Registration Dossier

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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Acceptable, well documented study which meets basic scientific principles and contains sufficient detail to be able to judge the results reliable as a contribution to the understanding of the toxicity of this substance. Study examined a structural analogue chemical.

Data source

Reference
Reference Type:
publication
Title:
Genotoxic and/or epigenetic effects of some glycol ethers: results of different short-term tests.
Author:
Elias, Z., Danière, M.C., Marande, A.M., Poirot, O., Terzetti, F. & Schneider, O.
Year:
1996
Bibliographic source:
Occup.Hyg., 2, 187-212.

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Principles of method if other than guideline:
cited as being according to recommended standards and guidelines as stated by Heddle et al (Mutat Res, 123, 61-118, 1983) and MacGregor et al (Mutat Res, 189, 103-12, 1987)
GLP compliance:
not specified
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
1-methoxypropan-2-ol is a close structural analogue of 1-ethoxypropan-2-ol, which is the major hydrolysis product of the submission substance (2-ethoxy-1-methyl ether acetate). Details for the surrogate material:
- Analytical purity: Analysed purity 99% .
- Supplied by Merck, manufacturer’s quoted purity >99%
- Impurities: peroxides 0.5-2mg/l.

A detailed justification for read across within the P series glycol ethers is attached to chapter 13 of the IUCLID dossier for this substance.

Test animals

Species:
mouse
Strain:
CD-1
Sex:
male/female
Details on test animals and environmental conditions:
no data

Administration / exposure

Route of administration:
intraperitoneal
Vehicle:
- Vehicle(s)/solvent(s) used: Hank's balanced salt solution, pH 7.2
- Amount of vehicle administered): 0.2ml
Details on exposure:
single dose
Post exposure period:
Sampling times 24, 48 and 72 hours after dosing for three lowest dose groups and 24 hours for two highest dose groups.
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 2500, 4000, 5000, 6000mg/kg
Basis:
other: actual dose received.
No. of animals per sex per dose:
4
Control animals:
yes, concurrent vehicle
Positive control(s):
cyclophosphamide
- Route of administration: intraperitoneal
- Doses / concentrations: 25mg/kg
- control (positive and negative) only sampled at 24 hours

Examinations

Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION: dose levels tested between 12.5 and 70% of LD50

DETAILS OF SLIDE PREPARATION: two femurs were removed from each animal and bone marrow flushed out. Cell suspensions were diluted in vehicle and spun in a centrifuge on to a slide. Two patches/slide and two slides/animal were made. Slides were air dried then fixed in methanol and stained with sequentially: May-Grunwald, May-Grunwald pus phosphate buffer, Giemsa in phosphate buffer before rising in phosphate buffer and drying.

METHOD OF ANALYSIS: 1000 polychromatic erythrocytes/animal scored. Ratio of PCEs to normochromic erythrocytes determined by counting 2000 erythrocytes.
Evaluation criteria:
As described by Schmid in Hollaender "Chemical Mutagens", Plenum Press, NY, 1976

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
yes
Remarks:
lethality
Vehicle controls validity:
valid
Positive controls validity:
valid

Any other information on results incl. tables

Results on mortality at top dose confusing as published in study. Reported that "5 animals died after 48 hour (1 males and 2 females)" . The frequency of micronucleated PCEs per 1000 cells in the vehicle control group was 0.53 0.27 and the range of means in the dose groups was from 0.11 0.10 at 2500 mg/kg bw to 0.53 0.20 at 6000 mg/kg bw, both results being in the 24 hr samples. The intermediate doses gave values between these two but there was no dose response relationship. Values at 48 hours were similar to the 24 hour control value (no 48 hour control values available. There was no clear dose related change in the PCE/NCE ratio at either the 24 h or 48 h observation times from the common, 24 h control value of 1.33 ± 0.9. There appeared to be a slight trend towards an inhibition in the division and maturation of the nucleated erythropoetic cells, as shown but the decrease in PCE/NCE ratio at 24hrs, but the values obtained at the different doses were not statistically significantly different from the control.

Detailed results

 

       Micronucleated PCE %

    PCE/NCE ratio   

 24hr  48hr   24hr  48hr  
 Vehicle  0.53 (+/-0.27)      1.33 (+/-0.09)      
 Cyclophosphamide  9.90 (+/-1.33)       1.27 (+/-0.07)     
  2500mg/kg  0.11 (+/-0.10) 0.54 (+/-0.28)      1.17 (+/-0.07)  1.30 (+/-0.07)   
4000mg/kg  0.36 (+/-0.18)  0.33 (+/-0.16)-   1.06 (+/-0.05)  1.22 (+/-0.09)  
 5000mg/kg  0.12 (+/-0.10)  1.03 (+/-0.33)     1.04 (+/-0.09)  1.03 (+/-0.23)
 6000mg/kg  0.97 (+/-0.39) 0.69 (+/-0.42)      0.96 (+/-0.14) 0.60 (+/- 0.20)    

Applicant's summary and conclusion

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

A reliable in vivo micronucleus induction test was performed with male and female mice at dose levels up to those causing lethality. The mice were injected intraperitoneally with a single dose of the surrogate substance methoxypropanol dissolved in Hank's balance salt solution at doses up to 6000mg/kg bw per day before sampling at 24 and 48 hours. For the positive and negative controls, sampling was only undertaken at 24 hours. Marked lethality was seen at the top dose. There were no statistically significant increases seen in any dose group relative to the control in the number of micronucleated PCE or the PCE/NCE ratio at any time point or concentration, leading to a conclusion of a negative response. This result can be considered representative of the close structural analogue ethoxypropanol, which is in turn the rapidly created in vivo metabolite of ethoxypropyl acetate, the substance that is the subject of this dossier. On this basis, the study indicates that ethoxyypropyl acetate is not mutagenic.

Synopsis: mouse micronucleus test: negative.