Reaction mass of 2-methylpentane and Hexanol, branched and linear and diisopropyl ether

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was performed between 15 February 2010 and 10 March 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to a valid guideline and the study was conducted under GLP conditions.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

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:

Reaction Products of C3 alcohols and C3 alkenes obtained as by-products from the manufacture of propan-2-ol by hydration of propylene

EC Number:

701-241-0

Molecular formula:

A complex and variable combination of hydrocarbons having carbon numbers predominantly in the C3, C6 & C9 chain length and oxygenated organic molecules, predominantly diisopropyl ether and hexanol (branched and linear). See diagram

IUPAC Name:

Reaction Products of C3 alcohols and C3 alkenes obtained as by-products from the manufacture of propan-2-ol by hydration of propylene

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/Ca (CBA/CaOlaHsd)

Sex:

female

Details on test animals and environmental conditions:

Animals and Animal Husbandry
Female CBAlCa (CBAlCaOlaHsd) strain mice were supplied by Harlan Laboratories UK Ltd., Bicester, Oxon, UK. On receipt the animals were randomly allocated to cages. The animals were nulliparous and non-pregnant. After an acclimatisation period of at least five days the animals were selected at random and given a number unique within the study by indelible ink-marking on the tail and a number written on a cage card. At the start of the study the animals were in the weight range of 15 to 23 g, and were eight to twelve weeks old.

The animals were individually housed in suspended solid-floor polypropylene cages furnished with softwood woodflakes. Free access to mains tap water and food (2014 Teklad Global Rodent diet supplied by Harlan Teklad, Blackthorn, Bicester, Oxon, UK) was allowed throughout the study.

The temperature and relative humidity were controlled to remain within target ranges of 19 to 25°C and 30 to 70%, respectively. Any occasional deviations from these targets were considered not to have affected the purpose or integrity of the study. The rate of air exchange was approximately fifteen changes per hour and the lighting was controlled

Study design: in vivo (LLNA)

Vehicle:

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

Remarks:

Please see below for Vehicle Determination Record

Concentration:

Each group was exposed to concentrations of 50%, 25% or 10%v/v (in acetone/olive oil 4:1)

No. of animals per dose:

Groups of four mice were treated

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 two mice, one mouse per test material concentration. The mice were treated by daily application of 25 µl of the undiluted test material or the test material at a concentration of 50% v/v in acetone/olive oil 4:1, to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The mice were 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 of each mouse was recorded on Day 1 (prior to dosing) and on Day 6.

- Lymph node proliferation response:
Clinical observations, bodyweight and mortality data are give in the results section (table 1).

No signs of systemic toxicity were noted. Marked bodyweight loss (3g) was noted in the animal treated with the undiluted test material.

Based on this information the dose levels selected for the main test were 50%, 25% and 10% v/v in acetone/olive oil 4:1.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT

- Name of test method:
Local Lymph Node Assay in the Mouse. The assay has undergone extensive inter-laboratory validation and has been shown to reliably detect test materials that are moderate to strong sensitisers.

- 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(dpm/node) and as the ratio of 3HTdR incorporation in lymph node cells of test nodes relative to that recorded for the control nodes (stimulation Index).

The test material will be 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 will be classified as a "non-sensitier".

TREATMENT PREPARATION AND ADMINISTRATION:
For the purpose of the study, the test material was used freshly prepared in acetone/olive oil 4:1. This vehicle was chosen as it produced the most suitable formulation at the required concentration. The concentrations used are given above.

Determination, by analysis, of the concentration, homogeneity and stability of the test material preparations was not appropriate because it was not specified in the Study Plan and is not a requirement of the Test Guidelines.

Groups of four mice were treated with the test material at concentrations of 50%, 25% or 10% v/v in acetone/olive oil 4:1. The preliminary screening test suggested that the test material would not produce systemic toxicity or excessive local irritation at the highest suitable concentration. 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). The test material formulation was administered using an automatic micropipette and spread over the dorsal surface of the ear using the tip of the pipette.

3H-Methyl Thymidine Administration:
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, ARC UK Ltd) giving a total of 20 µCi to each mouse.

Positive control substance(s):

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

Statistics:

None provided.

Results and discussion

Positive control results:

Current Positive Control Study for the Local Lymph Node Assay
Introduction. 
A study was performed to assess the sensitivity of the strain of mouse used at these laboratories to a known sensitiser. The methodology for the LLNA is detailed in the OECD Guideline for the Testing of Chemicals, No. 429, and Method B.42 of CommissionRegulation (EC) No. 440/2008. The study described in this document is based on these test methods but has been refined in order to reduce the number of animals required. The reduced LLNA (rLLNA) has been endorsed by the non-Commission members of the European Centre for the Validation of Alternative Methods (ECVAM) Scientific Advisory Committee (ESAC) at its 26thmeeting held on 26 – 27 April 2007 at ECVAM,Ispra,Italy.

