Ethylene di(S-thioacetate)

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

GDMA is considered non-genotoxic in vitro based on experimental results as well as read-across from NaTG.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Justification for type of information:

This scenario covers the analogue approach for which the read-across hypothesis is based on (bio) transformation to common compound(s). For the REACH information requirement under consideration, the effects obtained in a study conducted with one source substance are used to predict the effects that would be observed in a study with the target substance if it were to be conducted. The same type of effect(s) or absence of effect is predicted. The predicted strength of the effects may be similar or based on a worst-case approach
The hypothesis corresponds to Scenario 1 of the RAAF. The source substance NaTG will be used to read-across two endpoints, e.g. repeated dose toxicity and toxicity to reproduction, of the target substance GDMA. Source and target substance are expected to share common metabolites. GDMA is rapidly hydrolysed after absorption into TGA and ethylene glycol, while NaTG will dissociate into TGA and sodium ion. By now, no experimental toxicokinetic data is available for GDMA. Therefore, simulated gastric acid hydrolysis as well as in vitro metabolic studies are planned to strengthen the hypothesis.
For detailed information, please refer to section 13.2.

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across source

Key result

Species / strain:

lymphocytes: human

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

other: With S9 : 1000 µg/ml. Without S9 : 300 µg/ml

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Conclusions:

Based on the read-across hypothesis, GDMA is expected to show similar effects as TGA. Therefore, GDMA is considered not to induce chromosomal abberation.

Reference 2

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From May 23, 2022 to July 05, 2022

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test using the Hprt and xprt genes)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

in vitro mammalian cell gene mutation test using the Hprt and xprt genes

Target gene:

Hprt gene

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Remarks:

CHO-K1

Metabolic activation:

with and without

Metabolic activation system:

S9

Test concentrations with justification for top dose:

-tested up to the precipitation-free concentration (500 µg/mL) without and with metabolic activation system over a 5-hour treatment period:

+/-S9-mix: 62.5, 125, 250, 500 and 1000* µg/mL (*: precipitation was observed)

Vehicle / solvent:

-Vehicle(s)/solvent(s) used: DMSO

- Justification for choice of solvent/vehicle:

This solvent is compatible with the survival of the V79 cells and the S9 activity and was chosen based on the results of the preliminary solubility test, and its suitability was confirmed with the available laboratory’s historical database.

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

7,12-dimethylbenzanthracene

ethylmethanesulphonate

Details on test system and experimental conditions:

NUMBER OF REPLICATIONS: 2

DURATION:

- Exposure duration: 5-hour treatment

- Phenotypic expression time: 8 days

- Mutant selection time (selection medium): 8 days



SELECTION MEDIUM: (F12*-SEL) for 6-TG resistant mutants contained 3.4 µg/mL 6-thioguanine (6-TG) (EX-CELL® CD CHO Serum-Free Medium for CHO Cells-SEL)



METHODS FOR MEASUREMENT OF CYTOTOXICITY

Cytotoxicity was determined by relative survival (RS), where the cloning efficiency (CE) of cells plated immediately after treatment adjusted by any loss of cells during treatment as compared with adjusted cloning efficiency in negative controls (assigned a survival of 100%).

Evaluation criteria:

Evaluation of Results:

Providing that all acceptability criteria are fulfilled, a test item is considered to be clearly positive if, in any of the experimental conditions examined:

• at least one of the test concentrations exhibits a statistically significant increase compared with the concurrent negative control,

• any of the results are outside the distribution of the laboratory historical negative control data (based 95% control limit),

• the increase of mutant frequency is concentration-related when evaluated with an appropriate trend test.



Providing that all acceptability criteria are fulfilled, a test item is considered clearly negative if, in all experimental conditions examined:

• none of the test concentrations exhibits a statistically significant increase compared with the concurrent negative control,

• there is no concentration-related increase when evaluated with an appropriate trend test, all results are inside the distribution of the historical negative control data (based 95% control limit

Statistics:

-Linear trend analysis in mutant frequency

-Bartlett's homogeneity of variance test for variance between groups

-Duncan's Multiple Range test for intergroup-differences

-Kolmogorov-Smirnov test when significant heterogenety was found

-Kruskal-Wallis one-way analysis of variance in case of a none-normal distribution

-Mann-Whitney U-test if positive result was found

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Remarks:

concentration of 62.5, 125, 250, 500 and 1000*µg/mL (*precipitation was observed)

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS

-No biologically relevant changes in osmolality of the test system were noted at the different dose levels tested.

