3,5-diiodothyronine

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:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

3,5-diiodothyronine

EC Number:

213-867-7

EC Name:

3,5-diiodothyronine

Cas Number:

1041-01-6

Molecular formula:

C15H13I2NO4

IUPAC Name:

2-amino-3-[4-(4-hydroxyphenoxy)-3,5-diiodophenyl]propanoic acid

Test material form:

solid

In vivo test system

Test animals

Species:

mouse

Strain:

CBA/Ca

Sex:

female

Details on test animals and environmental conditions:

he animals were housed in IVC polycarbonate cages (5 animals per cage) suspended on stainless steel racks, in a room equipped with central air-conditioning. The room temperature was within the range of 22 ± 3°C, relative humidity was within the range of 50 - 60 %. The light regimen was set to a 12-hour light / 12-hour dark cycle. The sanitation was performed according to standard operation procedures.

Study design: in vivo (LLNA)

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

10%, 25%, 50% (w/v)
The concentration of 100% could not be prepared because of mixing of 1000mg of test item with vehicle up to a volume of 1 mL was obtained a semidry substance inappropriate for application.

No. of animals per dose:

Number of animals:
5 females – negative control (vehicle)
5 females – positive control
15 females – test item
4 females - pre-screen test, plus spare animals

Details on study design:

Day 1:
Each animal was identified and the body weight was recorded. To the dorsum of each ear 25µL of the appropriate dilution of the test item, or the vehicle alone was applied.
Days 2 and 3:
The application procedure carried out on day 1 was repeated.
Days 4 and 5: No treatment.
Day 6:
The body weight of each animal was recorded. 250µL of sterile phosphate-buffered saline (PBS)
containing 2 µCi (7.4 x 104 Bq) of 125I-iododeoxyuridine and 10-5M fluorodeoxyuridine was injected
into all test and control mice via the tail vein.
Five hours later, the animals were sacrificed. The draining auricular lymph nodes from each ear were excised and pooled in PBS for each experimental group (pooled treatment group approach).

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Results and discussion

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

0.74

Test group / Remarks:

10% group

Results 2

Key result

Parameter:

SI

Value:

0.85

Test group / Remarks:

25% group

Results 3

Key result

Parameter:

SI

Value:

0.93

Test group / Remarks:

50% group

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The skin sensitization potential of L-Tyrosine, O-(4-hydroxyphenyl)-3,5-diiodo- was evaluated by LLNA method, which basic underlying principle is that sensitizers induce a primary proliferation of lymphocytes in the auricular lymph nodes draining the site of chemical application.
In the present study, the test item was applied to the dorsum of each ear of five female mice (CBA/Ca)
per group over three consecutive days, at three concentrations. All animals survived throughout the test period without showing any clinical signs of toxicity. Calculated SI values in treated groups remained under the value of 3, which is the threshold to consider the substance as a sensitizer.
Therefore, it was not possible to calculate an EC3 value.
These results demonstrate that the test item L-Tyrosine, O-(4-hydroxyphenyl)-3,5-diiodo- was not a skin sensitizer under the test conditions of this study.