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Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

In vitro data from several gene mutation studies in bacteria (Ames Tests) on C8 -18 and C18 unsatd. AAPB, one in vitro gene mutation study in mammalian cells (L5178Y/ TK Mouse Lymphoma assay) performed on C8-18 AAPB and one cytogenicity study (in vivo Mammalian Erythrocyte Micronucleus Test) on C8 -18 and C18 unsatd. AAPB are available. All tests were consistently negative. There is no evidence for a genotoxic potential of AAPBs.

Link to relevant study records

Referenceopen allclose all

Endpoint:
in vitro gene mutation study in mammalian cells
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2009-10-21 to 2009-12-14
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)
Version / remarks:
1997
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)
Version / remarks:
2008
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of assay:
mammalian cell gene mutation assay
Target gene:
Thymidine Kinase Locus
Species / strain / cell type:
mouse lymphoma L5178Y cells
Details on mammalian cell type (if applicable):
- Type and identity of media: RPMI
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: yes
- Periodically "cleansed" against high spontaneous background: yes
Additional strain / cell type characteristics:
other: Clone 3.7.2C
Metabolic activation:
with and without
Metabolic activation system:
Rat liver S9
Test concentrations with justification for top dose:
Pre-Experiment: 39.1; 78.1; 156.3; 312.5; 625; 1250; 2500; 5000 µg/mL

Experiment I:
without S9 mix (4 hours treatment): 2.4; 4.9; 9.8; 19.5; 39.0; 58.5; 78.0 µg/mL; evaluated: 2.4; 4.9; 9.8; 39 µg/mL
with S9 mix (4 hours treatment): 4.9; 9.8; 19.5; 39.0; 78.0; 117.0; 156.0 µg/mL; evaluated: 4.9; 9.8; 19.5; 39.0; 78.0 µg/mL

Experiment II:
without metabolic activation (24 hours treatment): 2.5; 5.0; 10.0; 20.0; 40.0; 50.0; 60.0 µg/mL; evaluated: 10; 20; 40; 50; 60 µg/mL
with metabolic activation (4 hours treatment): 10.0; 20.0; 40.0; 80.0; 100.0; 110.0; 120.0 µg/mL; evaluated: 40, 80, 100, 110, 120 µg/mL



Vehicle / solvent:
- Vehicle(s)/solvent(s) used: deionised water (10 %)
- Justification for choice of solvent/vehicle: solubility properties
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
deionised water
True negative controls:
no
Positive controls:
yes
Positive control substance:
methylmethanesulfonate
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
deionised water
True negative controls:
no
Positive controls:
yes
Positive control substance:
cyclophosphamide
Details on test system and experimental conditions:
METHOD OF APPLICATION:

DURATION
- Exposure duration: Experiment I: 4 hours with and without metabolic activation
Experiment II: 24 hours without metabolic activation, 4 hours with metabolic activation
- Expression time (cells in growth medium): 48 hours
- Selection time (if incubation with a selection agent): 10 to 15 days

SELECTION AGENT (mutation assays): RPMI 1640 medium by addition of 5 µg/mL TFT (Trifluorothymidine)

NUMBER OF REPLICATIONS: 2

NUMBER OF CELLS EVALUATED: approx. 4000 cells per well

DETERMINATION OF CYTOTOXICITY
- Method: relative total growth


Evaluation criteria:
A test item is classified as mutagenic if the induced mutation frequency reproducibly exceeds a threshold of 126 colonies per 1E6 cells above the corresponding solvent control.
A relevant increase of the mutation frequency should be dose-dependent.
A mutagenic response is considered to be reproducible if it occurs in both parallel cultures.
However, in the evaluation of the test results the historical variability of the mutation rates in the solvent controls of this study are taken into consideration.
Results of test groups are generally rejected if the relative total growth is less than 10 % of the vehicle control unless the exception criteria specified by the IWGT recommendations are fulfilled.
Whenever a test item is considered mutagenic according to the above mentioned criteria, the ratio of small versus large colonies is used to differentiate point mutations from clastogenic effects. If the increase of the mutation frequency is accompanied by a reproducible and dose dependent shift in the ratio of small versus large colonies clastogenic effects are indicated.
Statistics:
Linear regression analysis (least squares) using SYSTAT11 (SYSTAT Software, Inc., 501, Canal Boulevard, Suite C, Richmond, CA 94804, USA)
Key result
Species / strain:
mouse lymphoma L5178Y cells
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: not effected
- Effects of osmolality: not increased
- Precipitation: No
- Other confounding effects: None

