Neodymium(3+) acetate

Endpoint summary

Description of key information

Under the conditions of the study the test material does not cause sensitisation.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

16 January 2017 to 16 February 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The rare earth substances are known to give false positives in the LLNA studies. The Maximisation study was therefore deemed to be more appropriate for investigating the skin sensitisation potential of this substance.

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Batch No.of test material: NDAC16-44
- Expiration date of the lot/batch: 14 December 2017:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: For the purpose of the study, the test material was used freshly prepared in olive oil for the intradermal injections and in liquid paraffin for the topical applications. These vehicles were chosen as they produced the most suitable formulation at the required concentration. The preparation of the test material at 5% olive oil (w/w) was a yellowish homogeneous suspension and the preparation of the test material at 50% in liquid paraffin (w/w) was a purple homogeneous suspension.

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Females nulliparous and non-pregnant: Yes
- Age at study initiation: 3 to 4 weeks old
- Weight at study initiation: 253 to 289 g
- Housing: In groups of up to 3 in polycarbonate containers fitted with a stainless steel lid
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: A minimum of 5 days

ENVIRONMENTAL CONDITIONS
- Temperature: 19 to 25 °C
- Humidity: 30 to 70 %
- Air changes: At least ten per hour
- Photoperiod (hrs dark / hrs light): Twelve hours of continuous light from 07.00 to 19.00 and twelve hours of darkness.

Route:

other: Intredermal and Topical

Vehicle:

other: Olive oil (intradermal) and Paraffin oil (topical)

Concentration / amount:

Intradermal: 5 %/ 0.1 mL
Topical: 50 %/ 0.5 mL

Day(s)/duration:

Intradermal induction took place on Day 0. On Day 8, animals received a topical induction application which was covered for 48 hours.

Adequacy of induction:

non-irritant substance, but skin pre-treated with 10% SDS

No.:

#1

Route:

other: Topical

Vehicle:

other: Paraffin oil

Concentration / amount:

50 and 25 %/ 1 sample cup

Day(s)/duration:

On day 21 the challenge dose was applied for 24 hours

Adequacy of challenge:

not specified

No. of animals per dose:

5 animals in the control goup, 10 animals in the treated group

Details on study design:

RANGE FINDING TESTS:
- Determination by intradermal injection of the Maximal Non Necrotizing Concentration (MNNC)
Two animals received a volume of 0.1 mL of the test material, on both sides of the spine, at 4 concentrations: diluted at 5%, 2%, 1% and 0.5% in olive oil view to determine the MNNC. A macroscopic evaluation of the cutaneous reactions was conducted 24 hours after the injections.
- Determination by topical application of the Pre-Maximal Non Irritant Concentration (Pre-MNIC)
The test material was applied on the dorso-lumbar zone of two guinea pigs shorn beforehand, with occlusive dressing for 24 hours, at 4 different concentrations: diluted at 50%, 30%, 20% and 10% in liquid paraffin. After the removal of the occlusive dressing, the treated areas were rinsed with liquid paraffin. A macroscopic evaluation of the cutaneous reactions was conducted 24 hours after removal of the dressing.
- Determination by topical application of the Maximal Non Irritant Concentration (MNIC)
Three guinea pigs were treated according to the same treatment as animals from GROUP 1 (control) for the induction phase (i.e. olive oil and liquid paraffin). During the challenge phase, the animals were treated with the test material placed onto the selected treatment sites and covered with an occlusive dressing for a period of 24 hours at 4 different concentrations: diluted at 50%, 40%, 30% and 20% in liquid paraffin. After the removal of the occlusive dressing, the treated areas were rinsed with liquid paraffin. A macroscopic evaluation of the cutaneous reactions was conducted 24 and 48 hours after removal of the occlusive dressing.

