Bis(acetato-O)hydroxyaluminium

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10 August 2017 - 13 November 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

1992

Deviations:

no

Test guideline 2

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 test substance is a metal salt for which the local lymph node assay (LLNA) is not recommended. It is known that the LLNA produces false negative results for metal salts (NTP, 1999, NIH Publication No. 99-4494). Therefore the guinea pig maximisation test (GPMT) was performed instead of the LLNA.

Test material

Test material information

Constituent 1

Reference substance name:

Aluminum hydroxide diacetate monohydrate

Cas Number:

80164-67-6

Molecular formula:

C4H7AlO5 H2O

IUPAC Name:

Aluminum hydroxide diacetate monohydrate

Test material form:

solid

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: ENVIGO RMS B.V., Kreuzelweg 53, 5961 NM Horst, Netherlands
- Weight at study initiation: 258 – 428 g
- Housing: 5 animals/cage
- Diet: S & K LAP rabbit diet, ad libitum.
- Water: tap water from municipal supply as for human consumption, containing 50 mg/100 mL ascorbic acid, ad libitum.
- Acclimation period: 14 days
- Indication of any skin lesions: none

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ± 3
- Humidity (%): 30 - 70
- Air changes (per hr): > 10
- Photoperiod (hrs dark / hrs light): 12 / 12

Study design: in vivo (non-LLNA)

Induction

Route:

intradermal and epicutaneous

Vehicle:

physiological saline

Concentration / amount:

intra-dermal: 5 % / 0.1 mL/site; dermal: 40 % / 0.5 mL

Day(s)/duration:

intra-dermal: day 1 / 24 hours; dermal: day 8 / 48 hours

Challenge

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

physiological saline

Concentration / amount:

40 % (w/v)

Day(s)/duration:

two weeks after the dermal treatment / 24 hours

No. of animals per dose:

test group: 20, control group: 10

Details on study design:

RANGE FINDING TESTS: A preliminary dose range finding study was performed to select the doses of the main study.

MAIN STUDY

A. INDUCTION EXPOSURE (Intra-dermal Induction Exposure):
- Test group:
2 injections with 0.10 mL of Freund's Adjuvant mixed with physiological saline (1:1 v/v),
2 injections with 0.10 mL of the test item (5 %) homogenized physiological saline,
2 injections with 0.10 mL of test item (5 %), formulated in a 1:1 (v/v) mixture of Freund's Adjuvant and physiological saline
- Control group:
2 injections with 0.1 mL mix of Freund's Adjuvant and physiological saline (1:1)(v/v),
2 injections with 0.1 mL of physiological saline,
2 injections with 0.1 mL of 50 % v/v formulation of the physiological saline in a 1:1 mixture (v/v) Freund's Adjuvant and physiological saline.
- Exposure period: 24 hours

B. INDUCTION EXPOSURE (Dermal Induction Exposure):
Six days after the intra-dermal injections, in all animals the test area was painted with 0.5 mL of 10 % sodium dodecyl sulphate in Vaseline 24 h prior to topical induction application, in order to create a local irritation.
- Test group:
Approximately 24 hours after the painting, the test animals were exposed to test item. Closed patches were applied in the following manner: in case of the test animals a 5x5 cm patch of sterile gauze was saturated with 0.5 mL test item at concentration of 40 % and placed over the injection sites of the animals. These gauze patches were kept in contact with the skin by a patch with a surrounding adhesive hypoallergenic plaster. The exposed areas were covered for 48 hours with 4 layers of porous gauze pads and fully occlusive foil fastened with "Leucoplast" (Closed Patch Test). After the dermal induction exposition the rest of the test item was removed with water of body temperature.
- Control group:
Approximately 24 hours after the painting, the control animals were treated with physiological saline, as vehicle. All control animals were treated dermally with 0.50 mL of vehicle and the dressing was prepared and applied as for the test animals.

C. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day of challenge: 14 days after the dermal treatment the animals were exposed to the challenge dose.
- Exposure period: 24 hours
- Test group and Control group: 24 hours before the challenge treatment the left and the right flank areas (5x5 cm) of each animal were prepared for application. The hair was clipping from an approximate area 6x8 cm on the left and right flank of each animals. The challenge was performed as a dermal exposure (Closed Patch Test). Left shaved flank areas of the animals (both the test and the control) were treated with 0.5 mL of the test item (at concentration of 40 %). The right shaved flank areas were treated with 0.5 mL of vehicle, in all cases.
- Site: left and right flank
- Concentrations: 40 %
- Evaluation: 24 and 48 hours after patch removal

Positive control substance(s):

no

Results and discussion

In vivo (non-LLNA)

Results

Results 1

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

40 %

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

no clinical signs

Remarks on result:

no indication of skin sensitisation

Results 2

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

40 %

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

no clinical signs

Remarks on result:

no indication of skin sensitisation

Results 3

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

no clinical signs

Remarks on result:

no indication of skin sensitisation

Results 4

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

no clinical signs

Remarks on result:

no indication of skin sensitisation

Results 5

Group:

positive control

Remarks on result:

not measured/tested

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

It can be assumed that the experimental result of the test item is also valid for the anhydrous test item. No signs of contact sensitisation were detected in guinea pigs exposed to the test item. In the control and treated animals the means of the scores of dermal reaction were 0.00 according to the 24 and 48-hour results of the challenge phase. Therefore, the test item is not classified as sensitiser.

Executive summary:

A skin sensitisation study was performed according to Magnusson-Kligman method using Freund's complete adjuvant technique to evaluate the sensitisation potential of test item. 20 test animals were subjected to sensitisation procedures with two routes of administration for the induction phase, i.e. an intra-dermal treatment and a topical application. The test item was used at concentration of 5 % for intra-dermal injections and at concentration of 40 % for dermal sensitisation treatment. Two weeks following the last induction exposure, a challenge dose (at concentration of 40 %) was administered to check elicitation. Challenge was performed by dermal application of the test item for 24 hours (Closed Patch Test). 10 control guinea pigs were simultaneously exposed to vehicle during the induction phase and they were treated with the test item (at concentration of 40 %) only for the challenge phase, i.e. the elicitation phase.

No signs of contact sensitisation were detected in guinea pigs exposed to the test item. In the control and treated animals the means of the scores of dermal reaction were 0.00 according to the 24 and 48-hour results of the challenge phase. Therefore, the test item is not classified as sensitiser. It can be assumed that the experimental result of the test item is also valid for the anhydrous test item.