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Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information
Ammonium thiocyanate was negative in the Ames test. Sodium thiocyanate is negative in an in vitro chromosome aberration study and an in vitro mammalian mutagenicity study.
Link to relevant study records
Reference
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:
25 April 1988 - 6 May 1988
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to GLP and OECD471. Formally there is a deficiency due to lack of strains for capable of detecting cetain oxidising or cross-linking agents. This is not suspected to be of impact to thiocyantes.
Reference:
Composition 0
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Principles of method if other than guideline:
With this test it is not possible to identify certain oxidising mutagens, cross-linking agents and hydrazines. Such substances may be detected by E.coli WP2 strains or S. typhimurium TA102 which have an AT base pair at the primary reversion site in stead of GC base pairs which the strains tested in this study have. No independent repeat was performed.
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay
Test material information:
Composition 1
Target gene:
the histidine operon
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Additional strain characteristics:
other: see: "any other information....."
Metabolic activation:
with and without
Metabolic activation system:
S9-Mix
Species / strain:
S. typhimurium TA 1538
Additional strain characteristics:
other: see: "any other information....."
Metabolic activation:
with and without
Metabolic activation system:
S9-mix
Test concentrations with justification for top dose:
50, 100, 500, 1000, 2500 and 5000 µg/plate
Vehicle:
water
Negative controls:
yes
Solvent controls:
yes
Remarks:
water
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: see: "any other information....."
Details on test system and conditions:
METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Preincubation period: not applicable
- Exposure duration: 48 hours
- Expression time (cells in growth medium): 48 hours
- Selection time (if incubation with a selection agent): not applicable
- Fixation time (start of exposure up to fixation or harvest of cells): not applicable

SELECTION AGENT (mutation assays): histidine

NUMBER OF REPLICATIONS: triplicate

NUMBER OF CELLS EVALUATED: The reverted colonies were counted automatically with an Artec Colony Counter (M 880).

DETERMINATION OF CYTOTOXICITY
- Method: number of colonies

Evaluation criteria:
Not stated in the report. Performed according to OECD471
There are several criteria for determining a positive result, such as 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 metabolic activation system.
Biological relevance of the results should be considered first. 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 response. A test substance for which the results do not meet the above criteria is considered nonmutagenic in this test.
Statistics:
Not stated in the report.
Species / strain:
other: S. typhimutium TA98, TA100, TA1535, TA1538 and TA1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity:
no
Vehicle controls valid:
yes
Negative controls valid:
not examined
Positive controls valid:
yes
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: no data
- Effects of osmolality: no data
- Evaporation from medium: no data
- Water solubility: water us the vehicle
- Precipitation: not observed
- Other confounding effects: no data

RANGE-FINDING/SCREENING STUDIES: no data


COMPARISON WITH HISTORICAL CONTROL DATA: no data


ADDITIONAL INFORMATION ON CYTOTOXICITY: no data

The tester strains,are checked at regular intervals for their genetic markers, according to the methods of Ames et al. ( 4 ) :
1. Histidine-requirement
2. rfa-mutation: crystall violet sensitivity
3. uvrB-mutation: UV-sensitivity
4. R-factor: ampicillin resistance of the strains TA98 and TA100
All strains showed the expected criteria.

Mutation test

strain

Dose level (µg/plate)

