Nonamethylenediamine

Endpoint summary

Description of key information

No experimental data for the skin sensitization effects of NMDA are available. No human evidence on sensitizing effects from the historic handling of the substance has been described. However, for MODA, a chemically very similar isomer of NMDA,a clear skin sensitization effect has been observed in a valid study. The sensitizing effect has been read across to NMDA.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

25 August 2009

Justification for type of information:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Diamines are known to be skin senitizers for a long time now and precautionary measures are adopted in the epoxy resin industry where diamines are used as hardeners. MODA is a direct isomer of NMDA and has similar acute toxicity, corrosivity and water solubility compared to NMDA. Therefore read across is considered for the endpoint sensitization. MODA is regarded as a sensitizer from a OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay) study. Two of three concentrations, in which MODA was tested, show a positive effect. Although no sensitization data from NMDA are known, there is sufficient evidence that NMDA will also be sensitizing. A worst-case classification is thus assumed.

2. SOURCE AND TARGET CHEMICAL(S)
No experimental data for the skin sensitization effects of NMDA are available. No human evidence on sensitizing effects from the historic handling of the substance has been described. However, for MODA, a chemically very similar isomer of NMDA,a clear skin sensitization effect has been observed in a valid study. The sensitizing effect has been read across to NMDA.

3. ANALOGUE APPROACH JUSTIFICATION
Valid study of structural isomer, see RAAF document in section 13.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

The mice in the main study were not weighed on arrival in error and were weighed the day after arrival as soon as this error was discovered. This deviation was considered to have not affected the integrity or validity of the study.

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

The mice in the main study were not weighed on arrival in error and were weighed the day after arrival as soon as this error was discovered. This deviation was considered to have not affected the integrity or validity of the study.

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan UK Ltd
- Age at study initiation: Approximately eight to twelve weeks (at dosing on Day 1)
- Weight at study initiation: 16.9 - 21.1 g
- Housing: individually in polycarbonate cages with woodflake bedding
- Diet (e.g. ad libitum): free access to a standard rodent diet (Rat and Mouse No. 1 Maintenance Diet)
- Water (e.g. ad libitum): potable water, freely available, from the public supply
- Acclimation period: at least five days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 23
- Humidity (%): 40 - 70
- Air changes (per hr): not stated in report
- Photoperiod (hrs dark / hrs light): 12 hours continuous artificial light and twelve hours continuous dark in each 24 period


IN-LIFE DATES: From: 30 June 2009 To: 28 July 2009

Vehicle:

dimethylformamide

Concentration:

1, 2.5 or 5% v/v

No. of animals per dose:

4

Details on study design:

RANGE FINDING TESTS:
- Compound solubility: MODA formed a clear colourless liquid at 50% in dimethylformamide
- Irritation: No signs of irritation were seen over the dosed area during the study, however underactive behaviour and partially closed eyelids were observed approximately 3 hours post dose on Day 3 (10% v/v). No signs of ill health, toxicity or irritation were seen during the study (5% v/v).
- Lymph node proliferation response: not investigated


MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: animals were assigned without conscious bias
- Criteria used to consider a positive response: not stated in report

TREATMENT PREPARATION AND ADMINISTRATION: Groups or one female were treated with one concentration of the test substance. Each mouse
was treated by daily application of 25 µl of appropriate concentration of the test substance to the dorsal surface of each ear for three consecutive days (Days 1-3). The test substance was applied to the dorsal surface of each ear using an automatic micropipette. The test substance was spread over the entire dorsal surface of the ear using the tip of the pipette

Positive control substance(s):

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

Positive control results:

A loss in bodyweight was recorded for one female receiving the positive control during the study

Parameter:

SI

Value:

ca. 4.8

Test group / Remarks:

4

Remarks on result:

other: Interpretation of results The test substance is regarded as a sensitizer if at least one concentration of the test substance results in a three-fold greater increase in 3HTdR incorporation compared to control values.

Parameter:

SI

Value:

ca. 5.3

Test group / Remarks:

4

Parameter:

SI

Value:

ca. 0

Test group / Remarks:

4

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: Disintegrations per minute are less background count of 44.15 dpm

Preliminary investigation

Mortality and clinical signs: There were no deaths observed during this study. However the following observations were noted: Group 1 (10% v/v): No signs of irritation were seen over the dosed area during the study, however underactive behaviour and partially closed eyelids were observed approximately 3 hours post dose on Day 3. Group 2 (5% v/v): No signs of ill health, toxicity or irritation were seen during the study.

Bodyweight: Bodyweight increases were recorded for both mice over the period of the study. On the basis of the results from the preliminary investigation, 5% v/v was considered a suitable high dose level for the main phase of the study.

Main phase

Mortality and clinical signs:There were no deaths and no signs of ill health or toxicity were observed during this study. However the following observations were noted: Wet or greasy fur was noted for all control and test animals post-dose from Day 1 or 2 and white dose residue on the ears was noted for one mouse dosed at 1% v/v and all animals dosed at 5% v/v. These signs had resolved completely in all animals by termination.

Bodyweight:A loss in bodyweight was recorded for one female receiving the positive control during the study. All other animals gained weight during the study.

Estimation of the proliferative response of lymph node cells:The test/control ratios obtained for 1, 2.5 and 5% v/v MODA were 4.8, 5.3 and 0.0 respectively. As a test/control ratio of 3 or more was recorded for two of the concentrations tested, MODA was considered to have the potential to cause skin sensitization (delayed contact hypersensitivity). The low result obtained for 5% v/v MODA is unusual, however as the regulatory guidelines state that the test material must be labelled as a potential skin sensitizer if any of the tested dose levels have a positive result, this result does not affect the conclusion of this study.

Group dpm/node and test control ratios

Group	Concentration % v/v	dpm	Number of lymph nodes per group	dpm/node	Test/control ratio*	Result + = positive - = negative
3	DMF	1174.55	8.0	146.82	n/a	n/a
4	1	5659.45	8.0	707.43	4.8	+
5	2.5	6227.95	8.0	778.49	5.3	+
6	5	28.65	8.0	3.58	0.0	-
7	HCA 25% v/v	16090.45	8.0	2011.31	13.7	+

*       Test/control of 3 or greater indicates a positive result

n/a       not applicable

dpm       Disintegrations per minute (less background count of 44.15 dpm)

DMF       Dimethylformamide (vehicle control)

HCA hexyl cinnamic aldehyde (positive control)

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Conclusions:

NMDA is to be regarded as a potential skin sensitizer

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Diamines are known to be skin senitizers for a long time now and precautionary measures are adopted in the epoxy resin industry where diamines are used as hardeners. MODA is a direct isomer of NMDA and has similar acute toxicity, corrosivity and water solubility compared to NMDA. Therefore read across is considered for the endpoint sensitization. MODA is regarded as a sensitizer from a OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay) study. Two of three concentrations, in which MODA was tested, show a positive effect. Although no sensitization data from NMDA are known, there is therefore strong evidence that NMDA will also be sensitizing.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Evidence from similar aliphatic diamines strongly suggest a worst case approach to classify the substance as sensitizing to skin Cat 1 (H 317).