RANGE-FINDING/SCREENING STUDIES:
The highest concentration used in the pre-test was chosen with regard to the solubility of the test item in deionised water. Test item concentrations between 39.1 and 5000 µg/mL were used to evaluate toxicity in the presence (4 h treatment) and absence (4 h and 24 h treatment) of metabolic activation.
Strong toxic effects were observed at 78.1 µg/mL and above in the absence of metabolic activation (4 h treatment) and at 312.5 µg/mL and above in the presence of metabolic activation. Following continuous treatment (24 hours) toxic effects as described above occurred already at the lowest concentration of 39.1 µg/mL and above.
The test medium was checked for precipitation at the end of each treatment period (4 or 24 hours) before the test item was removed. No precipitation occurred up to the maximum concentration with and without metabolic activation at both treatment intervals.
The dose range of the main experiments was limited by toxicity of the test item. The individual concentrations were generally spaced by a factor of 2.0. A closer spacing was used in the upper concentration range to cover toxic effects more closely. A very narrow dose spacing was used in the second experiment with and without metabolic activation to cover the recommended cytotoxic range of approximately 10-20% relative total growth.

COMPARISON WITH HISTORICAL CONTROL DATA:
In experiment II the mutant frequency exceeded the range of the historical solvent control data at several test points without metabolic activation (both cultures) and at one test point with metabolic activation (culture I). However, the threshold described above was not reached at any test point of the second experiment and no dose dependent increase was indicated by statistical analysis.


ADDITIONAL INFORMATION ON CYTOTOXICITY:
Relevant cytotoxic effects indicated by a relative total growth of less than 50 % in both parallel cultures were observed in the absence of metabolic activation at 39 µg/mL in experiment I following 4 hour treatment and at 40 µg/mL and above in experiment II following 24 hours treatment. In the presence of metabolic activation toxic effects as described above occurred at 100 µg/mL and above in experiment II. No reproducible cytotoxic effects were noted in the first experiment with metabolic activation. The recommended toxic range of approximately 10-20 % RTG was covered in the second experiment with and without metabolic activation.
The isolated minor reduction of the relative total growth to 43.5 % in the first culture of experiment I with metabolic activation was not considered a real toxic effect since no comparable reduction was observed in the parallel culture under identical conditions.
Summary Table
      relative mutant   relative mutant  
  conc. µg S9 total colonies/   total colonies/  
  per mL mix growth 106cells threshold growth 106cells threshold
Column 1 2 3 4 5 6 7 8
Experiment I / 4 h treatment     culture I culture II
Solv. control with water - 100.0 147 273 100.0 141 267
Pos. control with MMS  19.5 -  32.4 424 273  23.7 403 267
Test item   2.4 - 131.7 122 273  67.5 209 267
Test item   4.9 - 122.7 134 273 129.3 139 267
Test item   9.8 - 103.9 137 273 126.0 104 267
Test item  19.5 -  43.7 275 273  96.9  96 267
Test item  39.0 -  31.1 187 273  39.3 181 267
Test item  58.5 - culture was not continued# culture was not continued#
Test item  78.0 - culture was not continued# culture was not continued#
       
Solv. control with water + 100.0 130 256 100.0 141 267
Pos. control with CPA   3.0 +  61.5 232 256  90.0 250 267
Pos. control with CPA   4.5  +   44.8 320 256  54.6 348 267
Test item   4.9  +   66.2 164 256 137.6  99 267
Test item   9.8  +  104.3 140 256 134.1 146 267
Test item  19.5  +   57.7 202 256 125.6 134 267
Test item  39.0  +  111.4 105 256 147.5  83 267
Test item  78.0  +   43.5 149 256 108.2 154 267
Test item  117.0  +  culture was not continued# culture was not continued#
Test item  156.0  +  culture was not continued# culture was not continued#
Experiment II / 24 h treatment     culture I culture II
Solv. control with water - 100.0 158 284 100.0 153 279
Pos. control with MMS  13.0 -  19.2 569 284  25.0 573 279
Test item   2.5 - culture was not continued## culture was not continued##
Test item