Test Material:                                   a-Hexylcinnamaldehyde, tech., 85%
Project number:                              0039/1120
Study dates:                                     05 November 2009to11 November 2009

Methods. 
A 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 4:1at a concentration of 15% v/v. A further control group of five animals was treated with acetone/olive oil 4:1alone.

Results. 
The Stimulation Index expressed as the mean radioactive incorporation for the treatment group divided by the mean radioactive incorporation of the vehicle control group is as follows:

Concentration % v/v in acetone/olive oil 4:1 Stimulation Index (SI) Result
15 3.12 Positive

Conclusion. a-Hexylcinnamaldehyde, tech., 85% was considered to be a sensitiser under the conditions of the test.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: A stimulation index of less than 3 was recorded for the test material at concentrations of 50%, 25% and 10% v/v in acetone/olive oil 4:1. The stimulation index (SI) results are given in Table 2.

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: The radioactive disintegrations per minute (dpm) per lymph node of 406.04, 815.95 and 1115.97 were recorded for the test material at concentrations of 50%, 25% and 10% v/v in acetone/olive oil 4:1.

Any other information on results incl. tables

Table 1              Clinical Observations, Bodyweight and Mortality Data – Preliminary Screening Test

Concentration (%v/v) in acetone/olive oil 4:1	Animal Number	Bodyweight (g)		Day
				1		2		3		4	5	6
		Day 1	Day 6	Pre-Dose	Post Dose	Pre-Dose	Post Dose	Pre-Dose	Post Dose
100	S-1	21	18	0	0	0	0	0	0	0	0	0
50	S-2	20	19	0	0	0	0	0	0	0	0	0

0 = No signs of systemic toxicity

Table 2              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	5608.10	701.01	na	na
10	8927.76	1115.97	1.59	Negative
25	6527.59	815.95	1.16	Negative
50	3248.32	406.04	0.58	Negative

dpm = Disintegrations per minut

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

na =     Not applicable

Table 3              Individual Clinical Observations and Mortality Data

Concentration (% v/v) in acetone/olive oil 4:1	Animal Number	Day 1		Day 2		Day 3		Day 4	Day 5	Day 6
		Pre-Dose	Post Dose	Pre-Dose	Post Dose	Pre-Dose	Post Dose
Vehicle	1-1	0	0	0	0	0	0	0	0	0
	1-2	0	0	0	0	0	0	0	0	0
	1-3	0	0	0	0	0	0	0	0	0
	1-4	0	0	0	0	0	0	0	0	0
10	2-1	0	0	0	0	0	0	0	0	0
	2-2	0	0	0	0	0	0	0	0	0
	2-3	0	0	0	0	0	0	0	0	0
	2-4	0	0	0	0	0	0	0	0	0
25	3-1	0	0	0	0	0	0	0	0	0
	3-2	0	0	0	0	0	0	0	0	0
	3-3	0	0	0	0	0	0	0	0	0
	3-4	0	0	0	0	0	0	0	0	0
50	4-1	0	0	0	0	0	0	0	0	0
	4-2	0	0	0	0	0	0	0	0	0
	4-3	0	0	0	0	0	0	0	0	0
	4-4	0	0	0	0	0	0	0	0	0

0=      No signs of systemic toxicity

Table 4              Individual Bodyweights and Bodyweight Changes

Concentration (% v/v) in acetone/olive oil 4:1	Animal Number	Bodyweight (g)		Bodyweight Change (g)
		Day 1	Day 6
Vehicle	1-1	20	20	0
	1-2	18	18	0
	1-3	17	17	0
	1-4	18	19	1
10	2-1	20	20	0
	2-2	23	23	0
	2-3	19	18	-1
	2-4	17	18	1
25	3-1	20	19	-1
	3-2	20	20	0
	3-3	17	18	1
	3-4	18	18	0
50	4-1	20	20	0
	4-2	20	20	0
	4-3	18	19	1
	4-4	19	18	-1

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The test material was considered to be a non-sensitiser under the conditions of the test.

Executive summary:

Introduction. 

A study was performed to assess the skin sensitisation potential of the test material in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear. The method was designed to meet the requirements of the following:

OECD Guideline for the Testing of Chemicals No. 429 "Skin Sensitisation: Local Lymph Node Assay" (adopted 24 April 2002)

 Method B42 Skin Sensitisation (Local Lymph Node Assay) of Commission Regulation (EC) No. 440/2008

Methods. 

Following a preliminary screening test in which no clinical signs of toxicity were noted at a concentration of 50% v/v, this concentration was selected as the highest dose investigated in the main test of the Local Lymph Node Assay. Three groups, each of four animals, were treated with 50 µl (25 µl per ear) of the test material as a solution in acetone / olive oil 4:1 at concentrations of 50%, 25% or 10% v/v. A further group of four animals was treated with acetone / olive oil 4:1 alone.

Results. 

The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:

Concentration (% v/v) in acetone / olive oil 4:1	Stimulation Index	Result
10	1.59	Negative
25	1.16	Negative
50	0.58	Negative

Conclusion. 

The test material was considered to be a non-sensitiser under the conditions of the test.