Octane-1,2-diol

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

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: Well documented and reported study fully adequate for assessment. The study was conducted according to an internationally accepted technical guideline and in compliance with GLP in a recognized contract research organization.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

of 2002

Deviations:

yes

Remarks:

Contrary to OECD 429 of 2002, but in accordance with OECD 429 of 2010, scintillation vials were filled with 10 mL of scintillation fluid for ^3H-counting. This did not compromise the validity of the study.

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Mouse (healthy females, nulliparous and non-pregnant), strain: CBA/CaOlaHsd with appropriate range of bodyweight at study start.
- Source: Harlan Netherlands, B.V. Postbus 6174, NL-5960 AD Horst / The Netherlands
- Age at treatment start (1st induction): 9 to 13 weeks.
- Weight at treatment start (1st induction): Minimum 17.1 g, maximum 22.9 g.
- Housing: Individual housing in Makrolon Type II cages.
- Bedding material: Standard softwood bedding, "Lignocel" (Schill AG, CH-4132 Muttenz, Switzerland).
- Diet (ad libitum): Pelleted standard diet, Provimi Kliba 3433, batch 40/03 mouse maintenance diet
(Provimi Kliba AG, CH-4303 Kaiseraugst, Switzerland).
- Water (ad libitum): Community tap water
- Acclimation period: 7 days under the same conventional standard laboratory conditions as the LLNA was conducted.
- Animal wellfare: AAALAC-approved laboratory in accordance with the Swiss Animal Protection Law.

Bacteriological, chemical and contaminant analyses of water and contaminant analyses of the diet were performed and archived at the testing facility.


ENVIRONMENTAL CONDITIONS

Standard laboratory conditions, environmental conditions were set at:
- Air changes per hour in the animal room: 10-15
- Temperature (°C): 22 ± 2°C
- Relative Humidity (%): 30 - 70 %
- Photoperiod (artificial lighting): 12 hrs day / 12 hrs night with music, at least during 8 hours of the light period.
Room temperature and humidity were monitored continuously and values outside of these ranges occasionally occurred, usually following room cleaning. These transient deviations were not considered to compromise the integrity or validity of the study.

Vehicle:

other: propylene glycol:water, 7:3 (v/v)

Concentration:

Topical administrations on Day 1 at the following concentrations of test material in the vehicle (w/w):
- Pre-study (non-GLP): 5, 10, 25, 50

Induction administrations on Days 1, 2 and 3 at the following concentrations of test material in the vehicle (w/w):
- Main Study (test material): 0 (vehicle control), 5, 10, 25

Induction administrations on Days 1, 2 and 3 at the following concentrations of Hexyl cinnamic aldehyde (positive control) in vehicle (% w/v):
- Main Study (positive control )* 0 (vehicle control), 5, 10, 25

* The positive control was conducted as a separate, GLP compliant study to demonstrate sensitivity of the test procedures and animal strain used in the test facility for local lymph node assays. Acetone:olive oil, 4:1 (v/v) was used as a vehicle in the positive control study. The positive control study had been conducted approximately 3 months before the present study.

No. of animals per dose:

- Pre-study (non-GLP): A total of 2 female animals for all doses
- Main Study (test material): 4 female animals per dose level
- Main Study (positive control)*: 4 female animals per dose level

* The positive control was conducted as a separate, GLP compliant study to demonstrate sensitivity of the test procedures and animal strain used in the test facility for local lymph node assays. Acetone:olive oil, 4:1 (v/v) was used as a vehicle in the positive control study. The positive control study had been conducted approximately 3 months before the present study.

Details on study design:

Pre-Test:
In a pretest (not compliant with GLP) single administration of test material concentrations at 5, 10, 25 and 50% (w/w) in the vehicle [propylene glycol:water, 7:3 (v/v)] to one ear in a total of two animals did not elicit any signs of local irritation at 5, 10 or 25% (w/w). Aprroximately 24 hours after administration slight swelling was recorded at the ear dosed with 50% (w/w). Based on these observations 25% (w/w) was concluded to be the highest suitable concentration avoiding systemic toxicity and excessive local irritation.