  5.0

- culture was not continued## culture was not continued##
Test item  10.0 -  65.9 217 284  78.7 264 279
Test item  20.0 -  44.3 208 284  71.1 230 279
Test item  40.0 -  33.1 173 284  45.8 208 279
Test item  50.0 -  38.5 182 284  29.8 214 279
Test item  60.0 -  20.7 209 284  16.2 241 279
Experiment II / 4 h treatment     culture I culture II
Solv. control with water + 100.0 164 290 100.0 145 271
Pos. control with CPA   3.0 +  52.2 355 290  25.0 312 271
Pos. control with CPA   4.5 +  23.6 385 290  23.3 407 271
Test item  10.0 + culture was not continued## culture was not continued##
Test item  20.0 + culture was not continued## culture was not continued##
Test item  40.0 +  75.5 171 290 102.9 189 271
Test item  80.0 +  40.2 210 290  61.6 159 271
Test item  100.0 +  47.1 133 290  49.0 149 271
Test item  110.0 +  32.6 183 290  42.0 167 271
Test item  120.0 +  22.0 203 290  29.0 201 271

Threshold = number of mutant colonies per 106cells of each solvent control plus 126

#      culture was not continued due to exceedingly severe cytotoxic effects
##
    culture was not continued since a minimum of only four analysable concentrations is required

Conclusions:
The test item did not induce mutations in the mouse lymphoma thymidine kinase locus assay using the cell line L5178Y in the absence and presence of metabolic activation.
Executive summary:

The study was performed to investigate the potential of C8 -18 AAPB to induce mutations at the mouse lymphoma thymidine kinase locus using the cell line L5178Y.

The assay was performed in two independent experiments, using two parallel cultures each. The first main experiment was performed with and without liver microsomal activation and a treatment period of 4 h. The second experiment was performed with a treatment period of 24 hours in the absence and 4 hours in the presence of metabolic activation.

The main experiments were evaluated at the following concentrations:

Experiment I:

without S9 mix:                     2.4; 4.9; 9.8; 19.5; and 39.0 µg/mL
with S9 mix:                         4.9; 9.8; 19.5; 39.0; and 78.0 µg/mL

Experiment II:

without S9 mix:                                10; 20; 40; 50; and 60 µg/mL

with S9 mix:                               40; 80; 100; 110; and 120 µg/mL

Relevant cytotoxic effects indicated by a relative total growth of less than 50 % in both parallel cultures were observed in the absence of metabolic activation at 39 µg/mL in experiment I following 4 hour treatment and at 40 µg/mL and above in experiment II following 24 hours treatment. In the presence of metabolic activation toxic effects as described above occurred at 100 µg/mL and above in experiment II. No reproducible cytotoxic effects were noted in the first experiment with metabolic activation. The recommended toxic range of approximately 10-20 % RTG was covered in the second experiment with and without metabolic activation.

The isolated minor reduction of the relative total growth to 43.5 % in the first culture of experiment I with metabolic activation was not considered a real toxic effect since no comparable reduction was observed in the parallel culture under identical conditions.

No substantial and reproducible dose dependent increase of the mutation frequency was observed with and without metabolic activation. The mutation frequency did not reproducibly reach or exceed the threshold of 126 above the mutation frequency of the corresponding solvent control in any of the experimental parts. An isolated increase exceeding the threshold was noted in the first culture of experiment I without metabolic activation at 19.5 µg/mL. However, this increase was judged as irrelevant fluctuation since it was not reproduced in the parallel culture under identical experimental conditions. Furthermore, the increase was not dose dependent as indicated by the lacking statistical significance. In experiment II the mutant frequency exceeded the range of the historical solvent control data at several test points without metabolic activation (both cultures) and at one test point with metabolic activation (culture I). However, the threshold described above was not reached at any test point of the second experiment and no dose dependent increase was indicated by statistical analysis.

A linear regression analysis (least squares) was performed to assess a possible dose dependent increase of mutant frequencies using SYSTATâ11statistics software. No significant dose dependent trend of the mutation frequency indicated by a probability value of <0.05 was determined in all experimental groups.

In this study the range of the solvent controls was from 130 up to 164 mutant colonies per 1E6 cells; the range of the groups treated with the test item was from 83 up to 275 mutant colonies per 1E6 cells. The solvent controls remained within the range of the historical data.

