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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
other: read across: supporting substances
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Materials and methods well described; results presented adequately in text, tables and figures. A second observation (72 hours after beginning of the challenge) was not performed. In accordance with Annex XI, point 1.5 (read-across) of Regulation (EC) No 1907/2006, results on magnesium alloys can be used in support of calcined dolomite, justified as follows: Magnesium may be released from both magnesium alloys and calcined dolomite in the form of Mg2+ ions, which is relevant for evaluation of the skin sensitisation potential. Thus, the results of this study are presented as supportive data for magnesium contained in calcined dolomite, by read-across from materials with similar physiological behaviour.

Data source

Reference
Reference Type:
publication
Title:
Evaluation of the skin sensitizing potential of biodegradable magnesium alloys
Author:
Witte, F. et al.
Year:
2007
Bibliographic source:
J. Biomed. Mater. Res. A. 86, 1041-1047
Report date:
2007

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
yes
Remarks:
see "rationale for reliability"
Qualifier:
according to guideline
Guideline:
EU Method B.6 (Skin Sensitisation)
Deviations:
yes
Remarks:
see "rationale for reliability"
Principles of method if other than guideline:
The test animals were initially exposed to the test substance by intradermal injection (day 0) and topical induction (day 7). Following a rest period of 14 days (induction period), during which an immune response may develop, the animals were exposed to a challenge dose. The extent and degree of skin reaction to the challenge exposure (patch removal after 24h) in the test animals were compared with that demonstrated by control animals which underwent sham treatment during induction and receive the challenge exposure (48 h after beginning of the challenge).
GLP compliance:
not specified
Type of study:
guinea pig maximisation test

Test material

Constituent 1
Reference substance name:
Different magnesium alloys (MgAl, MgLi4Al, MgY)
IUPAC Name:
Different magnesium alloys (MgAl, MgLi4Al, MgY)
Details on test material:
Name of test material (as cited in study report):
4 different magnesium alloys
(i) AZ31: MgAl (2.4-3.6 %), Zn (0.5-1.5 %), Mn (0.15-1 %), Si 0.1 %, Cu 0.1 % = Mg content between 96.8 and 93.7 % (w/w)
(ii) AZ91: MgAl (8.1-9.3 %), Zn (0.4-1 %), Mn (0.17-0.35 %), Si 0.2 % = Mg content between 91.1 and 89.2 % (w/w)
(iii) WE43: MgLi4Al (3.4-4.6 %), rare earth (1.8-3 %), Mn (min. 0.25 %), Zn (max. 0.22 %) = Mg content between 94.3 and 92 % (w/w)
(iv) LAE442: MgY (3.7-4.3 %), rare earth (2.4-4.4 %), Zr (0.4-1 %), Li 0.2 %, Mn 0.15 % = Mg content between 93.2 and 90 % (w/w)
Numbers following the letters represent the percentage of the element in the magnesium alloy displayed in % w/w

The test material AZ31 was obtained from Dead Sea Magnesium, Israel, the remaining alloys were purchased from Magnesium Elektron, UK.

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Winkelmann, Borchen, Germany
- Weight at study initiation: 400-550 g
- Housing: in pairs in clean plastic cages (55 x 32.8 x 19 cm³) on standard bedding
- Diet: ad libitum, standard pellets
- Water: ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature: 20 ± 3 °C
- Humidity: humidity of 30-70 %
- Photoperiod: 2 hours dark/light cycle
No further details are given.

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal and epicutaneous
Vehicle:
other: see "concentration"
Concentration / amount:
100 %:
All test items were tested both in dissolved and solid state parallel to positive and negative control substances. Therefore, the magnesium alloys were dissolved by boiling in 2 mol/L HCl solution and buffered with 1 mol/L NaOH solution at pH 5.5. The supernatants were microfiltrated and the ion metal content was confirmed by ICP-AES.
Challengeopen allclose all
Route:
epicutaneous, semiocclusive
Vehicle:
other: see "concentration"
Concentration / amount:
100 %:
All test items were tested both in dissolved and solid state parallel to positive and negative control substances. Therefore, the magnesium alloys were dissolved by boiling in 2 mol/L HCl solution and buffered with 1 mol/L NaOH solution at pH 5.5. The supernatants were microfiltrated and the ion metal content was confirmed by ICP-AES.
No. of animals per dose:
20 animals for each test substance; 10 with the solid material and 10 with the dissolved material. 15 animals in the negative control group and 15 animals in the positive control group.
Details on study design:
An intradermal test and an epicutaneous patch test were performed. The skin reaction was interpreted by qualitative grading of three independent observers immediately and 24 hours after patch removal. For grading of the skin reaction, the erythema classification according to the Magnusson-Kligman test was used. A skin reaction graded greater than zero was defined as erythema.