-The pH values showed a slight dose-dependent decrease. These changes were in the physiological range.



HISTORICAL CONTROL DATA:

- Positive historical control data:
The concurrent positive controls Ethyl methanesulfonate (1.0 µL/mL) and 7, 12-Dimethyl benz[a]anthracene (20 µg/mL) caused the expected biologically relevant increase of cells with mutation frequency as compared to solvent controls and were compatible with the historical positive control data.


- Negative (solvent/vehicle) historical control data:
The mutation frequency found in the negative controls (-S9: 5.94-6.00 and +S9: 6.00-6.93) were within the 95% control limits of historical laboratory control data (-S9: 5.77–8.15 and +S9: 5.73-8.54).

Main Mutation Assay 

Day 1 and Day 8 cloning efficiencies: 
In the absence and in the presence of metabolic activation, at concentrations of 62.5, 125, 250 and 500 µg/mL a minimal cytotoxic effect (2 and 9%) were observed. At concentration of 1000 µg/mL precipitation was observed, confirming the response seen in the preliminary cytotoxicity assays. 

The Day 8 cloning efficiency data indicate that at concentrations of 62.5, 125, 250,  
500 µg/mL the cells had recovered during the expression period. The observed cloning  
efficiency was in the range of 99-101%. 

The mutation data: 

There were no biologically or statistically significant increases in mutation frequency at any concentration tested, either in the absence or in the presence of metabolic activation. There were no significant differences between treatment and control groups and no dose-response relationships were noted. All values were within the range of the laboratory historical negative control data and no dose-related increase was observed in any of the cultures. The sensitivity of the tests and the efficacy of the S9 mix were demonstrated by large and statistically significant (p < 0.01) increases in mutation frequency in the positive control cultures with Ethyl methanesulfonate (1.0 µL/mL) and 7,12-Dimethyl benz[a]anthracene (20 µg/mL). The mutation frequencies of the positive control cultures were consistent with the historical control data. 

The mutation frequency found in the negative controls (-S9:5.94-6.00 and + S9:6.00-6.93) were within the 95% control limits of historical laboratory control data (-S9:5.77 – 8.15 and + S9:5.73 - 8.54). No biologically relevant changes in osmolality of the test system were noted at the different dose levels tested. The pH values showed a slight dose-dependent decrease. These changes were in the physiological range. 

TABLE 2: CHO/HPRT MUTAGENESIS ASSAY RESULTS MAIN MUTATION ASSAY/a, and b (5-HOUR TREATMENT WITHOUT S9-MIX) Replicate 1 

TEST CONDITION	SURVIVAL TO TREATMENT				Relative- Population Growth (%) of Control	MUTANT COLONIES DISH NUMBER					TOTAL MUTANT COLONIES	CE	Absolute CE %	MUTANT FREQ. X 10-6
	Mean Colony Number	CE	Adjusted CE	RS %		1	2	3	4	5
Solvent control a	203.7	1.02	0.98	100	100	1	1	1	1	2	6	1.00	100	6.00
Pos. control (EMS 1.0 µL/mL) a	49.0	0.25	0.22	23	62	190	205	187	193	201	976	0.63	63	1549.21**
TEST ITEM
62.5 µg/mL a	202.7	1.01	0.93	95	100	2	2	2	0	0	6	1.00	100	6.00
125 µg/mL a	201.7	1.01	0.89	91	101	1	1	0	3	0	5	1.01	101	4.95
250 µg/mL a	201.3	1.01	0.91	93	99	1	1	0	1	3	6	1.00	100	6.00
500 µg/mL a	203.3	1.02	0.90	92	100	1	0	0	1	4	6	1.01	101	5.94
1000 µg/mL a*	190.7	0.95	0.84	86	98	1	0	2	0	3	6	0.98	98	6.12

Conclusions:

Under the applied test conditions, GDMA was not mutagenic to Chinese hamster ovary cells. The conclusion for gene mutation in mammalian cells is negative.

Executive summary:

In conclusion, GDMA tested up to the precipitation-free concentration (500 µg/mL) without and with metabolic activation system over a 5-hour treatment period did not induce statistically and biologically significant increases in mutant frequency compared to the solvent control. All values were within the range of the laboratory historical control data and no dose-response relationships were noted. 

Thus, it is concluded that the test item, GDMA, was not mutagenic in this In Vitro Mammalian Cell Gene Mutation Test performed with Chinese hamster ovary cells. 