Methylmethanesulfonate (19.5 µg/mL in experiment I and 13.0 µg/mL in experiment II) and cyclophosphamide (3.0 µg/mL and 4.5 µg/mL in both main experiments) were used as positive controls and showed a distinct increase in induced total mutant colonies at acceptable levels of toxicity with at at least one of the concentrations of the controls.

There was no concentration related positive response of induced mutant colonies over background.

This study is classified as acceptable. This study satisfies the requirement for Test Guidelines Ninth Addendum to the OECD Guidelines for the Testing of Chemicals, February 1998, adopted July 21, 1997, Guideline No. 476 "In vitro Mammalian Cell Gene Mutation Test“ and Commission Regulation (EC) No. 440/2008 B.17: ”Mutagenicity –In vitro Mammalian Cell Gene Mutation Test“, dated May 30, 2008 for in vitro mutagenicity (mammalian forward gene mutation) data.

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
see "General Justification for Read-Across" attached to IUCLID section 13

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Mutual read across from the AAPBs to one another is justified:

a) Based on the information given in section 1, it can be concluded that all AAPBs mentioned above are similar in structure, since they are manufactured from similar resp. identical precursors under similar conditions and all contain the same functional groups. Thus a common mode of action can be assumed.
b) The content of minor constituents in all products are comparable and differ to an irrelevant amount.
c) The only deviation within this group of substances is a minor variety in their fatty acid moiety, which is not expected to have a relevant impact on intrinsic toxic or ecotoxic activity and environmental fate. Potential minor impact on specific endpoints will be discussed in the specific endpoint sections.

The read-across hypothesis is based on structural similarity of target and source substances. Based on the available experimental data, including key physico-chemical properties and data from toxicokinetic, acute toxicity, irritation, sensitisation, genotoxicity and repeated dose toxicity studies, the read-across strategy is supported by a quite similar toxicological profile of all five substances.
The respective data are summarised in the data matrix; robust study summaries are included in the Technical Dossier in the respective sections.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
see "General Justification for Read-Across" attached to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
see "General Justification for Read-Across" attached to IUCLID section 13

4. DATA MATRIX
see "General Justification for Read-Across" attached to IUCLID section 13
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across: supporting information
Key result
Species / strain:
other: S. typhimurium TA 1535, TA 100, TA 1537, TA 1538 and 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
Conclusions:
negative with and without metabolic activation
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

A cytogenicity study (in vivo Mammalian Erythrocyte Micronucleus Test) on C8 -18 and C18 unsatd. AAPB is available, which showed no genotoxic potential.

Link to relevant study records
Reference
Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
see "General Justification for Read-Across" attached to IUCLID section 13

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Mutual read across from the AAPBs to one another is justified:

a) Based on the information given in section 1, it can be concluded that all AAPBs mentioned above are similar in structure, since they are manufactured from similar resp. identical precursors under similar conditions and all contain the same functional groups. Thus a common mode of action can be assumed.
b) The content of minor constituents in all products are comparable and differ to an irrelevant amount.
c) The only deviation within this group of substances is a minor variety in their fatty acid moiety, which is not expected to have a relevant impact on intrinsic toxic or ecotoxic activity and environmental fate. Potential minor impact on specific endpoints will be discussed in the specific endpoint sections.

The read-across hypothesis is based on structural similarity of target and source substances. Based on the available experimental data, including key physico-chemical properties and data from toxicokinetic, acute toxicity, irritation, sensitisation, genotoxicity and repeated dose toxicity studies, the read-across strategy is supported by a quite similar toxicological profile of all five substances.
The respective data are summarised in the data matrix; robust study summaries are included in the Technical Dossier in the respective sections.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
see "General Justification for Read-Across" attached to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
see "General Justification for Read-Across" attached to IUCLID section 13

4. DATA MATRIX
see "General Justification for Read-Across" attached to IUCLID section 13
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across: supporting information
Key result
Sex:
male/female
Genotoxicity:
negative
Toxicity:
yes
Remarks:
in preliminary dose finding study lethal at doses >/= 1000 mg/kg bw
Vehicle controls validity:
valid
Positive controls validity:
valid
Conclusions:
The test substance did not induce clastogenic effects in this in vivo cytogenicity study on mice at dose levels of 20 and 200 mg/kg bw/day.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Additional information

For the target substance C8-18 AAPB, an in vitro gene mutation study in mammalian cells (L5178Y/ TK Mouse Lymphoma assay) is available. Moreover, reliable, relevant and adequate data on the genetic toxicity of AAPBs is available from several in vitro gene mutation studies in bacteria (Ames Tests), and one in vivo cytogenicity study (in vivo Mammalian Erythrocyte Micronucleus Test), all conducted with the closely related substance C8-18 and C18 unsatd. AAPB.

