3-methylbut-2-en-1-ol

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

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

BASF SE; Experimental Toxicology and Ecology; Ludwigshafen; Germany

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

3-methylbut-2-en-1-ol

EC Number:

209-141-4

EC Name:

3-methylbut-2-en-1-ol

Cas Number:

556-82-1

Molecular formula:

C5H10O

IUPAC Name:

3-methylbut-2-en-1-ol

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/CaOlaHsd

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Envigo, The Netherlands
- Age at study initiation: 11 weeks (pretest); 10 weeks (main test)
- Weight at study initiation: 17.5 g – 21.1 g (pretest); 17.3 g – 22.4 g (main test)
- Housing: 1 animal/cage
- Diet: ad libitum; Kliba mouse/rat maintenance diet “GLP" by Provimi Kliba SA,Switzerland.
- Water: ad libitum
- Acclimation period: min. 5 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24
- Humidity (%): 45-65
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (LLNA)

Vehicle:

methyl ethyl ketone

Concentration:

5%, 50%, 100% (Pretest)
25%, 50%, 100% (Main test)

No. of animals per dose:

2 (Pretest)
5 (Main test)

Details on study design:

PRE-SCREEN TESTS:
- Assessment of compound solubility: Yes
- Assessment of clinical signs + local effects : Yes
- Body weight determination: Yes
- Ear thickness/weight measurements: Yes
- Lymph node weight measurements: Yes

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
Prior to first application, the animals were distributed to the individual groups, received their animal numbers and were allocated to the respective cages according to the randomization instructions of „Nijenhuis, A. and Wilf, H.S.: Combinatorial Algorithms, Academic Press, New York, San Francisco, London, 1978, pp. 62 – 64“.

TREATMENT PREPARATION AND ADMINISTRATION:
Body weight determination: Individual body weights on day 0 prior to the first application and on day 5 prior to the sacrifice of the animals.
Signs and symptoms: Obvious signs of systemic toxicity and/or local inflammation at the application sites were noted for each animal
Mortality: A check for moribund and dead animals was made twice each workday (beginning and end) and once on Saturdays, Sundays and on public holidays.
Form of application: Epicutaneous
Application volume: 25 µL per ear
Site of application: Dorsal part of both ears
Frequency of application: 3 consecutive applications (day 0 – day 2) to the same application site
On study day five (about 66 to 72 hours after the last application of test substance to the ears) the mice were injected into a tail vein with 20 µCi of 3H-thymidine in 250 µL of sterile saline.

- Parameters assessed:
Determination of ear weight:
Immediately after the death of each animal a circular piece of tissue (diameter 0.8 cm) was punched out of the apical part of each ear of all animals. The weight of the pooled punches was determined for each animal.

Removal and weight determination of the lymph nodes:
Immediately after removal of the ear punches the left and right auricular lymph nodes were dissected. The weight of the pooled lymph nodes from both sides was determined for each animal.

Preparation of cell suspension and determination of cell count:
After weight determination, the pooled lymph nodes of each animal were stored in phosphate buffered saline (PBS) and a single cell suspension was prepared by carefully passing the lymph nodes through an iron mesh (mesh size 200 µm) into phosphate-buffered physiological saline. The cell count was determined using a Casy®-Counter.

Measurement of 3H-thymidine incorporation of the lymph node cells:
The remaining cell suspensions were washed with PBS and precipitated with 5% trichloro-acetic acid (TCA). Each precipitate was measured in a β-scintillation counter.

- Criteria used to consider a positive response:
A test item is regarded as a sensitizer in the LLNA if exposure to at least one concentration of the test item results in an incorporation of 3H thymidine at least 3-fold or greater than that recorded in control mice, as indicated by the stimulation index (SI ≥ 3.0). However, the biological relevance of the obtained stimulation indices are considered in conjunction with the other assessed end points (i.e. cell counts, lymph node weights, ear weights). Hereby, the thresholds used for assessment of cell counts and ear weights are represented by stimulation indices (SI) of 1.5 and 1.25, respectively.