Reference 3

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

05.10.2021 - 05.11.2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

Metabolic activation:

with and without

Metabolic activation system:

S9-mix

Test concentrations with justification for top dose:

Incorporation method:
- 1. experiment: 5, 1.5, 0.5, 0.15 and 0.05 µL/plate
- 2. experiment: 5, 3.3, 2.2, 1.5, 1.0, 0.7 µL/plate

Pre-incubation method
5, 1.67, 0.56, 0.19, 0.06, 0.021 µL/plate

5µL was chosen as the maximum recommended concentration according to the guideline

Vehicle / solvent:

DMSO

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

sodium azide

benzo(a)pyrene

mitomycin C

other: 2-amino anthracene and 4-Nitro-1,2-phenylene diamine

Details on test system and experimental conditions:

NUMBER OF REPLICATIONS:
- Number of cultures per concentration (single, duplicate, triplicate): triplicate
- Number of independent experiments: 3

METHOD OF TREATMENT/ EXPOSURE:
- Cell density at seeding (if applicable): 10^9 cells/mL
- Test substance added in agar (plate incorporation); preincubation; in suspension;

TREATMENT AND HARVEST SCHEDULE:
- Preincubation period, if applicable: 20min for pre-incubation method
- Exposure duration/duration of treatment: 48h


METHODS FOR MEASUREMENT OF CYTOTOXICITY
- Method, e.g.: background growth inhibition;

METHODS FOR MEASUREMENTS OF GENOTOXICIY
- number of revertant colonies

Rationale for test conditions:

- precipitation: No precipitation was found up to the highest test substance concentration

- Cytotoxicity: ≥1 µl/plate (plate incorporation method) and ≥ 1.67 µl/plate (pre-incubation method)

- concentration selection for the 2. plate incorporation method: concentrations of 3.3, 2.2, 1.5µl/plate were chosen to exclude possible mutagenicity in the upper concentration range

Evaluation criteria:

Five different analysable concentrations were used for the evaluation of the mutagenic potential of the test item.

A result is considered as clearly positive if all following criteria are fulfilled:

• A concentration-related increase, in revertants
• a clear biologically relevant increase in at least one concentration compared to the concurrent solvent control
• at least one concentration with an increase above the distribution of historical solvent control data (mean ± 3 SD).

A biologically relevant increase is described as follows:
• if in the bacteria strains TA98, TA100, TA102 the number of revertants is at least twice as high than the reversion rate of the negative controls (increase factor of at least 2.0)
• if in the bacteria strains TA1535 and TA1537 the number of revertants is at least three times higher than the reversion rate of the negative controls (increase factor of at least 3.0).

A test result is considered as clearly negative, if it does not meet the criteria above.

Statistics:

The mean values and standard deviations of each threefold determination were calculated as well as the increase factor of revertant induction (mean revertants divided by mean spontaneous revertants) of the test item solutions and the positive controls. Additionally, the absolute number of revertants (mean revertants minus mean spontaneous revertants) is given.

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Results

Plate incorporation method - 1. experiment

Strain		TA98		TA100		TA102		TA1535		TA1537
Induction		-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9
Demin. water	Mean	15	17	64	63	168	149	7	7	5	5
	sd	2.3	1.0	4.4	1.5	6.9	12.2	0.0	1.2	1.2	1.0
DMSO	Mean	14	16	60	59	167	167	7	7	4	4
	sd	1.5	1.0	1.0	3.2	10.1	10.1	0.6	1.2	1.2	1.0
Positive Controls*	Mean	515	148	595	1480	653	885	408	119	113	124
	sd	39.5	27.7	25.7	21.2	48.2	44.1	13.9	4.6	4.6	8.0
	f(I)	36.79	9.25	9.30	25.08	3.89	5.30	58.29	17.00	28.25	31.00
5 µL/plate	Mean	0	4	0	0	0	26	0	1	0	0
	sd	0.0	1.5	0.0	0.0	0.0	5.0	0.0	0.6	0.0	0.6
	f(I)	0.00	0.25	0.00	0.00	0.00	0.16	0.00	0.14	0.00	0.00
1.5 µL/plate	Mean	10	13	0	30	41	169	2	6	0	4
	sd	2.0	1.5	0.0	1.2	5.0	10.1	1.0	1.0	0.0	1.0
	f(I)	0.71	0.81	0.00	0.51	0.25	1.01	0.29	0.86	0.00	1.00
0.5 µL/plate	Mean	15	19	46	45	167	163	5	6	5	4
	sd	4.0	3.1	1.2	4.6	16.7	8.3	0.6	0.6	0.6	0.6
	f(I)	1.07	1.19	0.77	0.76	1.00	0.98	0.71	0.86	1.25	1.00
0.15 µL/plate	Mean	17	24	60	46	172	159	6	5	4	5
	sd	1.5	1.5	2.0	5.5	4.0	6.1	1.0	0.6	0.0	0.6
	f(I)	1.21	1.50	1.00	0.78	1.03	0.95	0.86	0.71	1.00	1.25
0.05 µL/plate	Mean	16	21	61	52	156	159	6	6	4	4
	sd	3.2	1.5	2.1	4.6	8.0	10.1	1.0	0.6	1.0	0.6
	f(I)	1.14	1.31	1.02	0.88	0.93	0.95	0.86	0.86	1.00	1.00

