Mercaptoacetic acid

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

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:

2001

Report date:

2001

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Ammonium mercaptoacetate

EC Number:

226-540-9

EC Name:

Ammonium mercaptoacetate

Cas Number:

5421-46-5

Molecular formula:

C2H4O2S.H3N

IUPAC Name:

ammonium sulfanylacetate

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Winkelmann GmbH, D-33178 Borchen
- Age at study initiation: 8-12 weeks
- Weight at study initiation: 16-20 g
- Housing: in groups in macrolon cage
- Diet (ad libitum): Altromin 1324 maintenace diet for rats and mice
- Water (ad libitum): municipal drinking water
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 3
- Humidity (%): 55 +/- 10
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (LLNA)

Vehicle:

other: T52-003:modified acetone/aqua/olive oil

Concentration:

20 %, 8% and 0.5 %

No. of animals per dose:

5

Details on study design:

The test item was assayed at three concentrations of 20 %, 8% and 0.5 %  respectively.  The main vehicle was modified acetone/aqua/olive oil (AAOO) to achieve  maximum solubility of the test item. Each female mouse was treated by  topical application with the selected solution to entire dorsal surface  of each once daily over three consecutive days. Five days after the first topical application treatment all mice were  injected intravenous with 3H-methyl thymidine.  Approximately 5 hours after 3H-methyl thymidine injection all mice were  sacrificed and the draining auricular lymph nodes were excised, in order  to prepare single cell suspension of the lymph node cells. The 3 H-methyl thymidine-incorporation was measured in a SS counter and  expressed as the number of disintegrations per minute (DPM).  Determination of radioactivity was performed individually for each animal. The proliferation response of lymph node cells was calculated as the  ratio of 3H-methyl thymidine incorporation into lymph node cells of test  group animals relative to that recorded for control group animals. A  stimulation index, ratio of test substance/vehicle control, was  calculated for each concentration. Additionally the EC3 value was determinated.

Positive control substance(s):

other: 1% p-phenylenediamine

Statistics:

None

Results and discussion

Positive control results:

The test control ratio for the positive control (1 % p-phenylenediamine)  was 5.3.

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

EC3

Value:

0.65

Results 2

Parameter:

SI

Value:

2.7

Test group / Remarks:

0.5%

Results 3

Parameter:

SI

Value:

17

Test group / Remarks:

8%

Results 4

Parameter:

SI

Test group / Remarks:

20%

Remarks on result:

other: Evaluation was not possible as all animals died after the third application, indicating systemic effects at his concentration.

Applicant's summary and conclusion

Interpretation of results:

Category 1A (indication of significant skin sensitising potential) based on GHS criteria

Conclusions:

Ammonium thioglycolate up from a concentration of 0.65 % caused reactions identified as sensitization, as the stimulation index was equal to or greater than 3.0.

Executive summary:

The skin sensitization potential of ammonium thioglycolate (71% solution) was investigated in local lymph node assays performed according to the OECD guideline # 429. There were 5 CBA/Ca/Ola/Hsd female mice in each of the dose and control groups, respectively. The mice received 25 µl of topical solution consisting of 0, 0.5, 8.0, or 20.0% (a.i., w/v) of ammonium thioglycolate on the dorsal surface of each ear lobe once daily for three consecutive days. p-Phenylenediamine was used as positive controls and showed satisfactory sensitisation response. Five days after the first application of solution, all mice received radiolabelled thymidine (3HTdR) by i.v. injection in thet ail vein. All mice were killed five hours after the3HTdR injection. The lymph nodes of the mice were removed and studied for proliferation with3HTdR. The values were then used to calculate the stimulation index (SI) as reported in table 21. It was concluded that both ammonium thioglycolate and sodium thioglycolate were sensitising in mice.

The stimulation indexes were  2.7 and 17.0 at concentrations of 0.5 % and 8%, respectively. Evaluation for the 20 % concentration was not possible as all animals died after the third application, indicating systemic effects at his concentration. The EC3 value (derived by linear interpolation) was at 0.65 %.