2 (0.4)

68.2 (7.4)

0.4 (0.9)

76.8 (11.1)

0.0 (0.0)

76.5 (14.6)

5000

0.6 (0.9)

68.8 (14.5)

0.2 (0.4)

79.4 (13.4)

0.4 (0.5)

75.3 (8.1)

+ve control

62.2 (32.6)*

67.3(16.4)

Not tested

–ve control = water, +ve control = cyclophosphamide (120mg/kg). N=5. Figures in brackets are standard deviations. *=significant (p<0.01) from negative control.

Summary of frequencies of micronucleated polychromatic erythrocytes (PCE) in the bone marrow of females.

Concentration (mg/kgbw)

24 hours

48 hours

72 hours

 

PCE

% PCE

PCE

% PCE

PCE

% PCE

-ve control

0.4 (0.9)

73.5 (6.8)

1.2 (0.8)

70.6 (9.8)

0.4 (0.5)

76.7 (11.5)

500

0.4 (0.5)

78.3 (4.8)

0.6 (0.5)

80.8 (5.9)

0.4 (0.9)

81.2 (4.5)

1667

0.2 (0.4)

74.8 (2.9)

0.0 (0.0)

80.2 (4.9)

0.6 (0.5)

82.0 (5.0)

5000

1.6 (0.9)

69.6 (8.7)

0.4 (0.5)

72.1 (6.3)

1.2 (1.3)

76.2 (9.8)

+ve control

34.6 (9.8)*

74.0 (8.1)

Not tested

–ve control = water, +ve control = cyclophosphamide (120mg/kg). N=5 (except 48hr, 1667 when one animal died prior to scheduled sacrifice time). Figures in brackets are standard deviations. *=significant (p<0.01) from negative control.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
Based upon the results, it was concluded that the test chemical did not induce a significant increase in the frequencies of micronucleated bone marrow polychromatic erythryocytes when given as single oral dose to male and female CD-1 (ICR) BR mice. Hence, under the experimental conditions used, the test chemical was judged negative in the mouse bone marrow micronucleus test.
Executive summary:

In a guideline (TSCA) study, TGME did not increase the frequency of micronucleated polychromatic erythrocytes in the bone marrow of mice treated by a single gavage dose up to 5000 mg/kg/day. The percentage of PCEs in bone marrow was also not reduced by TGME treatment.