MAIN STUDY

A.INDUCTION EXPOSURE
- Intradermal Induction:
Day 0: After shearing the scapular zone, three pairs of intradermal injections (ID) of 0.1 mL were performed on the scapular zone in such a way as an injection on each pair is placed to either side of the spine as follows:
GROUP 1 (control):
-2 ID: Freund’s Complete Adjuvant diluted at 50% in olive oil
-2 ID: olive oil
-2 ID: a mixture with equal volumes v/v: Freund’s Complete Adjuvant at 50% and olive oil
GROUP 2 (Treated):
-2 ID: Freund’s Complete Adjuvant diluted at 50% in olive oil
-2 ID: test material at 5% in olive oil
-2 ID: a test mixture in equal volumes v/v: Freund’s Complete Adjuvant at 50% and the test material at 10% in olive oil

- Topical Induction:
Day 7: The scapular zone of all the animals in each group, shorn beforehand, was brushed with a solution of sodium lauryl sulfate at 10% in thick vaseline, in order to create a local irritation.
Day 8: A topical application under occlusive dressing (25mm x 25mm non-woven swab of 4-layer patch held in contact with the skin by means of 50 mm wide hypoallergenic adhesive tape) for 48 hours was performed on the injection sites of each animal.
GROUP 1 (control): 0.5 mL of liquid paraffin.
GROUP 2 (treated): 0.5 mL of the test material at 50% in liquid paraffin.

B. CHALLENGE EXPOSURE
Day 21: The experimental procedure of this phase was identical for both groups 1 (Control) and 2 (Treated) submitted to this experimentation: on the previously shorn dorso-lumbar zone, an application, under occlusive dressing, was performed for 24 hours: 1 sample cup containing the test material diluted at 50% (MNIC) and 1 sample cup containing the test material diluted at 25% in liquid paraffin (1/2 MNIC).
Day 22: The treated areas were rinsed with liquid paraffin after the removal of the semi-occlusive dressing. Residue of product not preventing the erythema quotation was noted.
Day 23: 1st reading time – 24 hours after the patch removal.
Day 24: 2nd reading time – 48 hours after the patch removal.

INTERPRETATION OF RESULTS
The test material will be regarded as a sensitiser if 30% or more of the test animals show a sensitisation response.

Challenge controls:

No, the experimental procedure of this phase was identical for both groups 1 (Control) and 2 (Treated).

Positive control substance(s):

yes

Remarks:

α-hexylcinnamaldehyde (HCA)

Positive control results:

Under the experimental conditions, the reference substance a-Hexylcinnamaldehyde must be classified in category 1 “Skin sensitisation” sub-category 1B in accordance with the Regulation EC No. 1272/2008 on classification, labelling and packaging of substances and mixtures. The signal word “Warning” and hazard statement H317 “May cause an allergic skin reaction” are required.

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

25 / 50 %

No. with + reactions:

0

Total no. in group:

10

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

25 / 50 %

No. with + reactions:

0

Total no. in group:

10

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

25 / 50 %

No. with + reactions:

0

Total no. in group:

5

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

25 / 50 %

No. with + reactions:

0

Total no. in group:

5

Preliminary studies

- MNNC determination:

24 hours after the injections, no cutaneous reaction was noted whatever the tested concentrations. Therefore the first induction of Group 2 was carried out by intradermal injection at the maximal non necrosing concentration of 5%.

- Pre MNIC determination:

24 hours after the removal of the occlusive dressings, no cutaneous reaction was noted whatever the tested concentrations. In view of these results, the concentration selected was 50% for the 2nd induction of the Group 2 and the MNIC determination began at the concentration of 50%.

- MNIC determination:

24 and 48 hours after the removal of the occlusive dressings, no cutaneous reaction was noted whatever the tested concentration. In view of this result, the concentrations selected were 50% (MNIC) and 25% (1/2 MNIC).

 

Main study

- Induction phase Group 2:

No cutaneous reaction was noted in the animals 24 hours after the first induction. A scab was noted in three animals (3/10) and dryness of the skin was noted in seven animals (7/10) 24 hours after the second induction.

- Induction phase Group 1:

No cutaneous reaction was noted 24 hours after the first induction. A scab was noted in one animal (1/5) and dryness of the skin was noted in four animals (4/5) 24 hours after the second induction.

- Challenge phase Groups 1 & 2:

Overall results of the challenge phase with the test material (readings at 24 and 48 hours) are given in Table 1. In the treated group (treatment dose of 50%), no macroscopic cutaneous reactions attributable to allergy were noted after the challenge phase. In the control group (associated with the treatment dose of 50%), no macroscopic cutaneous intolerance reactions were recorded after the challenge phase. In the treated group (treatment dose of 25%), no macroscopic cutaneous reactions attributable to allergy were noted after the challenge phase. In the control group (associated with the treatment dose of 25%), no macroscopic cutaneous intolerance reactions were recorded after the challenge phase.

- Weight evolution

No abnormality was recorded in the body weight gain of both groups.