All tests were consistently negative. There is no evidence for a genotoxic potential of AAPBs.

A justification for read-across is given below.

 

In vitro data

In the key in vitro reverse gene mutation assay in bacteria performed according to EU Method B.14 (Version Commission Directive 92/69/EEC), strains TA 1535, TA 1537, TA 1538, TA 98 and TA 100 ofSalmonella typhimuriumwere exposed to C8-18 and C18 unsatd. AAPB. Test was performed with concentrations up to and including cytotoxic concentrations in the absence and the presence of mammalian metabolic activation.

No evidence of biologically significant mutagenic activity of the test item was found in the presence and absence of metabolic activation, up to and including its cytotoxic limit. The positive controls induced the appropriate responses in the corresponding strains and activity of metabolizing system was confirmed.

There was no evidence of induced mutant colonies over background.

The adopted OECD TG 471 (1997) requires at least 5 test strains and the use of E. coli WP2 strains or Salmonella typhimurium TA 102 to detect certain oxidizing mutagens, cross-linking agents and hydrazines. However, AAPB is not a highly reactive agent and is therefore not expected to be a cross-linking agent, has no oxidizing properties and is no hydrazine. Thus, a GLP test according to former versions of OECD TG 471 and EU Method B.13/14 (Version Commission Directive 92/69/EEC) without E. coli WP2 strains or Salmonella typhimurium TA 102 is considered as sufficient to evaluate the mutagenic activity of AAPB in this bacterial test system.

Consistently negative results were also seen in several further supporting in vitro gene mutation assays in bacteria performed on Coco AAPB.

 

In a mammalian cell gene mutation assay according to OECD Guideline 476 (1997) and EU Method B.17 (2008), the potential of C8 -18 AAPB to induce mutations at the mouse lymphoma thymidine kinase locus using the cell line L5178Y was tested.

The assay was performed in two independent experiments, using two parallel cultures each. The first main experiment was performed with and without liver microsomal activation and a treatment period of 4 h. The second experiment was performed with a treatment period of 24 hours in the absence and 4 hours in the presence of metabolic activation.

The main experiments were evaluated at the following concentrations:

Experiment I:

without S9 mix: 2.4; 4.9; 9.8; 19.5; and 39.0 µg/mL

with S9 mix: 4.9; 9.8; 19.5; 39.0; and 78.0 µg/mL

Experiment II:

without S9 mix: 10; 20; 40; 50; and 60 µg/mL

with S9 mix: 40: 80; 100; 110; and 120 µg/mL

Relevant cytotoxic effects indicated by a relative total growth of less than 50% in both parallel cultures were observed in the absence of metabolic activation at 39 µg/mL in experiment I following 4 hour treatment and at 40 µg/mL and above in experiment II following 24 hours treatment. In the presence of metabolic activation toxic effects as described above occurred at 100 µg/mL and above in experiment II. No reproducible cytotoxic effects were noted in the first experiment with metabolic activation. The recommended toxic range of approximately 10-20 % relative total growth was covered in the second experiment with and without metabolic activation.

The isolated minor reduction of the relative total growth to 43.5% in the first culture of experiment I with metabolic activation was not considered a real toxic effect since no comparable reduction was observed in the parallel culture under identical conditions.

No substantial and reproducible dose dependent increase of the mutation frequency was observed with and without metabolic activation. The mutation frequency did not reproducibly reach or exceed the threshold of 126 above the mutation frequency of the corresponding solvent control in any of the experimental parts. An isolated increase exceeding the threshold was noted in the first culture of experiment I without metabolic activation at 19.5 µg/mL. However, this increase was judged as irrelevant fluctuation since it was not reproduced in the parallel culture under identical experimental conditions. Furthermore, the increase was not dose dependent as indicated by the lacking statistical significance. In experiment II the mutant frequency exceeded the range of the historical solvent control data at several test points without metabolic activation (both cultures) and at one test point with metabolic activation (culture I). However, the threshold described above was not reached at any test point of the second experiment and no dose dependent increase was indicated by statistical analysis.

