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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report Date:
2017

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
GLP compliance:
yes (incl. certificate)
Type of assay:
in vitro mammalian chromosome aberration test

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid: viscous
Specific details on test material used for the study:
Identification: Hydroxypropyl, 2-, trimethylammonium formate
Physical state/Appearance: Colourless to very light blue liquid
Batch: Chernil.20160628.B
Purity: 95.25%
Expiry Date: 28 June 2017
Storage Conditions: Room temperature in the dark until 08 November
2016 and thereafter room temperature in the dark over silica gel
Intended use/Application: Not supplied
Formulated concentrations were adjusted to allow for the stated water/impurity content (4.75%) of the test item.

Method

Species / strain
Species / strain / cell type:
lymphocytes: Human peripheral blood lymphocytes
Details on mammalian cell type (if applicable):
For each experiment, sufficient whole blood was drawn from the peripheral circulation of a
non-smoking volunteer (aged 18-35) who had been previously screened for suitability. The
volunteer had not knowingly been exposed to high levels of radiation or hazardous chemicals
and had not knowingly recently suffered from a viral infection. Based on over 20 years
in-house data for cell cycle times for lymphocytes using BrdU (bromodeoxyuridine)
incorporation to assess the number of first, second and third division metaphase cells to
calculate the average generation time (AGT) for human lymphocytes it is considered to be
approximately 16 hours. Therefore using this average the in-house exposure time for the
experiments for 1.5 x AGT is 24 hours.
The details of the donors used are:
Preliminary Toxicity Test: female, aged 21 years
Main Experiment: female, aged 30 years
Additional strain / cell type characteristics:
not applicable
Metabolic activation:
with and without
Metabolic activation system:
S9
Test concentrations with justification for top dose:
0, 102, 204, 408, 816, 1020, 1224, 1632 µg/m

The dose range for the Preliminary Toxicity Test was 6.38 to 1632 µg/mL. The maximum dose was the maximum recommended dose level.
Vehicle / solvent:
Eagle's minimal essential medium with HEPES buffer (MEM)
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
cyclophosphamide
mitomycin C
Details on test system and experimental conditions:
Cells (whole blood cultures) were grown in Eagle's minimal essential medium with HEPES buffer (MEM), supplemented “in-house” with L-glutamine, penicillin/streptomycin, amphotericin B and 10 % foetal bovine serum (FBS), at approximately 37 ºC with 5 % CO2 in humidified air. The lymphocytes of fresh heparinized whole blood were stimulated to divide by the addition of phytohaemagglutinin (PHA)

The S9 Microsomal fractions were pre-prepared using standardized in-house procedures (outside the confines of this study). Lot No’s. PB/βNF S9 25/08/16 (preliminary toxicity test) and PB/βNF S9 22/09/16 (main test) were used in this study. A copy of the S9 Certificates of Efficacy are presented in Appendix 2.
The S9-mix was prepared prior to the dosing of the test cultures and contained the S9 fraction (20% (v/v)), MgCl2 (8mM), KCl (33mM), sodium orthophosphate buffer pH 7.4 (100mM), glucose-6-phosphate (5mM) and NADP (5mM). The final concentration of S9, when dosedat a 10% volume of S9-mix into culture media, was 2%
Evaluation criteria:
The following criteria were used to determine a valid assay:
• The frequency of cells with structural chromosome aberrations (excluding gaps) in the vehicle control cultures was within the laboratory historical control data range.
• All the positive control chemicals induced a positive response (p≤0.01) and demonstrated the validity of the experiment and the integrity of the S9-mix.
• The study was performed using all three exposure conditions using a topconcentration which meets the requirements of the current testing guideline.
• The required number of cells and concentrations were analyzed.

Providing that all of the acceptability criteria are fulfilled, a test item can be considered to be clearly negative if, in any of the experimental conditions examined:
1) The number of cells with structural aberrations in all evaluated dose groups should be within the range of the laboratory historical control data.
2) No toxicologically or statistically significant increase of the number of cells with structural chromosome aberrations is observed following statistical analysis.
3) There is no concentration-related increase at any dose level

A test item can be classified as genotoxic if:
1) The number of cells with structural chromosome aberrations is outside the range of the laboratory historical control data.
2) At least one concentration exhibits a statistically significant increase in the number of cells with structural chromosome aberrations compared to the concurrent negative control.
3) The observed increase in the frequency of cells with structural aberrations is considered to be dose-related
When all of the above criteria are met, the test item can be considered able to induce chromosomal aberrations in human lymphocytes.
Statistics:
The frequency of cells with aberrations excluding gaps and the frequency of polyploid cells was compared, where necessary, with the concurrent vehicle control value using Fisher's Exact test. (Richardson et al. 1989).

Results and discussion

Test results
Key result
Species / strain:
lymphocytes:
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Remarks on result:
other: Negative for genotoxicity

Applicant's summary and conclusion

Conclusions:
The test item was non-toxic to human lymphocytes and did not induce any statistically significant increases in the frequency of cells with aberrations, using a dose range that included a dose level that was the maximum recommended dose level.
The test item, Hydroxypropyl, 2-, trimethylammonium formate was considered to be non-clastogenic to human lymphocytes in vitro.