Hexadecyl 3,5-bis-tert-butyl-4-hydroxybenzoate

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

The test results indicated that the test substance was non-mutagenic.

Link to relevant study records

Reference

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24-Jul-2012 to 25-Sep-2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study has been performed according to OECD and/or EC guidelines and according to GLP principles.

Qualifier:

according to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)

Deviations:

no

Principles of method if other than guideline:

The recommendations of the “International Workshop on Genotoxicity Tests Workgroup” (the IWGT), published in the literature (Clive et al., 1995, Moore et al., 1999, 2000, 2002, 2003, 2006 and 2007).

GLP compliance:

yes (incl. QA statement)

Type of assay:

mammalian cell gene mutation assay

Target gene:

Thymidine kinase (TK) locus in L5178Y mouse lymphoma cells

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

- Type and identity of media:
- RPMI 1640 Hepes buffered medium (Dutch modification) containing penicillin/streptomycin (50 U/ml and 50 μg/ml, respectively), 1 mM sodium pyruvate and 2 mM L-glutamin supplemented with 10% (v/v) heat-inactivated horse serum (=R10 medium).
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: no
- Periodically "cleansed" against high spontaneous background: yes

Metabolic activation:

with and without

Metabolic activation system:

Rat liver S9-mix induced by a combination of phenobarbital and ß-naphthoflavone

Test concentrations with justification for top dose:

Dose range finding test:
Without and with S9-mix, 3 hours treatment: 1, 3.3, 10, 33 and 50 µg/mL
Without S9-mix, 24 hours treatment: 1, 3.3, 10, 33 and 50 µg/ml
Experiment 1:
Without and with S9-mix, 3 hours treatment: 0.03, 0.1, 0.3, 1, 3, 10, 33 and 100 µg/mL

Experiment 2
Without S9-mix, 24 hours treatment: 0.03, 0.1, 0.3, 1, 3, 10, 33 and 100 µg/mL
With S9-mix, 3 hours treatment: 0.03, 0.1, 0.3, 1, 3, 10, 33 and 100 μg/mL

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: ethanol
- Justification for choice of solvent/vehicle:


Test compound was soluble in ethanol and ethanol has been accepted and approved by authorities and international guidelines

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

without S9 Migrated to IUCLID6: 15 µg/mL for the 3 hours treatment period and 5 µg/mL for the 24 hours treatment period

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

other: cyclophosphamide 10 µg/mL

Remarks:

with S9

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION
- Exposure duration:
Short-term treatment
With and without S9-mix: 3 hours
Prolonged treatment period
Without S9-mix: 24 hours
- Expression time (cells in growth medium): 2 days
- Selection time (if incubation with a selection agent): 11 to 12 days

SELECTION AGENT (mutation assays): 5 µg/mL trifluorothymidine (TFT)

NUMBER OF REPLICATIONS:
- Solvent controls: Duplicate cultures
- Treatment groups and positive control: Single cultures

NUMBER OF CELLS EVALUATED: 9.6 x 10E5 cells plated/concentration

DETERMINATION OF CYTOTOXICITY
- Method: relative suspension growth (dose range finding test) and relative total growth (mutation experiments)

Evaluation criteria:

ACCEPTABILITY OF THE ASSAY
A mutation assay was considered acceptable if it met the following criteria:
a) The absolute cloning efficiency of the solvent controls (CEday2) is between 65 and 120%. An acceptable number of surviving cells (10^6) could be analysed for expression of the TK mutation.
b) The spontaneous mutation frequency in the solvent control is ≥ 50 per 10^6 survivors and ≤ 170 per 10^6 survivors.
c) The growth rate (GR) over the 2-day expression period for the negative controls should be between 8 and 32 (3 hours treatment) and between 32-180 (24 hours treatment).
d) The mutation frequency of MMS should not be below 500 per 10^6 survivors, and for CP not below 700 per 10^6 survivors.

DATA EVALUATION
Any increase of the mutation frequency should be evaluated for its biological relevance including a comparison of the results with the historical control data range.

A test substance is considered positive (mutagenic) in the mutation assay if it induces a MF of more than MF(controls) + 126 in a dose-dependent manner. An observed increase should be biologically relevant and will be compared with the historical control data range.

A test substance is considered equivocal (questionable) in the mutation assay if no clear conclusion for positive or negative result can be made after an additional confirmation study.

A test substance is considered negative (not mutagenic) in the mutation assay if:
a) None of the tested concentrations reaches a mutation frequency of MF(controls) + 126.
b) The results are confirmed in an independently repeated test.

Statistics:

The global evaluation factor (GEF) has been defined by the IWTGP as the mean of the negative/solvent MF distribution plus one standard deviation. For the micro well version of the assay the GEF is 126.

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS:
- Effects of pH: No
- Effects of osmolality: No
- Precipitation: Precipitation in the exposure medium was observed at dose levels of 33 µg/mL and above

RANGE-FINDING/SCREENING STUDIES:
- No toxicity was observed up to the precipitating dose level of 50 µg/mL in the absence and presence of S9-mix.

COMPARISON WITH HISTORICAL CONTROL DATA:
The spontaneous mutation frequencies in the solvent-treated control cultures were between the minimum and maximum value of the historical control data range and within the acceptability criteria of this assay.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
No toxicity was observed up to and including the highest tested dose level in both experiments in the absence and presence of S9-mix.

Remarks on result:

other: strain/cell type: Test system L5178Y/TK+/-3.7.2C

Remarks:

Migrated from field 'Test system'.

Conclusions:

Interpretation of results (migrated information):
negative

The mouse lymphoma assay was conducted according to OECD 476 guideline and GLP principles.

It is concluded that CYASORB® UV-2908 Light Stabilizer is not mutagenic in the mouse lymphoma L5178Y test system

Executive summary:

The spontaneous mutation frequencies in the solvent-treated control cultures were between the minimum and maximum value of the historical control data range and within the acceptability criteria of this assay.

 

Mutation frequencies in cultures treated with positive control chemicals were increased 14- and

7.9-fold for MMS in the absence of S9-mix, and 11- and 15-fold for CP in the presence of S9-mix. It was therefore concluded that the test conditions, both in the absence and presence of S9-mix, were appropriate and that the metabolic activation system (S9-mix) functioned properly.

 

In the absence of S9-mix, CYASORB® UV-2908 Light Stabilizer did not induce a significant increase in the mutation frequency in the first experiment. This result was confirmed in an independent repeat experiment with modifications in the duration of treatment time.

 

In the presence of S9-mix, CYASORB® UV-2908 Light Stabilizer did not induce a significant increase in the mutation frequency in the first experiment. This result was confirmed in an independent repeat experiment with modifications in the concentration of the S9 for metabolic activation.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Additional information from genetic toxicity in vitro:

It is concluded that CYASORB® UV-2908 Light Stabilizer is not mutagenic in the mouse lymphoma L5178Y test system.

It is concluded that CYASORB® UV-2908 Light Stabilizer is not mutagenic in the Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay.

It can be stated that during the mouse micronucleus assay performed under the conditions described, no chromosome-breakage was detected, and no evidence of potential chromosomal mugenicity could be attributed to CYASORB UV-2908.