Reaction products of diazotised 2-amino-4-nitrophenol, subsequently coupled with 7-Anilino-4-hydroxy-2-naphthalenesulfonic acid, further mixed with Chromium, [3-(hydroxy-κO)-4-[2-[2-(hydroxy-κO)-1-naphthalenyl]diazenyl-κN1]-7-nitro-1-naphthalenesulfonato(3-)]-, sodium salts

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

31 October – 13 November 2018

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

July 1997

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: modified method by Prival et al. (1984) for azo dyes

Version / remarks:

1984

Principles of method if other than guideline:

None

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Test material form:

solid: particulate/powder

Method

Target gene:

histidine operon

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

Metabolic activation:

with and without

Metabolic activation system:

Hamster S9

Test concentrations with justification for top dose:

0.40 - 6.30 mg/plate

Vehicle / solvent:

yes

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

9-aminoacridine

2-nitrofluorene

sodium azide

congo red

cumene hydroperoxide

other: 2-Aminoanthracene

Details on test system and experimental conditions:

The test substance is preincubated with the tester strain and sterile buffer (for
volume compensation) or the metabolic activation system for 30 minutes +/- 5 min. at 30°C
+/- 3°C. Subsequently the overlay agar is added and the mixture is poured on the surface of a
minimal agar plate. In addition deviating from the standard method a reductive metabolic
activation system with the reductive agent Flavinemononucleotide and with 30% uninduced
hamster S9 is applied.

Evaluation criteria:

The colonies were counted manually with a colony counter (Heathro Scientific LLC). The
mean value and standard deviation of the three resp. five replicates were calculated
(Microsoft Excel®). The resulting induction rates (IR = number of revertant colonies in the
plate with test substance / mean number of revertant colonies in the negative control plate
[NC]) were calculated for each test concentration and each tester strain.
Cytotoxic effects of the test item can be determined if the growth of the micro colonies in the
background lawn deviates from the negative control plates. A decrease in micro colonies
density or gaps in the bacterial background lawn are indicators for cytotoxic effects. These
are discovered by microscopic evaluation of the plates. Often such effects can be observed
in combination with reduced number of revertant colonies in comparison to the number of
spontaneous revertant colonies on the negative control plates (induction rate < 1). Toxic
effects to the bacteria are reported.
According to OECD Guideline 471 a sample is mutagenic if there is a concentration-related
increase over the range tested and/or a reproducible increase at one or more concentrations
in the number of revertant colonies per plate in at least one strain with or without the
metabolic activation system. Statistical methods may be used as an aid in evaluating the test
results. However, statistical significance should not be the only determining factor for a
positive result. For the evaluation of the results of the tests performed in this study the increase of revertants
in a sample is expressed as the induction rate [IR], (IR = number of revertants in the
sample/number of revertants in the control). In the case of a reproducible increase of the
number of revertants and if additionally a statistically significant difference between the mean
values can be demonstrated for example with the U-test according to Mann & Whitney e.g.,
the sample is evaluated as positive.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 3

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 4

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 5

Key result

Species / strain:

S. typhimurium TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

With the highest test concentrations of 5 mg/plate and 2.5 mg/plate there were some hints of
cytotoxic effects for the tester strains of TA 98 (+/- S9), TA 1535 (-S9) and TA 1537 (+/- S9).

Applicant's summary and conclusion

Conclusions:

BLACK 407 is evaluated as mutagenic in the Ames Test modified by Prival.

Executive summary:

In the study five concentrations between 6.30 mg/plate and 0.40 mg/plate of the test item corresponding to 5 mg/plate to 0.31 mg/plate of the active test substance were applied. The test was performed with and without reductive metabolic activation with preincubation and non-induced Hamster S9. In four of the tester strains (TA 98, TA 100, TA 1535 and TA 1537) a dose dependent increase of revertant colonies or a reproducible increase at one or more concentrations in the number of revertant colonies per plate with or without metabolic activation were occurred.

The test item is evaluated as mutagenic in the Ames Test modified by Prival.