Positive control substance(s):

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

Statistics:

3H-thymidine incorporation, cell count, lymph node weight and ear weight: Wilcoxon - Test

Results and discussion

In vivo (LLNA)

Results

Key result

Parameter:

EC3

Value:

4.9

Test group / Remarks:

3H-thymidine incorporation

Cellular proliferation data / Observations:

CELLULAR PROLIFERATION DATA
SI (3H-thymidin-incorporation)
25%: 1.01
50%: 1.81*
100%: 1.30

SI (cell counts)
25%: 1.02
50%: 1.26*
100%: 1.13

SI (lymph node weight)
25%: 0.94
50%: 1.19
100%: 1.04

EAR WEIGHTS
SI:
25%: 0.97
50%: 1.03
100%: 1.06

*p<=0.05; **p<=0.01

CLINICAL OBSERVATIONS:
No signs of systemic toxicity were noticed in all animals during general observation. No local findings were observed during the observation period.

BODY WEIGHTS:
The expected mean body weight gain was generally observed during the study.

Any other information on results incl. tables

 Pretest / Irritation Screening -Results

No signs of systemic toxicity were observed. At the tested concentrations, the animals did not show relevant signs of local irritation as confirmed by the ear weight measurements (compared to current vehicle values) and ear thickness measurements. No increase in lymph node weights (compared to current vehicle values) were observed at 5% (SI 0.97) and 50% (SI 1.00). When applied undiluted, the SI for lymph node weights slightly increased (SI 1.38).

Applicant's summary and conclusion

Executive summary:

The skin sensitizing potential of Prenol was assessed using the radioactive Murine Local Lymph Node Assay. Groups of 5 female CBA/CaOlaHsd mice each were treated with the undiluted test substance, 50% and 25% w/w preparations of the test substance in Methyl Ethyl Ketone (MEK) or with the vehicle, respectively. Additionally, untreated control animals were used for comparison versus animals of the high dose group (undiluted test substance). The study used 3 test groups and 2 control groups. Each test animal was treated with 25 μL per ear of the appropriate test-substance preparation or undiluted test substance, applied to the dorsal surface of both ears for three consecutive days. The vehicle control group was treated with 25 μL per ear of the vehicle. The second control group was untreated. Three days after the last application, 20 μCi 3H-thymidine in 250 μL sterile saline were injected into the tail vein of the mice. About 5 hours after the 3H-thymidine injection, the mice were sacrificed and the auricular lymph nodes were removed. Lymph node response was evaluated measuring 3H-thymidine incorporation (indicator of cell proliferation). Cell counts and weights of each animal’s pooled lymph nodes were also determined. In addition, a 0.8 cm diameter sample was punched out of the apical part of each ear, and for each animal, the weight of the pooled punches was determined to obtain an indication of possible skin irritation.

No signs of systemic toxicity were noticed in all animals during general observation. When applied undiluted or as 50% and 25% solution in MEK, the test substance did not induce a biologically relevant (no increase to 3-fold or above of control value = stimulation index (SI) ≥ 3) increase of 3H-thymidine incorporation into the cells from the auricular lymph nodes. Concomitantly no biologically relevant (no increase to 1.5-fold or above of control value = stimulation index (SI) ≥ 1.5) increase in lymph node cell counts was observed at all tested concentrations. However, statistically significant increases in 3H-thymidine incorporation and lymph node cell counts were noted at the 50% concentration. No relevant increase in lymph node weights was observed at all concentrations. The test-substance concentrations did not cause relevant increases in ear weights demonstrating the absence of ear skin irritation under the chosen testing conditions.

Overall, it is concluded that Prenol does not exhibit a skin sensitizing potential in the Murine Local Lymph Node Assay under the test conditions chosen.