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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
15 October 1991 - 13 January 1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Only 4 guideline strains were used.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992
Report date:
1991

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
Only 4 relevant strains were used.
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
1,2-diethoxypropane
EC Number:
412-180-1
EC Name:
1,2-diethoxypropane
Cas Number:
10221-57-5
Molecular formula:
C7H16O2
IUPAC Name:
1,2-diethoxypropane
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Synthetic Chemicals; 9059

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: In the dark at ambient temperature.

Method

Species / strain
Species / strain / cell type:
other: S. typhimurium TA 1535, TA 1537, TA 1538, TA 98 and TA 100
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254-induced rat liver S9
Test concentrations with justification for top dose:
Preliminary test in S.typhimurium TA100: 33, 100, 333, 1000, 3333, 10000 µg/plate
Main tests: 33, 100, 333, 1000, 3333, 10000 µg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
2-nitrofluorene
sodium azide
other: With S9: 2-Aminoanthracene (2-AAN), 2 µg per plate with TA 1535 and TA 1537 and 0.5 µg per plate with TA 1538, TA 98 and TA 100
Details on test system and experimental conditions:
METHOD OF APPLICATION: preincubation

DURATION
- Preincubation period: 20 minutes
- Exposure duration: 48 hrs

NUMBER OF REPLICATIONS: 2

DETERMINATION OF CYTOTOXICITY
- Method: background lawn activity


Evaluation criteria:
A test was considered acceptable if for each strain:

i) the bacteria demonstrated their typical responses to crystal violet, ampicillin and u.v. light.
ii) at least 2 of the vehicle control plates were within the following ranges: TA 1535, 4-30; TA 1537, 1-20; TA 98, 10-60; TA 100, 60-200 and TA 1538, 5-35.
iii) on at least 2 of the positive control plates there were x 2 the mean vehicle control mutant numbers per plate, or in the case of TA 100, x 1.5 the mean vehicle control mutant numbers per plate. If the mean colony count on the vehicle control plates was less than 10 then a value of 10 was assumed for assessment purposes. In such cases a minimum count of 20 was required on at least 2 of the positive control plates.
iv) no toxicity or contamination was observed in at least 4 dose levels.
v) in cases where a mutagenic response was observed, that no more than one dose level was discarded before the dose which gave the highest significant mean colony number.

Where these criteria were met, a significant mutagenic response was recorded if there was:
i) for S. typhimurium strains TA 1535, TA 1537, TA 1538 and TA 98, at least a doubling of the mean concurrent vehicle control values at some concentration of the test substances and, for S. typhimurium strain TA 100, a 1.5-fold increase over the control value. If the mean colony count on the vehicle control plates was less than 10 then a value of 10 was assumed for assessment purposes. In such cases a minimum count of 20 was required before a significant mutagenic response was identified.
ii) a dose related response, although at high dose levels this relationship could be inverted because of, for example, (1) toxicity to the bacteria generally, (2) specific toxicity to the mutants and (3) inhibition of foreign compound metabolising enzymes where mutagens require metabolic activation by the liver.
iii) a reproducible effect in independent tests.

Results and discussion

Test results
Species / strain:
other: S. typhimurium TA 1535, TA 1537, TA 1538, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
10,000 µg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: There was no precipitation of the test material.

RANGE-FINDING/SCREENING STUDIES:
A toxicity test using strain TA 100 only was performed in the presence and absence of 59 mix to establish suitable dose levels for the mutation tests. One plate of each of the following concentrations
of 1,2-Di-ethoxy-propane was used: 33, 100, 333, 1000, 3333, 10000 µg/plate. A thin lawn of microcolonies was noted at 10000 µg/plate indicating toxicity to the bacteria (Table 1).

HISTORICAL CONTROL DATA (with ranges, means and standard deviation and confidence interval (e.g. 95%)
- Positive historical control data: No
- Negative (solvent/vehicle) historical control data: The vehicle control values were within the normal ranges experienced in the laboratory (no dates provided) and reported in the literature with these strains of S. typhimurium.

Applicant's summary and conclusion

Conclusions:
In a bacterial reverse mutation assay (Amest test), 1,2-Diethoxypropane was negative with and without Aroclor 1254-induced rat liver S9 metabolic activation.
Executive summary:

In a reverse gene mutation assay in bacteria (8341), strains of S. typhimurium TA 1535, TA 1537, TA 1538, TA 98 and TA 100 were exposed to 1,2-Diethoxypropane in DMSO at concentrations of 0, 33, 100, 333, 1000, 3333, 10000 µg/plate (pre-incubation, both experiments) in the presence and absence of mammalian metabolic activation (Aroclor-1254 induced rat liver S9).

1,2-Diethoxypropane was tested beyond the limit concentration of 5000 µg/plate. The positive controls induced the appropriate responses in the corresponding strains. There was no evidence of induced mutant colonies over background.