- Mortality

No mortality was registered during the main test.

Table 1: Macroscopic evaluation (readings at 24 and 48 hours) of cutaneous reactions

Groups	Reading time	Concentrations	Incidence				% of positive responses≥1	% of animal sensitised
			0	1	2	3
Group 1 Control	24 h	50 %	5	0	0	0	0	-
	48 h	50 %	5	0	0	0	0	-
	24 h	25 %	5	0	0	0	0	-
	48 h	25 %	5	0	0	0	0	-
Group 2 Treated	24 h	50 %	10	0	0	0	0	0
	48 h	50 %	10	0	0	0	0	0
	24 h	25 %	10	0	0	0	0	0
	48 h	25 %	10	0	0	0	0	0

 

Interpretation of results:

other: Not sensitising in accordance with EU criteria

Conclusions:

Under the conditions of the study, the test material is not considered to be a skin sensitiser.

Executive summary:

The study set out to evaluate the possible sensitisation of the test material using the guinea pig maximisation test. The study was performed in accordance with the standardised guidelines OECD 406 and EU method B.6, under GLP conditions.

According the results of the pre-tests, the induction phase (intradermic injection at 5% and topical application at 50%) was conducted with the test material to 10 Guinea pigs with a 10-day rest phase.

Animals were treated with an intradermal injection of 0.1 mL of 5% test material in olive oil or olive oil only for the control on day 0. On day 7 the treatment zone was brushed with sodium lauryl sulphate at 10% in thick Vaseline to create irritation. On day 8 the topical induction was applied under an occlusive dressing, this was 0.5 mL of 50% test material in liquid paraffin or liquid paraffin only for the control group. The challenge phase was conducted on day 21, it was placed under an occlusive dressing for 24 hours. The challenge consisted of a single topical application of the test material diluted at 50% and 25% in liquid paraffin. The challenge was observed at 24 and 48 hours post patch removal.

In the treated group (treatment dose of 50%), no macroscopic cutaneous reactions attributable to allergy were noted after the challenge. In the control group (associated with the treatment dose of 50%), no macroscopic cutaneous intolerance reactions were recorded after the challenge phase.

In the treated group (treatment dose of 25%), no macroscopic cutaneous reactions attributable to allergy were noted after the challenge phase. In the control group (associated with the treatment dose of 25%), no macroscopic cutaneous intolerance reactions were recorded after the challenge phase.

Under the conditions of the study the test material does not cause sensitisation and does not have to be classified in category 1 as a skin sensitiser, in accordance with the Regulation EC No. 1272/2008 on classification, labelling and packaging of substances and mixtures.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The study set out to evaluate the possible sensitisation of the test material using the guinea pig maximisation test. The study was performed in accordance with the standardised guidelines OECD 406 EU method B.6, under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

According the results of the pre-tests, the induction phase (intradermic injection at 5% and topical application at 50%) was conducted with the test material to 10 Guinea pigs with a 10-day rest phase.

Animals were treated with an intradermal injection of 0.1 mL of 5% test material in olive oil or olive oil only for the control on day 0. On day 7 the treatment zone was brushed with sodium lauryl sulphate at 10% in thick Vaseline to create irritation. On day 8 the topical induction was applied under an occlusive dressing, this was 0.5 mL of 50% test material in liquid paraffin or liquid paraffin only for the control group. The challenge phase was conducted on day 21, it was placed under an occlusive dressing for 24 hours. The challenge consisted of a single topical application of the test material diluted at 50% and 25% in liquid paraffin. The challenge was observed at 24 and 48 hours post patch removal.

In the treated group (treatment dose of 50%), no macroscopic cutaneous reactions attributable to allergy were noted after the challenge. In the control group (associated with the treatment dose of 50%), no macroscopic cutaneous intolerance reactions were recorded after the challenge phase.

In the treated group (treatment dose of 25%), no macroscopic cutaneous reactions attributable to allergy were noted after the challenge phase. In the control group (associated with the treatment dose of 25%), no macroscopic cutaneous intolerance reactions were recorded after the challenge phase.

Under the conditions of the study the test material does not cause sensitisation and does not have to be classified in category 1 as a skin sensitiser, in accordance with the Regulation EC No. 1272/2008 on classification, labelling and packaging of substances and mixtures.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

In accordance with the criteria for classification as defined in Annex I, Regulation (EC) No 1272/2008, the substance does not require classification with respect to skin sensitisation.