Metabolic activation

Mean revertant colony counts

SD

TA98

0

-

22

4

50

-

18

4

100

-

21

5

500

-

17

1

1000

-

24

2

2500

-

23

6

5000

-

27

4

0

+

25

3

50

+

22

5

100

+

21

2

500

+

24

2

1000

+

33

4

2500

+

26

2

5000

+

24

1

TA100

0

-

128

18

50

-

140

6

100

-

131

5

500

-

151

11

1000

-

143

15

2500

-

133

10

5000

-

125

11

0

+

92

10

50

+

117

8

100

+

116

2

500

+

143

7

1000

+

147

15

2500

+

169

22

5000

+

144

5

TA1535

0

-

21

10

50

-

13

3

100

-

17

7

500

-

21

5

1000

-

18

4

2500

-

18

5

5000

-

20

2

0

+

14

6

50

+

14

3

100

+

11

5

500

+

15

3

1000

+

18

5

2500

+

16

6

5000

+

15

2

TA1537

0

-

7

3

50

-

7

4

100

-

8

2

500

-

8

5

1000

-

7

2

2500

-

10

2

5000

-

8

2

0

+

8

2

50

+

8

2

100

+

10

2

500

+

5

1

1000

+

6

3

2500

+

9

2

5000

+

6

2

TA1538

0

-

8

2

50

-

10

2

100

-

10

3

500

-

13

3

1000

-

14

4

2500

-

10

2

5000

-

12

4

0

+

13

2

50

+

11

4

100

+

8

2

500

+

9

4

1000

+

8

2

2500

+

8

3

5000

+

10

1

- Absence

+ Presence

SD Standard deviation

Positive control Mutation test 1:

Strain

Compound

Dose level (µg/plate)

Metabolic activation

Mean revertant colony counts

SD

TA98

2-nitrofluorene/2-aminoanthracene

5/1

-

296/21

61/2

TA100

2-nitrofluorene/2-aminoanthracene

5/1

-

628/153

22/23

TA1535

Sodium azide/2-aminoanthracene

1/1

-

282/15

13/7

TA1537

9-aminoacridine/2-aminoanthracene

50/1

-

104/10

11/3

TA1538

2-nitrofluorene/2-aminoanthracene

5/1

-

66/11

1/5

TA98

2-nitrofluorene/2-aminoanthracene

5/1

-

0/1021

0/139

TA100

2-nitrofluorene/2-aminoanthracene

5/1

+

0/1547

0/186

TA1535

Sodium azide/2-aminoanthracene

1/1

+

0/154

0/10

TA1537

9-aminoacridine/2-aminoanthracene

50/1

+

0/120

0/9

TA1538

2-nitrofluorene/2-aminoanthracene

5/1

+

0/508

0/37

Conclusions:
Interpretation of results (migrated information):
negative

Under the conditions of this Salmonella/Microsome assay the test material Ammoniumthiocyanate has no mutagenic effects.
Executive summary:

The test material Ammoniumthiocyanate was tested according to GLP and OECD471 in the Salmonella/ Microsome plate incorporation assay in the strains TA 98, TA 100, TA 1535, TA 1537 and TA 1538 in the absence and presence of metabolic activation. Under the conditions of this Salmonella/Microsome assay the test material Ammoniumthiocyanate has no mutagenic effects.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Additional information

Additional information from genetic toxicity in vitro:

Justification for read-across between ammonium, sodium and potassium thiocyanate is attached to chapter 13 “Assessment Reports - thiocyanates category justification document”. The three thiocyanate salts show comparable physical-chemical properties. Aqueous solutions of Thiocyanates salts of ammonium, sodium or potassium, are fully dissociated. Consequently, with no specific concerns for the kations (NH4+, Na+ and K+), are studies on one of the thiocyanate substances NH4SCN, NaSCN and KSCN fully applicable for the evaluation of the other substances.

 

Ammonium thiocyanate was negative in the Ames test. Sodium thiocyanate is negative in an in vitro chromosome aberration study and an in vitro mammalian mutagenicity study. All studies followed adequate OECD and EU protocols and were performed under GLP. Consequently, thiocyanates are considered to be non-genotoxic.


Justification for selection of genetic toxicity endpoint
For each endpoint bacterial mutagenicity, mammalian mutagenicity and mammalian clastogenicity a GLP compliant study is available.

Justification for classification or non-classification

Ammonium thiocyanate was negative in the Ames test. Sodium thiocyanate is negative in an in vitro chromosome aberration study and an in vitro mammalian mutagenicity study. Therefore classification is not warranted.