A linear regression analysis (least squares) was performed to assess a possible dose dependent increase of mutant frequencies using SYSTAT11statistics software. No significant dose dependent trend of the mutation frequency indicated by a probability value of <0.05 was determined in all experimental groups. In this study the range of the solvent controls was from 130 up to 164 mutant colonies per 106cells; the range of the groups treated with the test item was from 83 up to 275 mutant colonies per 106cells. The solvent controls remained within the range of the historical data. Methylmethanesulfonate (19.5 µg/mL in experiment I and 13.0 µg/mL in experiment II) and cyclophosphamide (3.0 µg/mL and 4.5 µg/mL in both main experiments) were used as positive controls and showed a distinct increase in induced total mutant colonies at acceptable levels of toxicity with at least one of the concentrations of the controls.

There was no concentration related positive response of induced mutant colonies over background.

 

In vivo data

The cytogenetic activity of the AAPBs was tested in a OF1 (I. O. P. S. Caw) mouse bone marrow micronucleus assay, performed as described by W. Schmid - The Micronucleus test, Mutation Research, 31, 9-15 (1975). 5 male and 5 female animals were treated i. p. with Coco AAPB (30 % a. i). The test method by W. Schmidt is almost equivalent to the procedure described by OECD guideline 474. In a preliminary study the test animals were administered twice (in a 24 hours interval) each 100, 200, 500, 1000 and 2000 mg/kg bw/day by intraperitoneal injection. Clinical signs and mortality were observed up to 30 hours after the first administration. Clinical signs like piloerection and ptosis were seen at doses of ≥ 100 mg/kg bw/day. At doses ≥ 1000 mg/kg bw/day the mice died within 30 and 4 hours after the first administration. The tolerated doses were in the range of 100 to 500 mg/kg bw/day. Therefore, the dose of 200 mg/kg bw/day was selected as the high dose and 20 mg/kg bw/day (10 % of the high dose) as the low dose. As the test substance was applied twice with a 24 h interval (although only one timepoint was chosen for sacrifice), the result of the sacrifice 6h later may be regarded as a result of a 30h and a 6h treatment. The dose level of 200 mg/kg bw/day (corresponding to 60 mg active substance/kg bw/day) is considered to be sufficiently high based on the effects found in the preliminary study and due to the highly irritating properties of the compound.

The mean number of micronucleated erythrocytes/1000 polychromatic erythrocytes in males and female mice at 20 and 200 mg/kg bw/day were unaffected compared to the negative controls. The administration of 100 mg cyclophosphamide/kg bw serving as the positive control led to clearly elevated numbers of micronucleated erythrocytes.

It can be concluded, that Coco AAPB (30 % a. i) induced no clastogenic effect in this in vivo cytogenicity study on mice at dose levels of 20 and 200 mg/kg bw/day.

 

Conclusion

Reliable, relevant and adequate data on the genetic toxicity of AAPBs is available from several in vitro gene mutation studies in bacteria (Ames Tests), one in vitro gene mutation study in mammalian cells (L5178Y/ TK Mouse Lymphoma assay) and one in vivo cytogenicity study (in vivo Mammalian Erythrocyte Micronucleus Test). The full set of mutagenicity tests required by REACH Regulation Annexes VII and VIII is covered with the studies, whereas the information requirement on an in vitro cytogenicity study in mammalian cells or in vitro micronucleus study is fulfilled in accordance to Annex VIII, column 2 by adequate data from an in vivo cytogenicity study. The studies were performed on Coco AAPB or C8-18 AAPB.

There was no evidence of mutagenic or clastogenic intrinsic properties in any of the performed studies.

The genotoxic potential of the whole group of AAPBs is assumed to be similar. As fatty acids independently from their chain length and degree on unsaturation are generally considered to be not genotoxic, a variability in the fatty acid moiety is not expected to have any influence on the genotoxic activity of the AAPBs. Thus, the use of studies performed on individual members of this group of substances as read-across for the whole group is justified without restrictions.

In conclusion there is no evidence for genotoxic properties for C12 AAPB.

