2,2'-iminobis[4,6-diamino-1,3,5-triazine]

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

April 13 - May 02, 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study has been performed according to OECD and/or EC guidelines and according to GLP principles.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

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

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

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:

2,2'-iminobis[4,6-diamino-1,3,5-triazine]

EC Number:

222-695-1

EC Name:

2,2'-iminobis[4,6-diamino-1,3,5-triazine]

Cas Number:

3576-88-3

Molecular formula:

C6H9N11

IUPAC Name:

N~2~-(4,6-diamino-1,3,5-triazin-2-yl)-1,3,5-triazine-2,4,6-triamine

Constituent 2

Reference substance name:

Melam

IUPAC Name:

Melam

Details on test material:

- Name of test material (as cited in study report): Melam CAS 3576-88-3
- Physical state: White powder
- Storage condition of test material: At room temperature in the dark
- Stability under storage conditions: Stable
- Hygroscopic: Yes, store in well-sealed container
- pH: 9.6 at concentration of 10%
- Stability in acetone/olive oil: not indicated
- Solubility in acetone/olive oil: not indicated

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/J

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Janvier, Le Genest-Saint-Isle, France
- Age at study initiation: Young adult animals (approx. 11 weeks old)
- Weight at study initiation: Body weight variation was within +/- 20% of the sex mean.
- Housing: Animals were group housed in labeled Makrolon cages (MIII type; height 18 cm) containing sterilised sawdust as bedding material (Litalabo, S.P.P.S., Argenteuil, France). Paper (Enviro-dri, Wm. Lillico & Son (Wonham Mill Ltd), Surrey, United Kingdom) was supplied as cage-enrichment. On Day 6, the animals were group housed in Makrolon MII type cages with a sheet of paper instead of sawdust and cage enrichment.
- Diet (e.g. ad libitum): Free access to pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany).
- Water (e.g. ad libitum): Free access to tap water.
- Acclimation period: The acclimatization period was at least 5 days before the start of treatment under laboratory conditions.
- Health inspection: A health inspection was performed prior to treatment, to ensure that the animals are in a good state of health. Special attention was paid to the ears, which were intact and free from any abnormality.

Results of analysis for diet (nutrients and contaminants), sawdust, paper and water were assessed and did not reveal any findings that were considered to have affected the study integrity. All certificates and results of analysis are retained in the NOTOX archives.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.2 23.1
- Humidity (%): 37 - 67
- Air changes (per hr): approximately 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: April 13, 2011 To: May 02, 2011

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

Preliminary irritation study: a 40% and 25% concentration
Main study: 0, 10, 25 and 40%

No. of animals per dose:

5

Details on study design:

RANGE FINDING TESTS:
A pre-screen test was conducted in order to select the highest test substance concentration to be used in the main study. In principle, this highest concentration should cause no systemic toxicity, may give moderate irritation at the most (maximum grade 2 (see section 6.7) and/or an increase in ear thickness < 25%) and is the highest concentration that can technically be applied.

The test system, procedures and techniques were identical to those used in the main study except that assessment of lymph node proliferation and necropsy were not performed. Two young adult animals per concentration were selected (in the range of 8 to14 weeks old).
Each animal was treated with one concentration on three consecutive days.

Animals were group housed in labeled Makrolon cages (MII type, height 12.5 cm). Ear thickness measurements were conducted using a digital thickness gauge prior to dosing on Days 1 and 3, and on Day 6. On Days 2 and 3, the irritation was also scored prior to dosing since it was anticipated that remnants of the test substance after dosing would hamper scoring of the ears. Animals were sacrificed after the final observation.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local Lymph Node Assay
- Criteria used to consider a positive response: DPM values are presented for each animal and for each dose group. A Stimulation Index (SI) is calculated for each group. The SI is the ratio of the DPM/group compared to DPM/vehicle control group.
If the results indicate a SI = 3, the test substance may be regarded as a skin sensitizer, based on the test guideline and recommendations done by ICCVAM.
The results were evaluated according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2007) and the Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures.
Consideration was given to the EC3 value (the estimated test substance concentration that will give a SI =3).

TREATMENT PREPARATION AND ADMINISTRATION:
Test substance preparation: The test substance formulations (w/w) were prepared within 4 hours prior to each treatment. No adjustment was made for specific gravity of the vehicle. Homogeneity was obtained to visually acceptable levels.
Rationale for vehicle: The vehicle was selected based on trial formulations performed at NOTOX and on test substance data supplied by the sponsor.

Induction - Days 1, 2 and 3:
The dorsal surface of both ears was epidermally treated (25 µL/ear) with the test substance concentration, at approximately the same time per day. The concentrations were stirred with a magnetic stirrer immediately prior to dosing. The control animals were treated the same as the experimental animals, except that the vehicle was administered instead of the test substance.

Excision of the nodes - Day 6:
Each animal was injected via the tail vein with 0.25 mL of sterile phosphate buffered saline (PBS) (Merck, Darmstadt, Germany) containing 20 µCi of 3H-methyl thymidine (PerkinElmer Life and Analytical Sciences, Boston, MA, US). After approximately five hours, all animals were killed by intraperitoneal injection with Euthasol® 20% (AST Farma BV, Oudewater, The Netherlands). The draining (auricular) lymph node of each ear was excised. The relative size of the nodes (as compared to normal) was estimated by visual examination and abnormalities of the nodes and surrounding area were recorded. The nodes were pooled for each animal in approximately 3 mL PBS.

