1-Octanamine, N,N-dimethyl-, N-oxide

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

between 19 December 2007 and 22 January 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: An appropriate current method was used according to the physical properties of the test material.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.42 (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:

N,N-dimethyl-N-octylhydroxylamine

EC Number:

607-854-9

Cas Number:

2605-78-9

Molecular formula:

CH3(CH2)7N(CH3)2O

IUPAC Name:

N,N-dimethyl-N-octylhydroxylamine

impurity 1

Reference substance name:

Dimethyl(octyl)amine

EC Number:

230-939-3

EC Name:

Dimethyl(octyl)amine

Cas Number:

7378-99-6

Molecular formula:

C10H23N

IUPAC Name:

N,N-dimethyloctan-1-amine

impurity 2

Reference substance name:

Methanol

EC Number:

200-659-6

EC Name:

Methanol

Cas Number:

67-56-1

Molecular formula:

CH4O

IUPAC Name:

Methanol

impurity 3

Test material form:

liquid: viscous

Specific details on test material used for the study:

- Analytical purity: 82.3%
- Purity test date: Not available
- Lot/batch No.: GN-8
- Expiration date of the lot/batch: Not available
- Appearance: Amber coloured, extremely viscous liquid
- Storage: In the dark at room temperature
- Additional information on test material used for the study: It was attempted to purify the substance to a purity of >80% by using an alternative synthetic route, as opposed to the usual commercial route of synthesis which results in a purity of the substance of approximately 40% in water. This alternative synthetic route generated the substance at 82.3% purity, however it also generated an impurity (methanol at 4.0%) which is not present in the commercial substance. Based on the classification and labelling of methanol, it is considered that this additional impurity would not have an influence on any of the endpoints discussed in this dossier other than the acute oral toxicity study. Therefore all studies (including the one covering this endpoint) contained in this dossier (other than the acute oral toxicity study) were conducted on the 82.3% pure substance containing the 4.0% methanol impurity. The acute oral toxicity study has been conducted on the commercially generated substance at a purity of approximately 40% in water.

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/Ca (CBA/CaOlaHsd)

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan UK Limited, Bicester, Oxon, UK
- Age at study initiation: 8 to 12 weeks
- Weight at study initiation: 15 to 23g
- Housing: Individually housed in suspended solid floor polypropylene caged furnished with soft wood flakes.
- Diet (e.g. ad libitum): Ad libitum, Certified Rat and Mouse Diet
- Water (e.g. ad libitum): Ad libitum, Mains tap water
- Acclimation period: 5 days minimum


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-25°C
- Humidity (%): 30-70
- Air changes (per hr): 15 changes per hour
- Photoperiod (hrs dark / hrs light): twelve hours continuous light (0:600 - 18:00), twelve hours darkness

Study design: in vivo (LLNA)

Vehicle:

other: 5% Trichloroacetic acid (TCA)

Concentration:

5, 10 and 25% v/v of test substance

No. of animals per dose:

4 (all female)

Details on study design:

RANGE FINDING TESTS:
A range finding study was conducted on two mice. The mice were treated daily for three days with an application of 25µl of the appropriate concentration (25 and 50% v/v dimethyl formamide) on the dorsal surface of each ear. The mice were observed twice daily on days 1 and 2 and once prior to dosing on day 3. The surviving mouse was observed post dose on day 3 and then once a day on days 4, 5 and 6 . Toxicity and excessive signs of irritation were noted . Body weights were recorded on Day 1 and on Day 6 of the surviving mouse prior to termination (from the concentration 50% v/v dimethyl formamide).


MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3
- Exposure period: 3 Days
- Test groups: 10, 15 and 25% v/v dimethyl formamide
- Control group: Vehicle of dimethyl formamide undergoing same treatment regime as test group.
- Site: Dorsal are of both ears with an automatic micropipette, spread over the ear with the tip of the pipette.
- Frequency of applications: Daily
- Concentrations: 10, 15 and 25% v/v dimethyl formamide


B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: Day 6
- Exposure period: 5 hours
- Test groups: 10, 15 and 25 % v/v dimethy formamide
- Control group: Control group included in challenge
- Site: Tail vein
- Concentrations: 250µl of phosphate buffered saline containing 3H-methyl thymidine (3HTdR: 80 µCi/ml, specific activity 2.0 Ci/mmol, GE Healthcare UK Ltd) a total of 20µCi per mouse.
- Evaluation (hr after challenge): 5 houes after challenge

Positive control substance(s):

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

Results and discussion

Positive control results:

The positive control α-Hexylcinnamaldehyde at a concentration of 25% v/v in dimethyl formamide was found to be a sensitiser.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

ca. 1.06

Test group / Remarks:

5% concentration

Results 2

Parameter:

SI

Value:

ca. 1.82

Test group / Remarks:

10% concentration

Results 3

Parameter:

SI

Value:

ca. 2.79

Test group / Remarks:

25% concentration

Any other information on results incl. tables

Main test results: dpm and stimulation index Concentration (%v/v) in dimethyl formamide dpm Dpm/Node^a Stimulation Index^b Result Vehicle 6815.86 851.98 na na 5 7222.92 902.87 1.06 Negative 10 12409.69 1551.21 1.82 Negative 25 19043.61 2380.45 2.79 Negative dpm = Disintegrations per minute 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 results na = not applicable Positive control results: α-Hexylcinnamaldehyde, Tech 85% Concentration (% v/v) in dimethyl formamide Stimulation Index Result 5 2.11 Negative 10 2.82 Negative 25 6.73 Positive Other results: In the preliminary test, only one mortality was observed in the highest concentration (50% v/v in dimethyl formamide), which was humanely killed before the endo of the study. However, in the main test, no signs of systemic toxicity and no mortality was observed. It was also noted that the bodyweight changes of the test animals were comparable to that of the control animals between days 1 and 6 of the test.

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information

Conclusions:

In comparison to the the known positive control and stimulation index derived from the controls, the substance was found to be non sensitising.

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 Commision Directive 2004/73/EC       

Methods:       Following a preliminary screening test, three groups each of four animals, were treated with 50 µl (25 µl to each ear of the test material as a solution in dimethyl formamide at concentrations of 5%, 10% or 25% v/v. A further group of four animals was treated with dimethyl formamide alone.

Conclusion:

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