 

There are no data gaps for the endpoint genotoxicity. No human information is available for this endpoint. However, there is no reason to believe that these results would not be applicable to humans.

 

Justification for read-across

For details on substance identity and detailed toxicological profiles, please refer also to the general justification for read-across given at the beginning of the CSR and attached as pdf document to IUCLID section 13.

This read-across approach is justified based on structural similarities. All AAPBs contain the same functional groups. Thus a common mode of action can be assumed.

The only deviation within this group of substances is a minor variety in their fatty acid moiety (chain length and degree of unsaturation), which may have an influence on the outcome of skin and eye irritation studies, but is not expected to have any influence on genotoxic properties.

 

a. Structural similarity and functional groups

Alkylamidopropyl betaines (AAPBs) are – with the exception of C12 AAPB - UVCB substances (Substances of Unknown or Variable composition, Complex reaction products or Biological materials), which are defined as reaction products of natural fatty acids or oils with dimethylaminopropylamine and further reaction with sodium monochloroacetate. AAPBs are amphoteric surfactants, which are characterized by both acidic and alkaline properties.

 

Their general structure is:

 

R-C(O)-NH-(CH2)3-(N(CH3)2)+-CH2-C(O)O-

R = fatty acid moiety

 

The fatty acids have a mixed, slightly varying composition with an even numbered chain length from C8 to C18. Unsaturated C18 may be included. Consequently, the AAPBs differ by their carbon chain length distribution and the degree of unsaturation in the fatty acid moiety. However, Lauramidopropyl betaine (C12 fatty acid derivate) is the major ingredient of all AAPBs covered by this justification as listed in table 1 “Substance identities” of the general justification for read-across.

 

The substances under evaluation share structural similarities with common functional groups (quaternary amines, amide bonds and carboxymethyl groups), and fatty acid chains with differences in chain length and degree of saturation. As fatty acids independently from their chain length and degree on unsaturation are generally considered to be not genotoxic, a variability in the fatty acid moiety is not expected to have any influence on the genotoxic activity of the AAPBs.

 

b. Differences

Differences in the genetic toxicity potential of the AAPBs could potentially arise from the following facts:

-Different amounts of different carbon chain lengths (carbon chain length distribution):

Higher amounts of higher chain lengths and corresponding lower amounts of lower chain length could result in a rising average lipophilicity. As fatty acids independently from their chain length are generally considered to be not genotoxic, a variability in the fatty acid moiety is not expected to have any influence on the genotoxic activity of the AAPBs

- Different amounts of unsaturated fatty ester moieties:

Effects may be expected for e.g. physical state and for some toxicological endpoints, mainly local effects (e.g. irritation). However, as fatty acids independently from their degree on unsaturation are generally considered to be not genotoxic, a variability in the fatty acid moiety is not expected to have any influence on the genotoxic activity of the AAPBs.

 

Comparison of genotoxicity data

 

Endpoints

Source substance

Target substance

 

C8-18 and C18 unsatd. AAPB

C8-18 AAPB

Genotoxicity in vitro

Gene mutation in bacteria

key_Genetic toxicity in vitro: 147170-44-3_8.4.1_Zschimmer_1996_EEC 92_69

 

key study

 

EU Method B.13/14, gene mutation: bacterial reverse mutation assay (e.g. Ames test),

S. typhimurium TA 1535, TA 100, TA 1537, TA 1538 and TA 98

Metabolic activation: with and without

cytotoxicity: first evidence of toxicity at 10000 µg/plate with and without S9

 

Genotoxicity: negative

 

Reliability: 2 (reliable with restrictions), no GLP

No data, read-across

Sup_Genetic toxicity in vitro: 61789-40-0_8.4.1_Hüls_1995_OECD 471

 

Supporting study

 

OECD TG 471, gene mutation: bacterial reverse mutation assay (e.g. Ames test)

Metabolic activation: with and without

cytotoxicity: >= 1000 µg/plate (TA 1535, 1537), 5000 µg/plate (TA98)

 

Genotoxicity: negative

 

Reliability: 1 (reliable without restriction), yes

Sup_Genetic toxicity in vitro: 61789-40-0_8.4.1_Henkel_1988_OECD 471

 

Supporting study

 

OECD TG 471, gene mutation: bacterial reverse mutation assay (e.g. Ames test)

Metabolic activation: with and without

cytotoxicity: >= 256 µg/plate

 