Treatment Preparation and Administration for the Main Test and Separate Positive Control Study:
On three consecutive days, groups of 4 female mice were treated by topical application to the dorsal surface of both ears with 25 μL/ear/day at the test or positive control material concentrations listed above in the field "LLNA – Concentration". All formulations were freshly prepared on each day of administration and dosed within 4 hours of preparation. Negative control animals received the vehicle alone.

Observations, Measurements and Endpoints (Pooled treatment group approach):
All animals were checked daily for signs of local irritation at the application site and systemic toxicity, and for mortality twice daily. In addition, bodyweights were recorded on Days 1 (prior to treatment) and 6 (prior to terminal sacrifice). On Day 6, all main study animals were injected into the tail vein ^3HTDR diluted in phosphate buffered saline at a nominal dose of ca. 19.6 µCi per mouse, in order to measure lymphocyte proliferation by radioactive labelling. Approximately five hours afterwards the draining (auricular) lymph nodes were excised and pooled for each experimental group. After sample processing and precipitating macromolecules of the lymph node cells in 5% trichloracetic acid (TCA), radioactivity measurements were performed on Day 7 or 8 on a β-scintillation counter. Radioactivity was expressed as the number of radioactive disintegrations per minute (dpm). The ratio of the proliferation (reflected by the magnitude of measured dpm/node) in treated groups to that in the vehicle control group, termed the stimulation index (SI), was subsequently calculated for each group. Background ^3HTdR levels were also measured in two 1 mL aliquots of 5% TCA and accounted for in the study results.

Criteria Used to Consider a Positive Response:
The test material is regarded as a sensitizer if at least one concentration of the test material produces a stimulation index (SI) ≥ 3.
In addition, due consideration is given to dose-relationship of the attained stimulation indices, although local toxicity and/or immunosuppression may interfere with dose-relationship.

Positive control substance(s):

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

Statistics:

Statistical assessment of dose response was unnecessary, because stimulation Indices well below 3 were attained at all tested concentrations and there was no indication of a dose related increase in DPM/lymph node.

Positive control results:

Stimulation indices (SI) of 1.00 (vehicle control), 1.5, 3.2 and 6.9 were attained in a contemporaneous positive control assay with the same strain of mice (CBA/CaOlaHsd) in response to 0 (vehicle control), 5, 10 and 25% w/v hexyl cinnamic aldehyde in acetone:olive (4:1 v/v), respectively, thus demonstrating the reliability and sensitivity of this test system and assay to detect skin sensitization potential in this laboratory.

Key result

Parameter:

SI

Value:

1.4

Test group / Remarks:

5%

Key result

Parameter:

SI

Value:

1.2

Test group / Remarks:

10%

Key result

Parameter:

SI

Value:

2

Test group / Remarks:

25%

Mortality / clinical signs:

At all test concentrations, premature deaths or signs of systemic toxicity were not evident. All vehicle control animals and animals treated with 5 or 10% w/w test material dilution were free from clinical signs or local irritation during the entire study. All animals treated with 25% w/w test material dilution showed ear swelling grade 1 (of 3, slight in degree) from approximately 2 hours after the first administration (Day 1) and erythema grade 1 (of 4, very slight in degree) from Day 2 until Day 4. By Day 5, these signs of local irritation had disappeared and all animals were entirely free from clinical signs for the remainder of the study.

Body weight:

There was no indication of adverse effects on bodyweight attributable to treatment with the test material.

Interpretation of results:

other: not sensitising

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the low stimulation indices attained in the local lymph node assay and the absence of any sensitisation responses in two maximisation tests (Magnusson Kligman) and a human repeated insult patch test (HRIPT, modified Draize assay) octane-1,2 -diol is considered not to be a skin sensitiser and does not warrant any classification regarding skin sensitisation according to European classification rules [REGULATION (EC) 1272/2008].