2-methylbutan-1-ol

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

18 August 2008 - 16 September 2008 (experimental)

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study conducted in compliance with GLP regulations, acceptable for assessment with restrictions (no purity of test substance given)

Justification for type of information:

see category approach "Pentanoles"

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

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:

Pentanol, branched and linear

EC Number:

305-536-1

EC Name:

Pentanol, branched and linear

Cas Number:

94624-12-1

Molecular formula:

C5 H12 O

IUPAC Name:

Reaction mass of 2-methylbutan-1-ol and pentan-1-ol

Details on test material:

- Name of test material (as cited in study report): Oxooil LS5
- Physical state: amber coloured liquid
- Analytical purity: no data

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/Ca (CBA/CaO1aHsd) strain

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Radan UK Limited, Bicester, Oxon, UK
- Age at study initiation: eight to twelve weeks old
- Weight at study initiation: 15 to 23 g
- Housing: individually
- Diet (ad libitum): 2014 Teklad Global Rodent diet supplied by Harlan Teklad, Blackthorn, Bicester, Oxon, UK
- Water (ad libitum): tap water
- Acclimation period: at least five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 25
- Humidity (%): 30 to 70
- Air changes (per hr): approximately fifteen changes per hour
- Photoperiod (hrs dark / hrs light): 12 / 12

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

- undiluted or
- 50 % or 25 % v/v in acetone/olive oil 4:1

No. of animals per dose:

4 mice/group

Details on study design:

RANGE FINDING TESTS:
Using available information regarding the systemic toxicity / irritancy potential of the test material, a preliminary screening test was performed using one mouse. The mouse was treated by daily application of 25 µL of the undiluted test material to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The mouse was observed twice daily on Days 1, 2 and 3 and once daily on Days 4, 5 and 6. Any signs of toxicity or excessive local irritation noted during this period were recorded. The bodyweight was recorded on Day 1 (prior to dosing) and on Day 6.

- Irritation: The preliminary screening test suggested that the test material would not produce systemic toxicity or excessive local irritation at the highest suitable concentration (undiluted).
No signs of systemic toxicity were noted.


MAIN STUDY

TREATMENT PREPARATION AND ADMINISTRATION:
Groups of four mice were treated with the undiluted test material or the test material at concentrations of 50 % or 25 % v/v in acetone/olive oil 4:1. The mice were treated by daily application of 25 µL of the appropriate concentration of the test material to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3).

A further group of four mice received the vehicle alone in the same manner.

Five days following the first topical application of the test material (Day 6) all mice were injected via the tail vein with 250 µL of phosphate buffered saline (PBS) containing 3H-methyl thymidine 3HTdR: 80 µCi/mL, specific activity 2.0 Ci/mmol, GE Healthcare UK Ltd) giving a total of 20 µCi to each mouse.

Approximately five hours following the administration of 3HTdR all mice were sacrificed by carbon dioxide asphyxiation. The draining auricular lymph nodes from the four mice were excised and pooled for each experimental group. For each group 1 mL of PBS was added to the pooled lymph nodes. A single cell suspension of pooled lymph node cells was prepared and further treated.

Finally, 3HTdR incorporation was measured by ß-scintillation counting.

- Criteria used to consider a positive response:
The proliferation response of lymph node cells was expressed as the number of radioactive disintegrations per minute per lymph node (disintegrations per minute/node) and as the ratio of 3HTdR incorporation into lymph node cells of test nodes relative to that recorded for the control nodes (Stimulation Index).
The test material is regarded as a sensitiser if at least one concentration of the test material results in a threefold or greater increase in 3HTdR incorporation compared to control values. Any test material failing to produce a threefold or greater increase in 3HTdR incorporation is classified as a "non-sensitiser".

Positive control substance(s):

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

Results and discussion

Positive control results:

One group of five animals was treated with 50 µL (25 µL per ear) of a-Hexylcinnamaldehyde, Tech, 85 % as a solution in acetone/olive oil 4:1 at a concentration of 15 % v/v. A further group of five animals was treated with acetone/olive oil 4:1 alone.
The stimulation index was determined to be 10.91. Thus, a-Hexylcinnamaldehyde was a sensitiser under the conditions of the test.

In vivo (LLNA)

Results

Parameter:

SI

Remarks on result:

other: A stimulation index of less than 3 was recorded for the undiluted test material and the test material at concentrations of 50 % and 25 % v/v in acetone/olive oil 4: 1.

Any other information on results incl. tables

There were no deaths. No signs of systemic toxicity were noted in the test or control animals during the test. Bodyweight changes of the test animals between Day 1 and Day 6 were comparable to those observed in the corresponding control group animals over the same period.

Results: Disintegrations per minute, disintegrations per minute/node and stimulation index

 

Concentration (% v/v) in acetone:olive oil 4:1	dpm	dpm / Node^a	Stimulation index^b	Result
Vehicle	7569.28	946.16	na	na
25	8788.34	1098.54	1.16	negative
50	6566.09	820.76	0.87	negative
100	7964.42	995.55	1.05	negative

 

^a = disintegrations per minute/node obtained by dividing the disintegrations per minute value by 8 (total number of lymph nodes)

^b = stimulation index of 3.0 or greater indicates a positive result

dpm = disintegrations per minute

na = not applicable

Applicant's summary and conclusion

Interpretation of results:

not sensitising