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Toxicological information

Genetic toxicity: in vitro

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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:
October 10, 1997 - November 3, 1997
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study followed guidelines similar to U. S. EPA, EEC, OECD and MAFF guidelines and in accordance with the principles of GLP.
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998
Report Date:
1998

Materials and methods

Test guidelineopen allclose all
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 472 (Genetic Toxicology: Escherichia coli, Reverse Mutation Assay)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
EPA OPPTS 870.5100 - Bacterial Reverse Mutation Test (August 1998)
Deviations:
no
Principles of method if other than guideline:
not applicable
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Purity was 99.3%, contained 1.2 ppm peroxide

Method

Target gene:
Histidine operon, rfa wall, uvr B gene
Species / strain
Species / strain / cell type:
other: S. typhimurium TA98, TA100, TA1535, TA1537 and E. coli WP2uvrA
Details on mammalian cell type (if applicable):
None
Additional strain / cell type characteristics:
not specified
Metabolic activation:
with and without
Metabolic activation system:
S-9 (40.7 mg protein/ml) from male Sprague-Dawley rats that had been injected i.p. with 500 mg/kg Aroclor 1254
Test concentrations with justification for top dose:
0, 100, 333, 1000, 3330 and 5000 micrograms/plate +/- S9 mix (initial study); 0, 313, 625, 1250, 2500 and 5000 micrograms/plate +/- S9 mix (confirmatory study). Analytical concentrations of stock solutions were 89-97% (initial study) and 95-99% (confirmatory study) of target.
Vehicle / solvent:
deionized water
Controls
Untreated negative controls:
not specified
Negative solvent / vehicle controls:
yes
Remarks:
50 microliters deionized water
True negative controls:
not specified
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene, 2-nitrofluorene, benzo(a)pyrene, sodium azide, ICR-191 or 4-nitroquinoline-N-oxide (depending on strain)
Details on test system and experimental conditions:
The tester strain and the S9 mix (where appropriate) were preincubated for 20 +/- 2 min at 37 +/- 2 degrees C prior to the addition of molten, selective overlay agar. The agar and preincubation reaction mixture were mixed and overlaid onto a minimal agar plate. Following incubation at 37 +/- 2 degrees C for 52 +/- 4 hr, revertant colonies were counted manually (vehicle control or test material) or by automated colony counter (positive controls). All doses of test material, vehicle and positive controls were tested in triplicate. The condition of the background lawn was evaluated for evidence of cytotoxicity or test material precipitation. Adequate tester strain integrity, initial density requirements and S9 activity were demonstrated.
Evaluation criteria:
For a test material to be considered positive, it had to produce at least a 3-fold (TA98, TA1535, TA 1537 and WP2uvrA) or 2-fold, dose-related and reproducible increase in the mean revertants per plate of at least one tester strain (compared to the vehicle control). A response that did not meet all 3 of the criteria (magnitude, dose-responsiveness, reproducibility) was not evaluated as positive.
Statistics:
For all replicate platings, the mean revertants per plate and the standard deviation were calculated.

Results and discussion

Test results
Species / strain:
other: S. typhimurium TA98, TA100, TA1535, TA1537 and E. coli WP2uvrA
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
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
All criteria for a valid study were met. Both studies were negative.
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

None

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

The results of the Salmonella - Escherichia coli/Marnmalian-Microsome Reverse Mutation Assay Preincubation Method with a Confirmatory Assay indicate that under the conditions of this study, test article Dipropylene glycol n-propyl ether (Dowanol DPnP), did not cause a positive increase in the number of revertants per plate of any of the tester strains either in the presence or absence of microsomal enzymes prepared from AroclorTM-induced rat liver (S9).
Executive summary:

Dipropylene glycol n-propyl ether (Dowanol DPnP) was evaluated in the Salmonella-Escherichia coli / mammalian-microsome bacterial mutagenicity assay using a pre-incubation modification of the standard method with a confirmatory assay. The test was conducted in the presence and absence of an externally supplied metabolic activation system (S-9) using Salmonella typhimurium tester strains TA98, TA100, TA1535, and TA1537 and Escherichia coli tester strain WP2uvrA.

The concentrations of the test material in the presence and absence of S9 mix ranged from 100 to 5000 pg per plate. The results were confirmed in an independent repeat assay.

The results indicate that Dowanol DPnP did not cause a positive increase in the number of revertants per plate of any of the tester strains in this bacterial mutagenicity test under the experimental conditions used.