Poly(oxy-1,2-ethanediyl), .alpha.,.alpha.'-2-butyne-1,4-diylbis[.omega.-hydroxy-

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:

2012

Report date:

2012

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(2010)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

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:

Hydroxyethylated 2-butyne-1,4-diol

EC Number:

608-711-3

Cas Number:

32167-31-0

Molecular formula:

C4 H6 O2 (C2 H4 O) n, where 1 < n < 4.5

IUPAC Name:

Hydroxyethylated 2-butyne-1,4-diol

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): Golpanol BEO
- Physical state: clear yellow, liquid
- Analytical purity: 99.4%
- Lot/batch No.: 92713124U0
- Expiration date of the lot/batch: July 11, 2013
- Storage condition of test material: Room temperature
- Homogeneity: The test substance appeared to be homogeneous.

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/CaCrl

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Animal strain: mouse; CBA/CaCrl (Pre-test: CBA/CaOlaHsd)
- Source: Charles River, UK (Pre-test: Harlan Winkelmann GmbH, Germany)
- Age at study initiation: 8 - 11 weeks
- Mean weight at study initiation: ca. 16.2 - 20.5 g
- Housing: 5/cage; Makrolon cages, type II/III
- Diet: Pelleted standard diet, Harlan Laboratories B.V., Horst, Netherlands; ad libitum
- Water: Tap water ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2
- Humidity (%): 35- 65
- Air changes (per hr): approx. 10
- Photoperiod (hrs dark / hrs light): 12 / 12

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

50%, 25% and 10%

No. of animals per dose:

5

Details on study design:

RANGE FINDING TESTS:
- Compound solubility: The highest test item concentration, which could be technically used, was 100%. The dilutions were formulated in acetone/olive oil/4:1 (v/v) (AOO).
To determine the highest non-irritant test concentration that does not induce signs of systemic toxicity at the same time, a pre-test was performed in two animals. Two mice were treated by topical application to the dorsal surface of each ear with test item concentrations of 50% (w/w) and 100% once daily each on three consecutive days. Prior to the first application of the test item and before sacrifice the body weight was determined. Clinical signs were recorded at least once daily. Eventual signs of local irritation were documented and a score was used to grade a possible reddening of the ear skin. Furthermore, prior to the first application of the test item (day 1), on day 3 and before sacrifice (day 6) the ear thickness was determined using a micrometer. Additionally, for both animals, the ears were punched after sacrifice (day 6) at the apical area using a biopsy punch (Ø 8 mm) and were immediately pooled per animal and weighed using an analytical balance. Eventual ear irritation was considered to be excessive if reddening of the ear skin of a score value V3 was observed at any observation time and/or if an increase in ear thickness of V25% was recorded on day 3 or day 6. The measured ear weight was also considered in this evaluation.
At the tested concentrations the animals did not show any signs of systemic toxicity. On day 4 and day 5, the animal treated with the undiluted test item showed an erythema of the ear skin (Score 1). Other signs of irritation or signs of systemic toxicity were not observed.
Additionally, at both tested concentrations, an increase in ear weight was observed that exceeded the threshold value of 25% for excessive local skin irritation mentioned in OECD guideline 429. Measurement of ear thickness did not confirm the ear weight, but was increased at 100% (+ 18.9%). Thus, the test item in the main study was assayed at 10, 25, and 50% (w/w).

MAIN STUDY
TREATMENT SCHEME
Vehicle control group 1: AOO
Test group 2: 10% test item in AOO
Test group 3: 25% test item in AOO
Test group 4: 50% test item in AOO

