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Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in mammalian cells
Remarks:
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1990
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
Study performed similarly to OECD Guideline 476 with minor deviations: no data on maintenance of cell cultures and absence of mycoplasma
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1990

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)
Deviations:
yes
Remarks:
no data on maintenance of cell cultures and absence of mycoplasma
Principles of method if other than guideline:
Not applicable
GLP compliance:
not specified
Type of assay:
mammalian cell gene mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid

Method

Target gene:
Thymidine kinase, TK +/- locus
Species / strain
Species / strain / cell type:
mouse lymphoma L5178Y cells
Details on mammalian cell type (if applicable):
- Source of cells: National Toxicology Program's (NTP) chemical repository (Radian Corporation, Austin, USA)
- Type and identity of media: Fischer’s medium used for expression and cloning; horse serum used at 20% v/v for soft agar cloning
Additional strain / cell type characteristics:
not specified
Metabolic activation:
with and without
Metabolic activation system:
S9 fraction of male Fischer 344 rat liver induced with Aroclor-1254
Test concentrations with justification for top dose:
Without S9:
- Trail 1: 0, 10, 20, 30, 40, 50 and 60 nL/mL
- Trail 2: 0, 30, 40, 50, 60, 80 and 100 nL/mL
- Trail 3: 0, 5, 10, 20, 30, 40 and 50 nL/mL
- Trail 4: 0, 5, 10, 20, 30, 40, 50 and 60 nL/mL

With S9:
- Trail 1: 0, 10, 20, 30, 40, 50, 60 and 80 nL/mL
- Trail 2: 0, 10, 20, 30, 40, 50, 60 and 80 nL/mL
- Trail 3: 0, 30, 40, 50, 60, 80 and 100 nL/mL
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: 1% ethanol
Controlsopen allclose all
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
1% ethanol
True negative controls:
no
Positive controls:
yes
Positive control substance:
methylmethanesulfonate
Remarks:
without metabolic activation Migrated to IUCLID6: 5 nL/mL
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
1% ethanol
True negative controls:
no
Positive controls:
yes
Positive control substance:
3-methylcholanthrene
Remarks:
with metabolic activation Migrated to IUCLID6: 2.5 µg/mL
Details on test system and experimental conditions:
METHOD OF APPLICATION: In medium

DURATION
- Exposure duration: 4 hours at 37 °C
- Expression time (cells in growth medium): 48 hours at 37 °C
- Selection time (if incubation with a selection agent): 9-12 days at 37 °C

SELECTION AGENT (mutation assays): Trifluorothymidine (TFT)

NUMBER OF REPLICATIONS: Duplicate (at least)

NUMBER OF CELLS EVALUATED: 6 x 10^6 cells exposed to the test item, 3 x 10^6 cells to select mutant cells; 600 cells to determine cloning efficiency

DETERMINATION OF CYTOTOXICITY
- Method: Relative growth on Days 1 and 2, cloning efficiency and relative total growth

OTHER EXAMINATIONS:
- Colony sizing: Number of small and large mutant colonies were determined by recording TFT colony counts for increments of 0.2 on the colony size discriminator.

OTHER: Colonies were counted on an Artek 880 colony counter fitted with a 10-turn size discriminator.
Evaluation criteria:
Positive (+):
- Significant response for at least one of the three highest dose sets and a significant trend (P ≤ 0.05)

Questionable (?):
- Significant response for one of the three highest dose sets but no significant trend
- Significant trend but no significant dose set

Inconclusive (i):
- Significant response for a dose set other than one of the three highest but no significant trend
- No significant responses or trend, but the relative total growth is greater than 30% and higher toxicity can be attained

No response (=):
- No significant responses or trend, and the relative total growth is greater than 30% under conditions where a 1.5-fold increase in dose cause precipitation or where the 5 mg/mL (or 5 µL/mL) concentration limit is attained.

Negative (-):
- No significant responses or trend, and either the relative total growth is less than 30% or excessive toxicity occurs for a 1.5-fold higher dose.
Statistics:
Consistency among the mutant frequencies was analysed using chi-square test; acceptable cultures must be significant at P ≤ 0.05

Results and discussion

Test results
Key result
Species / strain:
mouse lymphoma L5178Y cells
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at or above 50 and 60 nL/mL (with and without S9, respectively)
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
Response in trials without S9:
- Trail 1: Inconclusive (i)
- Trail 2: Questionable (?)
- Trail 3 and 4: Negative (-)
- Overall response: Negative (-)

Response in trials with S9:
- Trail 1 and 2: Negative (-)
- Trail 3: Inconclusive (i)
- Overall response: Negative (-)


ADDITIONAL INFORMATION ON CYTOTOXICITY:
- Without S9: Cytotoxicity was observed in one or more replicates tested at concentration of 50 nL/mL or above
- With S9: Cytotoxicity was observed in one or more replicates tested at concentration of 60 nL/mL or above
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

Table 1: Chemical-induced changes in the large and small classes of mutant colonies

 

Chemical treatment

Trial

Mutant colony count and CE

Mutant frequency

Mutant frequency change

Treatment

Solvent control

Treatment

Solvent control

Difference

L

S

CE

L

S

CE

L

S

L

S

L

S

50 nL/mL

WO 2

48

119

98

44

53

85

16

40

17

21

-1

19

50 nL/mL

S9 2

98

143

79

72

109

115

41

60

21

32

20

28

Applicant's summary and conclusion

Conclusions:
d-Limonene was not considered as mutagenic in mouse lymphoma L5178Y cells and does not need to be classified according to Directive 67/548/EEC and CLP Regulation (EC) No 1272/2008.
Executive summary:

In an in vitro mammalian cell gene mutation test performed similarly to OECD Guideline 476, mouse lymphoma L5178Y TK+/- cells were exposed to d-limonene in 1% ethanol in Fischer’s medium with and without metabolic activation (S9 fraction of male Fischer 344 rat liver induced with Aroclor-1254) at the concentrations below

Without S9:

- 0, 10, 20, 30, 40, 50 and 60 nL/mL (trial 1)

- 0, 30, 40, 50, 60, 80 and 100 nL/mL (trial 2)

- 0, 5, 10, 20, 30, 40 and 50 nL/mL (trial 3)

- 0, 5, 10, 20, 30, 40, 50 and 60 nL/mL (trial 4)

With S9:

- 0, 10, 20, 30, 40, 50, 60 and 80 nL/mL (trial 1)

- 0, 10, 20, 30, 40, 50, 60 and 80 nL/mL (trial 2)

- 0, 30, 40, 50, 60, 80 and 100 nL/mL (trial 3)

 

Positive controls (methyl methanesulphonate at 5 nL/mL without S9 and 3-methylcholanthrene at 2.5 µg/mL with S9) induced the appropriate response. In experiment without S9, mutagenic responses in trials 1, 2, 3 and 4 were inconclusive, questionable, negative and negative, respectively. In experiment with S9, mutagenic responses in trials 1, 2 and 3 were negative, negative and inconclusive, respectively. Overall, d-limonene was not considered as mutagenic in either presence or absence of S9 mix. Cytotoxicity was observed in one or more replicates tested at or above 50 nL/mL.

 

Therefore, d-limonene was not considered as mutagenic in mouse lymphoma L5178Y cells and does not need to be classified according to Directive 67/548/EEC and CLP Regulation (EC) No 1272/2008.