f(I) = increase factor

bold marked values = relevant increase in the number of revertants

italic marked values = cytotoxicity

 

Plate incorporation method - 2. experiment

Strain		TA98		TA100		TA102		TA1535		TA1537
Induction		-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9
Demin. water	Mean	11	16	60	62	161	140	7	7	4	5
	sd	1.2	1.0	4.5	5.5	8.3	6.9	1.5	2.1	1.2	1.5
DMSO	Mean	11	16	50	49	160	165	8	8	4	3
	sd	2.0	3.0	4.9	3.2	10.6	10.1	1.0	1.2	0.6	0.6
Positive Controls*	Mean	368	71	275	1384	392	424	188	136	135	120
	sd	44.5	8.3	39.5	112.9	22.3	25.0	16.0	10.6	6.1	10.6
	f(I)	33.45	4.44	4.58	28.24	2.43	2.57	26.86	17.00	33.75	40.00
5 µL/plate	Mean	0	0	0	0	0	40	0	0	0	0
	sd	0.0	0.0	0.0	0.0	0.0	9.5	0.0	0.0	0.0	0.0
	f(I)	0.00	0.00	0.00	0.00	0.00	0.24	0.00	0.00	0.00	0.00
3.3 µL/plate	Mean	0	3	0	0	0	153	0	4	0	1
	sd	0.0	1.0	0.0	0.0	0.0	9.2	0.0	1.2	0.0	0.6
	f(I)	0.00	0.19	0.00	0.00	0.00	0.93	0.00	0.50	0.00	0.33
2.2 µL/plate	Mean	0	11	0	44	0	152	0	3	0	3
	sd	0.0	2.0	0.0	2.5	0.0	8.0	0.6	0.6	0.0	0.6
	f(I)	0.00	0.69	0.00	0.90	0.00	0.92	0.00	0.38	0.00	1.00
1.5 µL/plate	Mean	1	10	0	42	168	151	2	3	0	5
	sd	1.7	1.5	0.0	1.2	16.0	8.3	0.0	1.5	0.0	1.5
	f(I)	0.09	0.63	0.00	0.86	1.05	0.92	0.25	0.38	0.00	1.67
1.0 µL/plate	Mean	4	9	44	45	173	173	2	9	2	3
	sd	1.0	0.6	2.0	3.8	4.6	6.1	0.6	1.2	1.2	0.6
	f(I)	0.36	0.56	0.88	0.92	1.08	1.05	0.25	1.13	0.50	1.00
0.7 µL/plate	Mean	6	12	45	50	161	155	8	6	4	4
	sd	1.2	1.0	1.7	5.8	8.3	16.2	1.5	1.5	1.2	0.0
	f(I)	0.55	0.75	0.90	1.02	1.01	0.94	1.00	0.75	1.00	1.33

f(I) = increase factor

bold marked values = relevant increase in the number of revertants

italic marked values = cytotoxicity

 