EXPERIMENTAL PROCEDURE
- Route of application: Epicutaneously to the dorsum of both ears
- Application volume: 25 μL per ear
- Site of application: Dorsal surface of both ears
- Frequency of application: 3 consecutive applications (day 0 – day 2) to the same application site
- Administration of 3H-Methyl Thymidine: Five days after the first topical application 250 µL of phosphate-buffered saline (PBS) containing 20.2 µCi of 3HTdR (equivalent to approximately 80.9 µCi/mL 3HTdR) were injected into each test and control mouse via the tail vein.
- Determination of Incorporated 3HTdR: Approximately five hours after treatment with 3HTdR all mice were sacrificed. The draining lymph nodes were rapidly excised and pooled for each animal (2 nodes per animal). Single cell suspensions of pooled lymph node cells were prepared. The level of 3HTdR incorporation was measured on a beta-scintillation counter (Tricarb 2900 TR, Perkin Elmer (LAS) GmbH, 63110 Rodgau, Germany). 3HTdR incorporation was expressed as the number of radioactive disintegrations per minute (DPM).
- Determination of Lymph Node Weight and Cell Count: After excision, the lymph nodes were pooled per animal and weighed immediately using an analytical balance. Furthermore, the lymph node cell count was determined for each animal using a cell counter.
- Determination of ear weight: After the lymph nodes were excised, both ears of mice were punched at the apical area using a biopsy punch. For each animal both punches were immediately weighed (pooled per animal) using an analytical balance.
- Evaluation of results: The proliferative response of the lymph node cells is expressed as the number of radioactive disintegrations per minute per lymph nodes of each animal (DPM/animal) and as the ratio of 3HTdR incorporated into lymph node cells of lymph nodes of test animals relative to that recorded for lymph nodes of control animals (Stimulation Index; S.I.).

CLINICAL EXAMINATIONS
- Body weight determination: In the pre-test: prior to the first application and prior to sacrifice. In the main experiment: after the first application and prior to treatment with 3HTdR.
- Signs and symptoms: Obvious signs of systemic toxicity and/or local inflammation at the application sites were checked individually.
- Mortality: A check for moribund and dead animals was made at least once each workday.

CALCULATION OF RESULTS
- Results for each treatment group are expressed as the mean SI. The SI is derived by dividing the mean 3HTdR labelling index/mouse within each test substance group by the mean 3HTdR labelling index for the negative control (NC) group. The average SI for the NCs is then one.
- A result is regarded as positive when SI ≥ 1.55.

Positive control substance(s):

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

Statistics:

Calculation of mean and standard deviation was performed.

Results and discussion

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

3.58

Variability:

SD: 1447.5

Test group / Remarks:

10 %

Results 2

Parameter:

SI

Value:

9.94

Variability:

SD: 2158.1

Test group / Remarks:

25 %

Results 3

Parameter:

SI

Value:

9.83

Variability:

SD: 1874.3

Test group / Remarks:

50 %

Any other information on results incl. tables

Table 1 Lymph Node Cell Count

Test item concentration % (w/w)	Group Calculation
	Mean lymph node cell count (x10E06 per group)	Standard deviation	Index
Vehicle (AOO)	9.78	1.93	1.0
10 % test substance	19.28*	5.81	1.97
25 % test substance	31.83*	4.92	3.25
50 % test substance	33.42*	5.69	3.42

Index = values of the test item groups related to the mean value of the control group

* statistically significant increase in comparison to vehicle control group (p ≤ 0.05)

 

Table 2 Lymph Node Weight

Test item concentration % (w/w)	Group Calculation
	Mean Lymph Node Weight (mg per group)	Standard deviation	Index
Vehicle (AOO)	6.15	0.79	1.0
10 % test substance	9.29*	1.17	1.51
25 % test substance	13.11*	1.58	2.13
50 % test substance	13.90*	2.01	2.26

Index = values of the test item groups related to the mean value of the control group

* statistically significant increase in comparison to vehicle control group (p ≤ 0.05)

 

Table 3 Ear Weights

Test item concentration % (w/w)	Group Calculation
	Mean ear weight (mg per group)	Standard deviation	Index
Vehicle (AOO)	24.89	3.40	1.0
10 % test substance	27.46	2.38	1.10
25 % test substance	34.29*	4.08	1.38
50 % test substance	47.76*	9.71	1.92

Index = values of the test item groups related to the mean value of the control group

* statistically significant increase in comparison to vehicle control group (p ≤ 0.05)

 

Further observations:

No deaths occurred during the study period. No systemic findings were observed during the study period. On day 4 and day 5, the animals treated with 25 and 50% of the test item showed an erythema of the ear skin (score 1). The animals treated with 50% test item additionally showed an erythema of the ear skin (score 1) on day 6. Animals treated with 10% test item did not show any sign of local skin irritation.

The body weight of the animals was within the range commonly recorded for animals of this strain and age.  

Applicant's summary and conclusion

Interpretation of results:

Category 1B (indication of skin sensitising potential) based on GHS criteria

Conclusions:

Based on the results, the EC 3 will be in the range of > 2 % and < 10 % which warrents classification as skin sensitizer Cat. 1B.