Fatty acids, C18 unsaturated, trimers, hydrogenated

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

22 Nov - 18 Dec 2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP - Guideline study. Conclusions were drawn without discussion of results in terms of no clear dose-relationship and possible and potentially confounding irritating effects.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

conclusions were drawn without discussion of results in terms of no clear dose-relationship and possible and potentially confounding irritating effects.

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

conclusions were drawn without discussion of results in terms of no clear dose-relationship and possible and potentially confounding irritating effects.

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government of the United Kingdom, UK

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Fatty acids, C18-unsaturated, trimers, hydrogenated

IUPAC Name:

Fatty acids, C18-unsaturated, trimers, hydrogenated

Details on test material:

- Name of test material (as cited in study report): Hydrogenated Trimer Fatty Acid
- Physical state: amber coloured viscous liquid
- Substance type: UVCB
- Analytical purity: 100%
- Lot/batch No.: 12-92-29
- Expiration date of the lot/batch: 08 March 2014
- Storage condition of test material: at room temperature in the dark

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/CaOlaHsd

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories UK Ltd., Oxon, UK
- Age at study initiation: 8-12 weeks
- Weight at study initiation: 15-23 g
- Housing: The animals were individually housed in suspended solid-floor polypropylene cages furnished with softwood woodflakes.
- Diet: 2014C Teklad Global Rodent diet (Harlan Laboratories UK Ltd., Oxon, UK), ad libitum
- Water: mains tap water, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-25
- Humidity (%): 30-70
- Air changes (per hr): ca. 15
- Photoperiod (hrs dark / hrs light): 12 / 12

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

Preliminary screening test: 100%
Main test: 25, 50 and 100% (v/v)

No. of animals per dose:

Preliminary screening test: 1
Main test: 4

Details on study design:

RANGE FINDING TESTS: A preliminary screening test was performed using one mouse. The mouse was treated by daily application of 25 µl of the undiluted test item 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. Local skin irritation was scored daily according to the Draize scoring system. Any clinical signs of toxicity, if present, were also recorded. The bodyweight was recorded on Day 1 (prior to dosing) and on Day 6.
The thickness of each ear was measured using an Oditest micrometer (Dyer, PA), pre-dose on Day 1, post-dose on Day 3 and on Day 6. Any changes in the ear thickness were noted. Mean ear thickness changes were calculated between time periods Days 1 and 3 and Days 1 and 6. A mean ear thickness increase of equal to or greater than 25% was considered to indicate excessive irritation and limited biological relevance to the endpoint of sensitisation.
- Compound solubility: The test item was soluble in in acetone/olive oil (4:1 v/v) at 50% and the solution considered suitable for dosing.
- Clinical signs and Irritation: No signs of systemic toxicity or irritation indicated by an equal to or greater than 25% increase in mean ear thickness were noted. Very slight erythema (Draize score 1) was noted on both ears on Days 3 and 4.
Based on the results of the preliminary screening test, the undiluted test item and the test item at concentrations of 50% and 25% v/v in acetone/olive oil 4:1 were selected for the main test.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: ³H-Methylthymidine incorporation determined by β-scintillation.
- 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).
A test item was regarded as a sensitiser if at least one concentration of the test item resulted in a threefold or greater increase in ³HTdR incorporation compared to control values. Any test item failing to produce a threefold or greater increase in ³HTdR incorporation was classified as a "non-sensitiser".
The EC3 value was also calculated. The EC3 value is the concentration of test item expected to cause a 3-fold increase in ³HTdR incorporation. The equation used for the calculation of EC3 is:
EC3= c + [[(3−d)/(b−d)] x (a−c)]
where:
a = lowest concentration giving stimulation index > 3
b = actual stimulation index caused by ‘a’
c = highest concentration failing to produce a stimulation index of 3
d = actual stimulation index caused by ‘c’

TREATMENT PREPARATION AND ADMINISTRATION:
Animals were treated with the undiluted test item, the test item at concentrations of 25% and 50% (v/v) in acetone/olive oil (4:1 v/v) or the vehicle alone by daily application of 25 µL of the appropriate solution to the dorsal surface of each ear for three consecutive days (Days 1-3). Five days following the first topical application of the test item or vehicle (Day 6), each animal was injected with 250 µL of phosphate buffered saline (PBS) containing 20 µCi ³H-TdR (concentration: 80 µCi/mL, specific activity: 2.0 Ci/mmol) via the tail vein. Five hours following administration of ³H-TdR, animals were sacrificed and the draining auricular lymph nodes were excised and pooled for each experimental group (total: 8 nodes/group). A single cell suspension of pooled lymph node cells was prepared in PBS by gentle mechanical disaggregation through 200-mesh stainless steel gauze. The lymph node cells were rinsed through the gauze with 4 mL of PBS into a petri dish and each lymph node cell suspension was transferred into a centrifuge tube. The petri dish was washed with PBS to remove all remaining lymph node cells, and pooled lymph node cells were pelleted by centrifugation. The pellet was resuspended in PBS and re-pelleted. To precipitate macromolecules incorporating radioactive material, the pellet was resuspended in 5% trichloroacetic acid (TCA). After approx. 18 h incubation at 4°C, the precipitates were recovered by centrifugation, resuspended in TCA and transferred to scintillation fluid. ³H-TdR incorporation was measured by β-scintillation counting.