Pre- incubation method

Strain		TA98		TA100		TA102		TA1535		TA1537
Induction		-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9
Demin. water	Mean	11	14	53	52	153	147	8	7	4	5
	sd	2.1	2.1	4.0	4.0	4.6	4.6	1.5	2.1	1.5	1.0
DMSO	Mean	12	16	51	53	147	153	8	7	3	4
	sd	0.6	2.3	2.1	1.0	6.1	6.1	2.1	1.7	0.6	0.6
Positive Controls*	Mean	416	116	225	1280	739	619	269	88	62	141
	sd	28.8	18.3	26.0	76.3	37.8	28.1	24.4	6.9	6.0	18.0
	f(I)	34.67	7.25	4.25	24.15	4.83	4.05	33.63	12.57	20.67	35.25
5 µL/plate	Mean	0	6	0	0	0	44	0	0	0	0
	sd	0.0	1.2	0.0	0.0	0.0	6.0	0.0	0.0	0.0	0.0
	f(I)	0.00	0.38	0.00	0.00	0.00	0.29	0.00	0.00	0.00	0.00
1.67 µL/plate	Mean	1	11	0	19	86	160	3	5	0	4
	sd	1.2	1.5	0.0	6.2	4.0	6.9	1.2	2.1	0.0	0.6
	f(I)	0.08	0.69	0.00	0.36	0.59	1.05	0.38	0.71	0.00	1.00
0.56 µL/plate	Mean	9	12	43	50	163	156	6	6	3	4
	sd	0.6	2.1	1.7	2.5	12.2	4.0	2.3	1.2	1.5	0.6
	f(I)	0.75	0.75	0.84	0.94	1.11	1.02	0.75	0.86	1.00	1.00
0.19 µL/plate	Mean	12	15	52	50	144	152	5	6	3	5
	sd	1.5	0.6	3.2	3.5	4.0	4.0	0.6	0.6	0.6	1.5
	f(I)	1.00	0.94	1.02	0.94	0.98	0.99	0.63	0.86	1.00	1.25
0.06 µL/plate	Mean	11	15	50	51	152	155	6	8	4	4
	sd	1.0	1.0	1.0	3.0	10.6	6.1	1.2	2.5	0.6	0.6
	f(I)	0.92	0.94	0.98	0.96	1.03	1.01	0.75	1.14	1.33	1.00
0.021 µL/plate	Mean	11	16	52	47	149	147	7	6	3	5
	sd	1.5	2.5	2.5	3.0	2.3	8.3	1.5	0.6	0.6	1.5
	f(I)	0.92	1.00	1.02	0.89	1.01	0.96	0.88	0.86	1.00	1.25

f(I) = increase factor

bold marked values = relevant increase in the number of revertants

italic marked values = cytotoxicity

Conclusions:

Based on the results of this study it is concluded that Thiocure® 120 is not mutagenic in the Salmonella typhimurium strains TA98, TA100, TA102, TA1535 and TA1537 in the presence and absence of metabolic activation under the experimental conditions in this study.

Executive summary:

This study was performed in order to evaluate the mutagenic potential of Thiocure^® 120 in the Bacterial Reverse Mutation Test using five strains of Salmonella typhimurium (TA98, TA100, TA102, TA1535 and TA1537) based on the most recent Guidelines OECD 471 (2020) and EU Method B.13/14 (2008). The test substance was tested with concentrations of 5, 1.5, 0.5, 0.15, 0.05 µL/plate and 5, 3.3, 2.2, 1.5, 1.0, 0.7 µL/plate in two independent experiments using plate incorporation method as well as 5, 1.67, 0.56, 0.19, 0.06, 0.021 µL/plate in one experiment using the pre-incubation method. No precipitation was observed, however, the substance showed cytotoxicity at concentrations ≥ 1µl/plate. After 48h of exposure no significant increase in the number of revertant colonies could be observed. Therefore it is concluded, that Thiocure^® 120 is not mutagenic in bacteria.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

GDMA is considered non-genotoxic in vivo based on read-across from structurally related compounds.

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Gene mutation in bacteria:

Studies according to OECD 471 are available for target and source substance. Both substances show no potency to induce gene mutation in bacteria.

Chromosomal aberration:

An in vitro study according to EOCD 473 is available for TGA, the common metabolite of GDMA and TGA. No structural chromosome aberrations were observed in the tested cells, therefore it is concluded that TGA does not induce chromosomal aberration. Based on the read-across hypothesis, GDMA is rapidly hydrolysed to TGA and ethylene glycol. Therefore, GDMA is expected to show similar effects as TGA and can be considered as negative in chromosomal aberration assay.

Gene mutation in mammalian cells:

An in vitro study according to OECD 476 is available for GDMA and for ATG, a surrogate of NaTG, but not for NaTG itself. No potential for gene mutation in mammalian cells was observed for both substances. Same metabolism is predicted for ATG as for NaTG, however, it is not determined in this justification whether data on ATG can be used to predict toxic properties of GDMA. Therefore these data cannot be used to support the read-across hypothesis.

To support the read-across hypothesis, in vitro toxicokinetic studies (simulated gastric acid hydrolysis and in vitro metabolism using human liver microsomes) will be conducted.