Tissue processing for radioactivity - Day 6:
A single cell suspension of lymph node cells (LNC) was prepared in PBS by gentle separation through stainless steel gauze (diameter 125 µm). LNC were washed twice with an excess of PBS by centrifugation at 200g for 10 minutes at 4ºC. To precipitate the DNA, the LNC were exposed to 5% trichloroacetic acid (TCA) (Merck, Darmstadt, Germany) stored in the refrigerator until the next day.

Radioactivity measurements - Day 7
Precipitates were recovered by centrifugation, resuspended in 1 mL TCA and transferred to 10 mL of Ultima Gold cocktail (PerkinElmer Life and Analytical Sciences, Boston, MA, US) as the scintillation fluid. Radioactive measurements were performed using a Packard scintillation counter (2800TR). Counting time was to a statistical precision of ± 0.2% or a maximum of 5 minutes whichever came first. The scintillation counter was programmed to automatically subtract background and convert Counts Per Minute (CPM) to Disintegrations Per Minute (DPM).

Observations:
Mortality/Viability: Twice daily.
Body weights: On Day 1 (pre-dose) and Day 6 (prior to necropsy).
Clinical signs: Once daily on Days 1-6 (on Days 1-3 between 3 and 4 hours after dosing).
Irritation: Once daily on Days 1-6 (on Days 1 - 3 immediately after dosing) according to the following numerical scoring system. Furthermore, a description of all other (local) effects was recorded.

Grading Irritation Reactions:
Erythema and eschar formation:
0: No erythema
1: Very slight erythema (barely perceptible)
2: Well-defined erythema
3: Moderate to severe erythema (beet redness) to slight eschar formation (injuries in depth)
4: Severe erythema (beet redness) to eschar formation preventing grading of erythema

Oedema formation:
0: No oedema
1: Slight oedema (barely perceptible)
2: Moderate oedema
3: Severe oedema

Necropsy: All animals were subjected to necropsy for gross macroscopic examination.

Positive control substance(s):

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

Statistics:

Not performed.

Results and discussion

Positive control results:

The six-month reliability check with Alpha-hexylcinnamicaldehyde indicates that the Local Lymph Node Assay as performed at NOTOX is an appropriate model for testing for contact hypersensitivity. See attached document 'Reliability check'.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: The SI values calculated for the substance concentrations 10, 25 and 40% were 1.3, 0.7 and 1.1 respectively.

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: Mean DPM/animal values for the experimental groups treated with test substance concentrations 10, 25 and 40% were 487, 263 and 404 DPM respectively. The mean DPM/animal value for the vehicle control group was 379 DPM.

Any other information on results incl. tables

Tables and figures of the Pre-screen test and Main study have been included in the attached document "LLNA tables and figures".

Results Pre-screen test:

Variations in ear thickness during the observation period were less than 25% from Day 1 pre-dose values. No signs of systemic toxicity were observed in any of the animals examined. White remnants of the test substance were present among the animals between Days 1 and 5, which prevented scoring for erythema after dosing on Days 1-3. No erythema was observed prior to dosing on Days 2 and 3. Based on these results, the highest test substance concentration selected for the main study was a 40% concentration.

Other results - main study:

White remnants of the test substance were present on both ears of all animals at a 10, 25 and 40% concentration between Days 1 and 4, which prevented scoring for erythema after dosing at the 25 and 40% concentration between Days 1-3.No oedema was observed in any of the animals examined.

All auricular lymph nodes of the animals of the experimental and control groups were considered normal in size. No macroscopic abnormalities of the surrounding area were noted in any of the animals.

 

Body weights and body weight gain of experimental animals remained in the same range as controls over the study period. The slight body weight loss, noted in several animals, was considered not toxicologically significant.

    

No mortality occurred and no symptoms of systemic toxicity were observed in the animals of the main study.

List of protocol deviations

1) On Days 2 and 3, scoring for irritation reactions was also conducted prior to dosing.

Evaluation: The additional scoring occasion provided additional information. On Day 1,scoring for erythema after dosing could not be conducted due to white test substance remnants. On Days 2 and 3, scoring for erythema could be conducted prior to dosing (without cleaning the ears), but not after dosing due to white test substance remnants. 2) Oedema was also scored on all occasions. Evaluation: additional information. The study integrity was not adversely affected by the deviations.

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Since there was no indication that the test substance elicits an SI = 3 when tested up to the maximum feasible concentration of 40%, Melam CAS 3576-88-3 was considered not to be a skin sensitizer. It was established that the EC3 value (the estimated test substance concentration that will give a SI =3) (if any) exceeds 40%.
Melam does not have to be classified and has no obligatory labelling requirement for sensitization by skin contact according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2007) and the Regulation (EC) No 1272/2008 on classification, labelling and packaging of substances and mixtures.

Executive summary:

Assessment of Contact Hypersensitivity to Melam CAS 3576-88-3 in the Mouse (Local Lymph Node Assay, 5 females/dose) was conducted according to OECD 429 guidelines and GLP principles.

Since there was no indication that the test substance elicits an SI = 3 when tested up to the maximum feasible concentration of 40%, Melam CAS 3576-88-3 was considered not to be a skin sensitizer. It was established that the EC3 value (the estimated test substance concentration that will give a SI =3) (if any) exceeds 40%.

Melam does not have to be classified and has no obligatory labelling requirement for sensitization by skin contact according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2007) and the Regulation (EC) No 1272/2008 on classification, labelling and packaging of substances and mixtures.