Genotoxicity negative

 

Reliability: 1 (reliable without restriction), GLP

Sup_Genetic toxicity in vitro: 61789-40-0_8.4.1_REWO_1987_OECD 471_neuscan

 

Supporting study

 

OECD TG 471, gene mutation: bacterial reverse mutation assay (e.g. Ames test)

S. typhimurium TA 100, TA 1535, TA 98, TA 1538, TA 1537

Metabolic activation: with and without

cytotoxicity: no (3.12 µl/plate no colonies on the plates detected)

 

Genotoxicity negative

 

Reliability: 1 (reliable without restriction), GLP

Sup_Genetic toxicity in vitro: 61789-40-0_8.4.1_THG_1982

 

Supporting study

 

similar to OECD TG 471, gene mutation: bacterial reverse mutation assay (e.g. Ames test)

S. typhimurium TA 1535, TA 1537, TA 1538, TA 98, TA 100

Metabolic activation: with and without

cytotoxicity: not determined

 

Genotoxicity: negative

 

Reliability: 2 (reliable with restrictions), no GLP

Gene mutation in mammalian cells

No data

Key_Genetic toxicity in vitro: 97862-59-4_8.4.3_MoLy_Evonik_2010_OECD-476

key study

OECD TG 476,gene mutation: mammalian cell gene mutation assay, 
mouse lymphoma L5178Y cells Metabolic activation: with and without

cytotoxicity: yes

 

Genotoxicity: negative

 

Reliability: 1 (reliable without restriction), GLP

Genotoxicity in vivo

Key_Genetic toxicity in vivo: 61789-40-0_8.4.4_Goldschmidt_France_1987_micronucleus test in vivo
Study result type: experimental result

similar to OECD Guideline TG 474,chromosome aberration: micronucleus assay, mouse, intraperitoneal,100 mg/kg bw

 

toxicity: yes (in preliminary dose finding study lethal at doses >/= 1000 mg/kg bw);

vehicle controls valid: yes;

positive controls valid: yes


Genotoxicity negative

 

Reliability: 2 (reliable with restrictions), GLP

No data, read-across

 

In a mammalian cell gene mutation assay according to OECD Guideline 476 the target substance C8-18 AAPB induced no concentration related positive response of induced mutant colonies over background when tested up to cytotoxic concentrations.

The source substance C8-18 and C18 unsatd. AAPB was not mutagenic in several reverse gene mutation assays in bacteria (Ames test).

The source substance C8-18 and C18 unsatd. AAPB was not clastogenic in a mouse bone marrow micronucleus assay.

 

Quality of the experimental data of the analogues:

The available data are adequate and sufficiently reliable to justify the read-across approach.

The key studies were conducted according to EU Method B.13/14, OECD Guideline 476 or similar to OECD Guideline 474 and were reliable or reliable with restrictions (RL1-2).

Several supporting studies (RL1-2) are available, which were conducted according to (or comparable to) OECD Guideline 471.

The test materials used in the respective studies represent the source substance as described in the hypothesis in terms of substance identity and minor constituents.

Overall, the study results are adequate for the purpose of classification and labelling and risk assessment.

 

Conclusion

Based on structural similarities of the target and the source substanceas presented above and in more detail in the general justification for read across, it can be concluded that the available data from the source substance C8-18 and C18 unsatd. AAPB are also valid for the target substance C8-18 AAPB.

As fatty acids independently from their chain length and degree on unsaturation are generally considered to be not genotoxic, a variability in the fatty acid moiety is not expected to have any influence on the genotoxic activity of the AAPBs. Thus, the use of studies performed on individual members of this group of substances as read-across for the whole group is justified without restrictions.

There was no evidence of mutagenic or clastogenic intrinsic properties in any of the performed studies.

Justification for classification or non-classification

AAPBs considered to have no genotoxic properties as shown in several gene mutation studies in bacteria (Ames Tests), one in vitro gene mutation study in mammalian cells (L5178Y/ TK Mouse Lymphoma assay) and one in vivo cytogenicity study (in vivo Mammalian Erythrocyte Micronucleus Test).

Therefore, AAPBs do not comply with the classification requirements regarding germ cell mutagenicity outlined in regulation (EC) 1272/2008 or the former European directive on classification and labelling 67/548/EEC.