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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:
Aug 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
GLP compliance:
yes (incl. QA statement)
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Reference substance name:
Reaction mass of butyl phenyl hydrogen phosphate and diphenyl hydrogen phosphate and phenyl dihydrogen phosphate
EC Number:
950-250-8
IUPAC Name:
Reaction mass of butyl phenyl hydrogen phosphate and diphenyl hydrogen phosphate and phenyl dihydrogen phosphate
Constituent 2
Chemical structure
Reference substance name:
Butan-1-ol
EC Number:
200-751-6
EC Name:
Butan-1-ol
Cas Number:
71-36-3
Molecular formula:
C4H10O
IUPAC Name:
1-Butanol
Test material form:
liquid

Method

Target gene:
histidine gene
Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
Metabolic activation:
with and without
Metabolic activation system:
Type and composition of metabolic activation system:
- source of S9 : The S9 fraction was prepared according to Ames et al. at BASF SE in an AAALAC-approved laboratory in accordance with the German Animal Welfare Act and the effective European Council Directive.
- method of preparation of S9 mix: At least 5 male Wistar rats received 80 mg/kg bw phenobarbital i.p. and ß-naphthoflavone orally each on three consecutive days.
- quality controls of S9 (e.g., enzymatic activity, sterility, metabolic capability): To demonstrate the efficacy of the S9 mix, the S9 batch was characterized with benzo(a)pyrene.
Test concentrations with justification for top dose:
In agreement with the recommendations of current guidelines 5mg/plate or 5µl/plate were generally selected as maximum test dose at least in the 1st experiment. However, this maximum dose was tested even in the case of relatively insoluble test compounds to detect possible mutagenic impurities. Furthermore, doses > 5 mg/plate or 5 µl/plate might also be tested ub repeat experiments for further clarification/substantiation.
Vehicle / solvent:
DMSO
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
4-nitroquinoline-N-oxide
9-aminoacridine
N-ethyl-N-nitro-N-nitrosoguanidine
other: 2-aminoanthracene, 4-nitro-o-phenylenediamine (NOPD)
Details on test system and experimental conditions:
NUMBER OF REPLICATIONS:
- Number of cultures per concentration (single, duplicate, triplicate) : triplicate
- Number of independent experiments : 2

Rationale for test conditions:
The test conditions were according to the test guidelines.
Evaluation criteria:
Acceptance criteria
Generally, the experiment was considered valid if the following criteria were met:
• The number of revertant colonies in the negative controls was within the range of the historical negative control data for each tester strain.
• The sterility controls revealed no indication of bacterial contamination.
• The positive control substances both with and without S9 mix induced a distinct increase in the number of revertant colonies compatible with the range of the historical positive control data or above.
• Fresh bacterial culture containing approximately 109 cells per mL were used.
Assessment criteria
The test substance was considered positive in this assay if the following criteria were met:
• A dose-related and reproducible increase in the number of revertant colonies, i.e. at least doubling (bacteria strains with high spontaneous mutation rate, like TA 98, TA 100 and E.coli WP2 uvrA) or tripling (bacteria strains with low spontaneous mutation rate, like TA 1535 and TA 1537) of the spontaneous mutation rate in at least one tester strain either without S9 mix or after adding a metabolizing system.
A test substance was generally considered non-mutagenic in this test if:
• The number of revertants for all tester strains were within the range of the historical negative control data under all experimental conditions in at least two experiments carried out independently of each other.

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
E. coli WP2
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
No test substance precipitation was found with and without S9 mix.

Applicant's summary and conclusion

Conclusions:
Under the experimental conditions chosen here, it is concluded that Phenyl acid phosphate is not a mutagenic test substance in the bacterial reverse mutation test in the absence and the presence of metabolic activation.
Executive summary:

According to the results of the present study, the test substance did not lead to a relevant increase in the number of revertant colonies without S9 mix or after adding a metabolizing system in two experiments carried out independently of each other (standard plate test and preincubation assay).

The results of the negative as well as the positive controls performed in parallel corroborated the validity of this study, since the values fulfilled the acceptance criteria. The number of revertant colonies in the negative controls, with and without S9 mix, were within the range of the historical negative control data for each tester strain. In addition, the positive control substances with and without S9 mix induced a significant increase in the number of revertant colonies compatible with the range of the historical positive control data.