Oxydipropyl dibenzoate

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 July 1997- 5 August 1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1998

Report date:

1998

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 472 (Genetic Toxicology: Escherichia coli, Reverse Mutation Assay)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)

Deviations:

no

Test guideline 4

Qualifier:

according to guideline

Guideline:

EPA OTS 798.5265 (The Salmonella typhimurium Bacterial Reverse Mutation Test)

Deviations:

no

Test guideline 5

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5100 - Bacterial Reverse Mutation Test (August 1998)

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Benzoflex 9-88

IUPAC Name:

Benzoflex 9-88

Constituent 2

Reference substance name:

Oxydipropyl dibenzoate

EC Number:

248-258-5

EC Name:

Oxydipropyl dibenzoate

Cas Number:

27138-31-4

Molecular formula:

C20H22O5

IUPAC Name:

oxydipropyl dibenzoate

Details on test material:

- Name of test material (as cited in study report): Benzoflex 9-88 (Dipropylene glycol dibenzoate DPGDB)
- Physical state: Clear colourless liquid
- Storage condition of test material: Room temperature

Method

Target gene:

This system employs mutant strains of Escherichia coli which are incapable of synthesising the amino acid tryptophan required for growth.
The strains used carry additional mutations which render them more sensitive to mutagens. The S. typhimurium strains have a defective cell coat which allows greater permeability of test substances into the cell. All the strains are deficient in normal DNA repair processes. In addition three of them possess a plasmid pKM101 which introduces an error prone repair process resulting in increased sensitivity to some mutagens.

Species / strain

Species / strain 1

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Species / strain 2

Species / strain / cell type:

E. coli WP2 uvr A pKM 101

Metabolic activation:

with and without

Metabolic activation system:

S-9 mix

Test concentrations with justification for top dose:

First test - 5000, 1500, 500, 150, 50, 15, and 5 µg/plate plus a vehicle control.
Second test - 5000, 1500, 500, 150, and 50 µg/plate, plus a vehicle control.

Vehicle / solvent:

- Solvent used: DMSO
- Justification for choice of solvent/vehicle: The test material is poorly soluble in water. The solubility at 50 mg/mL was assessed in DMSO, ethanol, methanol, and acetone and the test substance was found to be fully soluble in each solvent tested. DMSO was selected as the solvent following confirmation by the sponsor. This solvent is the most commonly used solvent within the testing laboratory when water is not suitable.

Controls

Controls 1

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

N-ethyl-N-nitro-N-nitrosoguanidine

Remarks:

5 µg/plate for TA1535, 3 µg/plate for TA100, and 2 µg/plate for CM891 Migrated to IUCLID6: In the absence of S9 mix

Controls 2

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

9-aminoacridine

Remarks:

80 µg/plate for TA1537 Migrated to IUCLID6: In the absence of S9 mix

Controls 3

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

2-nitrofluorene

Remarks:

1 µg/plate for TA98 Migrated to IUCLID6: In absence of S9 mix

Controls 4

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

other: 2-Aminoanthracene

Remarks:

In the presence of S9 mix. 2 µg/plate for TA1535; 10 µg/plate for CM891.

Controls 5

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

benzo(a)pyrene

Remarks:

5µg/plate for TA1537, TA98, and TA100 Migrated to IUCLID6: In presence of S9 mix

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation); preincubation (second test only)


DURATION
- Preincubation period: 30 minutes (second test only)
- Exposure duration: 3 days


SELECTION AGENT (mutation assays): Histidine / tryptophan deficient agar


NUMBER OF REPLICATIONS: 3 replicate plates per concentration per strain


DETERMINATION OF CYTOTOXICITY
- Method: observation of the number of revertant colony counts and the presence or absence of the background bacterial lawn

Evaluation criteria:

The number of revertant colony counts for each test or positive control plate was determined and compared to the relevant concurrent vehicle control.

Results and discussion

Test results

Test results 1

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 2

Species / strain:

E. coli WP2 uvr A pKM 101

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS

- Water solubility: In the first test, at 5000 µg and 1500 µg/plate when the test substance solution was mixed with the top agar, a cloudy solution formed with globules apparent at the higher level.; slight cloudiness was observed at 500 µg/plate and at 150 µg/plate there was no observable cloudiness. In all cases the appearance was similar once the agar had set on the plates.
In the pre-incubation assay, a cloudy solution formed with a few small globules at 5000 µg/plate, a cloudy solution with no globules was observed at 1500 µg and 500 µg/plate; a slightly cloudy solution was observed at 150 µg/plate, and at 50 µg/plate no cloudiness was observed. In all cases, the appearance was similar following the pre-incubation period.


COMPARISON WITH HISTORICAL CONTROL DATA: The mean revertant colony counts for the solvent controls were within the historical range.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

It is concluded that DPGDB showed no evidence of mutagenic activity in this bacterial system.

Executive summary:

A bacterial reverse mutation assay was performed to assess the potential of the test material DPGDB to cause gene mutation. The study was conducted according to OECD, EC, US EPA and Japanese test guidelines and in compliance with GLP.

DPGDB was tested against four strains of Salmonella typhimurium and one strain of Escherichia coli, both in the presence and in the absence of metabolic activation (provided by S9 mix). Relevant positive controls were tested concurrently and provided positive results, demonstrating the sensitivity of the assay.

No increases in the number of revertant colonies relative to the concurrent vehicle controls were observed for the test material in any of the strains tested. It was concluded that DPGD showed no evidence of mutagenic activity in this bacterial system.