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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
GLP compliance:
yes (incl. certificate)
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): NX-4708, NX2023
- Name of test material (as cited in study report): Distilled CNSL (distilled grade)
- Lot/batch No.: NX-4708 and NX-2023

In vivo test system

Test animals

Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan UK Limited
- Age at study initiation: 8 - 12 weeks old
- Weight at study initiation: 15 to 23 g
- Housing: suspended solid-floor polypropylene cages
- Diet (e.g. ad libitum): Certified rat and mous diet ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 5 days


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

Study design: in vivo (LLNA)

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
10%, 25% and 50% for screening test.
No. of animals per dose:
4
Details on study design:
RANGE FINDING TESTS:
- Compound solubility: Soluble
- Irritation: Mild or moderate redness to the ears and neck was noted in animals tested with the undiluted test material, or at 50 or 25%.


MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: OECD 429
- Criteria used to consider a positive response: Stimulation Index of 3.0 or greater


TREATMENT PREPARATION AND ADMINISTRATION: NX-4708 and NX-2023 were used undiluted and freshly prepared as a solution in acetone:olive oil 4:1. This vehicle was chosen as it produced the highest concentration that was suitable for dosing. Two groups of four mice were treated with either NX-4708 or NX-2023 at a concentration of 10% v/v in acetone/olive oil 4:1. The mice were administered a daily application of 25 µl of each test material to the dorsal surface of each ear for three consecutive days. The test material formulations were administered using an automatic micropipette and spread over the dorsal surface of the ear using the tip of the pipette.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
Use of statistics not indicated.

Results and discussion

Positive control results:
Concentration: 15%
Stimulation index: 10.91
Result: positive

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Remarks on result:
other: Vehicle: N/A NX-4708: 29.29 NX-2023: 30.90
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: Vehicle: 4871.26 NX-4708: 142691.40 NX-2023: 150509.50

Any other information on results incl. tables

Table 1 Clinical observations, bodyweight and mortality data - preliminary screening test - NX-4708
Concentration (% v/v) in acetone/olive oil 4:1 Animal number  Bodyweight change (g) Day 
      1  6  1     2     3     4  6
      Pre dose  Post dose
Pre dose
 Post dose  Pre dose  Post dose              
100  S-1  20 
50  S-2  20 
25  S-3  17 
10  S-4  19  20 

Read across justification

The read across substance is Cashew (Anacardium occidentale) Nutshell Extract, Decarboxylated, Distilled (“Distilled Grade”). The study for distilled grade is considered relevant for read across to distillation residue grade since the two substances: •Contain the same constituents (cardanol, cardol, 2-methyl cardol, C13 and unidentified phenolics, C17 phenolics and polymeric species), generally in similar proportions. •Have similar physico-chemical properties in terms of their water solubility, vapour pressure and octanol-water partition coefficient. Cashew (Anacardium occidentale) Nutshell Extract, Decarboxylated, Distilled (“Distilled Grade”) has a higher proportion of lower molecular weight, more potentially toxicologically active components, (principally cardanol) and lower proportion of more inert polymeric species compared to Distillation Residue Grade. The relative typical proportions of the cardanol and polymeric species in Distilled and Distillation Residue Grades are 78% versus 35% and 2% versus 50% respectively. Therefore, it is considered that distilled grade has the potential to exert greater toxicity within the group of distilled, technical and distilled residue grades (see Section 3.1 - Technological Process) for endpoints relevant to human health and environmental effects. On this basis within the group of distilled, technical and distilled residue grades, the substance Cashew (Anacardium occidentale) Nutshell Extract, Decarboxylated, Distilled represents the potentially most (eco)toxicologically active form.

Applicant's summary and conclusion

Interpretation of results:
sensitising
Remarks:
Migrated information EU
Conclusions:
A positive result was obtained in a well-conducted LLNA, indicating that Cashew Nutshell Extract, Decarboxylated, Distilled (Distilled Grade) is able to cause skin sensitisation. A similar conclusion is expected for Cashew Nutshell Extract, Decarboxylated, Distillation Residue (Distilled Residue Grade) based on the read-across justification.
Executive summary:

In a dermal sensitization study with Cashew Nutshell Extract, Decarboxylated, Distilled (Distilled Grade) in acetone/olive oil 4:1, four young adult CBA mice were tested using the LLNA method.  Mild redness to the eyes and neck were observed in test animals. No other clinical signs of toxicity were noted and mortality did not occur. Bodyweights of treated animals were comparable to that of controls.

 

Stimulation indexes of 29.29 and 30.90 were identified, for NX-4708 and NX-2023, respectively.  the EC3 value was not directly determined, however, 10% of test substance elicited a stimulation index of 30 (EC3 = % test substance required to elicit a stimulation index of 3).

This indicates that Cashew Nutshell Extract, Decarboxylated, Distilled (Distilled Grade) is a skin sensitiser category 1A. A similar conclusion is expected for Cashew Nutshell Extract, Decarboxylated, Distillation Residue (Distilled Residue Grade) based on the read-across justification.