The test site was clipped for intradermal injection. For topical application, the hair was clipped and closely shaved. Cellulose filters (2 x 4 cm² and 2 x 2 cm²) were used as patches. Applied test patches were covered with overlapping pieces of impermeable plastic tape and fixed with 25 cm long strips of elastic tape bandage which was secured by twp pieces of tape.

Cutaneous biopsies were harvested 24 hours after patch removal and analysed for histomorphological criteria. Epidermis and dermis were included in cell counting and histomorphological analysis.
Challenge controls:
Negative control: Sodium lauryl sulfate
Preliminary test performed with all test items with one animal each; non-irritant concentrations were determined.
Positive control substance(s):
yes
Remarks:
hydroxy-cinnamon-aldehyde

Results and discussion

Positive control results:
All Guinea pigs exposed to the standard allergen showed persisting erythema for more than 24 hours after patch removal. One animal died during the challenge phase for reasons not related to the test, and one skin biopsy was lost because of technical problems. Histological analysis revealed all four criteria of allergy such as spongiosis, oedema, and diffuse as well as perivascular mononuclear infiltrates in 12 (92.3 %) of the remaining 13 biopsies. The positive control biopsies contained a mean of 52.7 basophile cells/400 leukocyte cells. Furthermore, in biopsies of the positive control group, a significantly higher number of basophile cells was found compared to the negative control group and all tested substances (p=0.001, ANOVA).

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
48
Group:
other: AZ91
Dose level:
dissolved test substance
No. with + reactions:
3
Total no. in group:
10
Clinical observations:
Mild skin reactions
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: other: AZ91. Dose level: dissolved test substance. No with. + reactions: 3.0. Total no. in groups: 10.0. Clinical observations: Mild skin reactions.
Reading:
1st reading
Hours after challenge:
0
Group:
other: AZ31
Dose level:
dissolved test substance
No. with + reactions:
1
Total no. in group:
10
Clinical observations:
Mild clinical skin response; 24 h after the patch was removed, all erythema had faded.
Remarks on result:
other: see Remark
Remarks:
Reading: 1st reading. . Hours after challenge: 0.0. Group: other: AZ31. Dose level: dissolved test substance. No with. + reactions: 1.0. Total no. in groups: 10.0. Clinical observations: Mild clinical skin response; 24 h after the patch was removed, all erythema had faded..
Reading:
1st reading
Hours after challenge:
48
Group:
positive control
No. with + reactions:
15
Total no. in group:
15
Clinical observations:
Persisting erythema
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: positive control. No with. + reactions: 15.0. Total no. in groups: 15.0. Clinical observations: Persisting erythema.
Reading:
1st reading
Hours after challenge:
48
Group:
negative control
No. with + reactions:
0
Total no. in group:
15
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: negative control. No with. + reactions: 0.0. Total no. in groups: 15.0.
Reading:
1st reading
Hours after challenge:
48
Group:
other: WE43 and LAE442
Dose level:
dissolved test substance
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
Remark: 10 per test substance (in total 20 animals)
Remarks on result:
other: see Remark
Remarks:
Reading: 1st reading. . Hours after challenge: 48.0. Group: other: WE43 and LAE442. Dose level: dissolved test substance. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: Remark: 10 per test substance (in total 20 animals).

Any other information on results incl. tables

Test results for all substances used as received.

Between 90 % (AZ31) and 100 % (AZ91) of the tested skin areas displayed erythema immediately after patch removal. However, after 24 hours the erythema remained in only 20 % of the AZ91 group and 11 % of the LAE442 group. To identify allergic erythema after 24 hours, dermal biopsies were taken. All biopsies exhibited significantly (p=0.001) less histomorphological criteria of allergenicity compared to the positive control group. In all biopsies no significant differences were found for basophile cells compared to the negative control. In the LAE442 group of the solid test substances, one animal died unrelated to the study conditions. Animals treated with AZ91and LAE442 which still had an erythema 24 hours after patch removal, showed no criteria of allergenicity in histomorphological analysis. No correlation was found between the cell count of eosinophiles and the concentration of aluminium in the test solutions (p>0.05).

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information
Conclusions:
The tested magnesium alloys (with a total magnesium content between 89.2 and 96.8 %) exhibit no sensitising potential compared to the control groups.