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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:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Fully documented NTP guideline study report. Read-across based on supporting substance (analogue approach). The data in this record is for the metabolite 2-butoxyethanol (CAS; 111-76-2, EC no 203-905-0) for which the systemic toxicity will be the same. Full details of the justification for the use of an analogue for this end point are included in the document appended to chapter 13 of this dossier.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
yes
Remarks:
data not presented to the detailed degree required by the guideline.
GLP compliance:
not specified
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): 2-butoxyethanol
- Physical state: liquid
- Analytical purity: >99%
- Impurities (identity and concentrations): Water 0.0254%, 0.003% acetic acid, <1000ppm peroxide.
- Lot/batch No.: QP-921215-26D2
- Source: Dow Chemical, Plaquemine, LA
- Stability under test conditions: No degradation detected (monitored for acid, peroxide and by GC)
- Storage condition of test material: Room temperature in the dark.

*NOTE: The above data was specifically associated with the cancer study reported in this reference. It is not clear whether this information also refers to the test material used for this mutagenicity assay.

Test animals

Species:
mouse
Strain:
B6C3F1
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Taconic Laboratory Animals and Services, Germantown, NY
- Age at study initiation: 7-8 weeks
- Weight of animals at study initiation: males: ~25g
- Housing: individual stainless steel, wire bottomed cages.
- Diet: NIH-07 open formulate, pelleted, ad libitum except during exposure period
- Water: tap, ad libitum, automated watering system
- Acclimation period: 18 days in quarantine.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 24C approx
- Humidity (%): 57-58
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

*NOTE: The above data was specifically associated with the cancer study reported in this reference. It is not clear whether this information also refers to the test animals used for this mutagenicity assay.

Administration / exposure

Route of administration:
intraperitoneal
Vehicle:
- Vehicle(s)/solvent(s) used: phosphate buffered saline.
- total dosing volume: 0.4ml
Details on exposure:
No further relevant information
Duration of treatment / exposure:
3 days
Frequency of treatment:
3 doses at 24hour intervals
Post exposure period:
Animals sacrificed 24 hours after final dose
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 17.19, 34.38, 68.78, 137.5, 275, 550, 1100mg/kg/day
Basis:
other: actual dose received.
No. of animals per sex per dose:
5
Control animals:
yes, concurrent vehicle
Positive control(s):
cyclophosphamide
- Doses / concentrations: 10mg/kg

Examinations

Tissues and cell types examined:
erythrocytes
Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION: Preliminary range finder study (not reported.)

DETAILS OF SLIDE PREPARATION: Blood smears prepared from bone marrow cells obtained from femurs. Air dried smears fixed and stained.

METHOD OF ANALYSIS: 2000 polychromatic erythrocytes (PCEs) were scored for the frequency of micronucleated cells.
Evaluation criteria:
No further data
Statistics:
Results analysed with a one-tailed Cochran-Armitage trend test and by pair-wise comparisons between each dosed group and the vehicle control group. Statistically significant results were recorded for P <= 0.025 with the trend test and P <= 0.025 divided by the number of dose groups with the paired comparison test. A final decision on the biological significance (the “final call”) was made on the basis of the statistical analysis, the reproducibility and the magnitude of the effects observed. Data were tabulated as the pooled mean of each exposure group and the standard error of the mean.

Results and discussion

Test results
Sex:
male
Genotoxicity:
negative
Toxicity:
yes
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
See remarks on results below.

Any other information on results incl. tables

All mice in the 1100.00 mg/kg bw dose group died, whereas all mice in the 550 mg/kg bw dose group survived. The frequency of micronucleated PCEs per 1000 cells in the vehicle control group was 2.5 0.2 and the range of means in the dose groups was from 2.3 0.3 at 34.38 mg/kg bw to 3.8 0.8 at 137.50 mg/kg bw. The latter result swas statistically significantly different in a pairwise comparison with the control. The trend test was not significant (P= 0.236) and the paired comparison test gave P = 0.05, whereas P 0.008 was required for statistical significance.

Detailed results

  Micronucleated PCE 's/1000 PCEs      
         
 Vehicle control   2.5 (+/-0.2)     
 Cyclophosphamide  12.9 (+/-1.3)      
 17.19mg/kg  2.6 (+/-0.9)      
 34.38mg/kg  2.3 (+/-0.3)      
68.78mg/kg  3.2 (+/-0.9)      
 137.5mg/kg  3.8 (+/-0.8) *     
275mg/kg  3.7 (+/-0.4)      
 550mg/kg  2.8 (+/-0.4)      

* statistically significantly different from vehicle control.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
2-butoxyethanol does not cause an increase in polychromatic erythrocytes in mice when tested up to overtly toxic doses.
Executive summary:

A reliable in vivo micronucleus induction test was performed with male mice at dose levels up to those causing lethality. The mice were injected intraperitoneally three times at 24 h intervals with 2 -butoxyethanol dissolved in phosphate-buffered saline at dose levels of up to 1100 mg/kg bw per day. All of the animals in the top dose group died; all other animals survived. A statistically significant increase in the number of micronucleated polychromatic erythrocytes was seen in one of the five remaining dose groups in a pairwise comparison with the control (138mg/kg) but as this was not seen in any other dose group sna dhte analysis for trend was not significant this leads to a conclusion of a negative response. This result can be extrapolated to the acetate ester of this substance.