Positive control substance(s):

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

Results and discussion

Positive control results:

Treatment with the current positive control substance α-Hexylcinnamaldehyde, technical product (85%) at 25% in acetone:olive oil (4:1 v/v) resulted in a stimulation index (SI) of 6.29, thus meeting the reliability criteria for the LLNA (SI > 3).

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: see Remark

Remarks:

The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group were as follows: 25%: 2.99 50%: 4.97 100%: 2.24 EC3 value: 25.1% (using SI values for 25 and 50% for calculation) EC3 value: 86.1% (using SI values for 50 and 100% for calculation)

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: see Remark

Remarks:

The lymph nodes of all animals per group (8 nodes in total) were pooled and DPM values were measured from the pooled lymph node cell suspensions. Treatment with vehicle, 25, 50 and 100% test item resulted in DPM/node values of 1732.94, 5187.56, 8607.26 and 3882.91, respectively.

Any other information on results incl. tables

- Clinical Observations, Skin Irritation and Mortality Data

Sticky coloured residual test item on the ears was noted in all test animals. Very slight erythema on both ears was noted on Days 2 to 4, in animals treated with the undiluted test item or the test item at a concentration of 50% v/v in acetone/olive oil 4:1 (Table 1). Thickening of the ears, possibly due to the residual test item, was noted in all test animals (Table 2). A greater than 25% increase in mean ear thickness was noted in animals treated with the undiluted test item or the test item at a concentration of 50% v/v in acetone/olive oil 4:1, but was considered to be due to residual test item on the ears rather than excessive irritation. No irritation indicated by an equal to or greater than 25% increase in mean ear thickness was noted in animals treated with the test item at a concentration of 25% v/v in acetone/olive oil 4:1.

There were no deaths. No signs of systemic toxicity were noted in the test or control animals during the test.

 

Table 1. Local Skin Irritation – Main Test

Concentration	Animal No.	Local skin irritation (erythema score)
		Day 1		Day 2		Day 3		Day 4		Day 5		Day 6
		left	right	left	right	left	right	left	right	left	right	left	right
Vehicle	1-1	0	0	0	0	0	0	0	0	0	0	0	0
	1-2	0	0	0	0	0	0	0	0	0	0	0	0
	1-3	0	0	0	0	0	0	0	0	0	0	0	0
	1-4	0	0	0	0	0	0	0	0	0	0	0	0
25%	2-1	0	0	0	0	0	0	0	0	0	0	0	0
	2-2	0	0	0	0	0	0	0	0	0	0	0	0
	2-3	0	0	0	0	0	0	0	0	0	0	0	0
	2-4	0	0	0	0	0	0	0	0	0	0	0	0
50%	3-1	0	0	1	1	1	1	1	1	0	0	0	0
	3-2	0	0	1	1	1	1	1	1	0	0	0	0
	3-3	0	0	1	1	1	1	1	1	0	0	0	0
	3-4	0	0	1	1	1	1	1	1	0	0	0	0
100%	4-1	0	0	1	1	1	1	1	1	0	0	0	0
	4-2	0	0	1	1	1	1	1	1	0	0	0	0
	4-3	0	0	1	1	1	1	1	1	0	0	0	0
	4-4	0	0	1	1	1	1	1	1	0	0	0	0

 

Table 2. Mean Ear Thickness Changes

Concentration	Ear thickness (mm)
	Mean Day 1 pre-dose (n =4)	Mean Day 3 post-dose (n =4)	Mean change Day 1-3 (%)	Mean Day 6 post-dose (n =4)	Mean change Day 1-6 (%)
Vehicle	0.209	0.213	2.096	0.224	7.186
25%	0.213	0.233*	9.706	0.236	11.176
50%	0.214	0.271*	26.608**	0.239	11.696
100%	0.210	0.297*	41.369**	0.258	22.619

* Possibly due to residual test item on the ears

** > 25% increase considered to be due to residual test item on ears

 

- Body weight

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 except for one animal treated with the undiluted test item which showed a greater than expected bodyweight gain (+23.5%).

 

- Estimation of the Proliferative Response of Lymph Node Cells

The radioactive disintegrations per minute per lymph node and the stimulation index are given in Table 3.

 

Table 3. Disintegrations per Minute (dpm), Disintegrations per Minute/Node and Stimulation Index

Concentration	dpm	dpm/Node*	Stimulation Index	Result
Vehicle	13863.51	1732.94	na	na
25%	41500.47	5187.56	2.99	Negative
50%	68858.08	8607.26	4.97	Positive
100%	31063.26	3882.91	2.24	Negative

* Disintegrations per minute/node obtained by dividing the disintegrations per minute value by 8 (total number of lymph nodes)

na = not applicable

- Calculation of EC3 value

EC3= c + [[(3−d)/(b−d)] x (a−c)]

a = 50

b = 4.97

c = 25 or 100

d = 2.99 or 2.24

EC3= 25 + [[(3−2.99)/(4.97−2.99)] x (50−25)] = 25.1 (using SI values for 25% and 50% for calculation)

EC3= 100 + [[(3−2.24)/(4.97−2.24)] x (50−10)] = 86.1 (using SI values for 50% and 100% for calculation)

The concentration of test item expected to cause a 3-fold increase in ³HTdR incorporation (EC3 value) was calculated to be 25.1 or 86.1%.

Applicant's summary and conclusion

Interpretation of results:

ambiguous

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

CLP: inconclusive
DSD: inconclusive