Ethylene di(S-thioacetate)

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.10 (Mutagenicity - In Vitro Mammalian Chromosome Aberration Test)

Deviations:

no

GLP compliance:

yes

Type of assay:

in vitro mammalian chromosome aberration test

Test material

Test material information

Constituent 1

Reference substance name:

Mercaptoacetic acid

EC Number:

200-677-4

EC Name:

Mercaptoacetic acid

Cas Number:

68-11-1

Molecular formula:

C2H4O2S

IUPAC Name:

sulfanylacetic acid

Details on test material:

Test compound: Thioglycolic acid
CAS no.: 68-11-1
Source: Elf Aquitaine production
Batch: 121092
Purity: 99.50%
Storage: room temperature and protected from light

Method

Species / strain

Species / strain / cell type:

other: Human lymphocytes

Metabolic activation:

with and without

Metabolic activation system:

10% S9 mix, prepared from a liver microsomal fraction (S9) of  rats induced with Aroclor 1254. 

Test concentrations with justification for top dose:

Without S9: 0, 30, 100 and 300 µg/ml
With S9: 0, 100, 300 and 1000 µg/ml

Vehicle / solvent:

distilled water

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:

For each culture, heparinised whole blood were added to culture medium  containing a mitogen (phytohaemogglutinin) and incubated at 37°C. After  48 hours, the conditions of treatment were as follows, using 2  cultures/experimental point:  . without S9 mix, the test or control substances remained in the culture  medium either for 24 hours or for 48 hours, until harvest, . with S9 mix, the test or control substances remained in the culture  medium for 2 hours. The cells were then rinsed and fresh culture medium  was added. The cultures were then incubated until the appropriate harvest  time, 24 and 48 hours. Each culture was then treated for 2 hours with a colcemid solution to  block them at the metaphase-stage of mitosis and harvested. The  chromosomal preparations were stained and screened microscopically for  mitotic index and for aberrations: 200 well-spread metaphases per dose  were read, whenever possible.

Evaluation criteria:

A reproducible and statistically significant increase in the aberrant  cells frequency for at least one of the doses is considered as a positive  response.

Statistics:

 X² test

Results and discussion

Test results

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

Remarks on result:

other: strain/cell type: Human lymphocytes

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

Frequency of aberrant cells (%)

	-S9				+S9
Dose	24 hours		48 hours		24 hours		48 hours
(µg/ml)	+Gap -Gap		+Gap  -Gap		+Gap -Gap		+Gap   -Gap
0	0	0	1.5	0	0	0	0.5	0
30	0	0	1.0	0.5
100	0.5	0.5	0.5	0	0	0	0	0
300	2.0	0	4.5	1.5	2.0	0.5	0.5	0
1000					1.0	0.5	0	0
+ve control	23.8	21.3			13.5	13.5

Mitotic index (% of control)

Dose	-S9		+ S9
µg/ml	24 hours	48 hours	24 hours	48 hours
30	136	78	82	81
100	100	95	124	81
300	39	89	93	100
1000	0	0	91	73
3000	0	0	0	12
5000	0
+ve control	67		33

Applicant's summary and conclusion

Conclusions:

Under the test conditions applied, TGA did not show signs of induced chromosomal abberation in human lymphocytes. Therefore it can be considered as non cytogenic.

Executive summary:

The potential of 2-thioglycolic acid to induce structural chromosome aberrations in human lymphocytes was evaluated according to OECD 473 and EC 92/69/EEC B.10 guidelines in compliance with the Principles of Good Laboratory Practice. The 2-thioglycolic acid was tested with or without a metabolic activation system (rat liver S9 mix) (2 cultures/experimental point) at the dose levels of 30, 100 and 300 µg/ml without S9 mix, and 100, 300 and 1000 µg/ml with S9 mix. Without S9 mix: the cultures were incubated with the test or control substances which remained in the culture medium, until the appropriate harvest time : 24 and 48 hours, with S9 mix: the test or control substances remained in a culture medium containing 15% S9 mix (10% S9/S9 mix) for 2 hours. The cells were then centrifuged, the treatment medium removed, the cells resuspended in fresh culture medium. The cultures were then incubated until the appropriate harvest time: 24 and 48 hours. Two hours before harvesting, the cells were treated with a colcemid solution to block them at the metaphase-stage of mitosis. The chromosomal preparations were stained and screened microscopically for mitotic index and for aberrations: 200 well-spread metaphases per dose were read, whenever possible. 2-thioglycolic acid did not induce any noteworthy increase in the number of cells with structural chromosome aberration, both with and without S9 mix, in either harvest time.