3,5-diiodothyronine

Endpoint summary

Description of key information

Due to the physical chemical properties in vitro studies were not applicable for this substance.

An in vivo study on the skin sensitisating potential was performed (LLNA-test according to OECD 429).

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.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vitro

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

an in vitro skin sensitisation study does not need to be conducted because the available in vitro test methods are not applicable for the substance and therefore an in vivo skin sensitisation study was conducted

Justification for type of information:

Due to the low solubility of the substance in vitro test methods could not be applied for the test item. Thus an in vivo study (LLNA test) was conducted.

Reference 2

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

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)

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.

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)

Key result

Parameter:

SI

Value:

0.74

Test group / Remarks:

10% group

Key result

Parameter:

SI

Value:

0.85

Test group / Remarks:

25% group

Key result

Parameter:

SI

Value:

0.93

Test group / Remarks:

50% group

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.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available