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EC number: 232-221-5 | CAS number: 7790-76-3
Skin sensitisation
Administrative data
- Endpoint:
- skin sensitisation: in vivo (non-LLNA)
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 08 Jul - 15 Aug 2014
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
Data source
Reference
- Reference Type:
- study report
- Title:
- Unnamed
- Year:
- 2 014
- Report date:
- 2014
Materials and methods
Test guideline
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 406 (Skin Sensitisation)
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Type of study:
- guinea pig maximisation test
- Justification for non-LLNA method:
- Dicalcium pyrophosphate is an inorganic salt of the alkaline earth metal calcium and pyrophosphate (diphosphate, a condensed orthophosphate). The water solubility of dicalcium pyrophosphate is low (0.255 mg/L). Dermal absorption is therefore anticipated to be low (ECHA Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7c: Endpoint specific guidance. Version 2.0, November 2014). Based on the identity/chemical structure and physicochemical properties, testing for skin sensitisation by means of a Local Lymph Node Assay (OECD 429) is considered to be inappropriate, as it may underestimate the skin sensitising potential of the test substance, leading to a false negative result, due to a low dermal absorption and hence low exposure. For this reason, the Guinea Pig Maximization Test, which involves intradermal injection of the test substance for induction thus ensuring exposure beneath the skin surface, is considered to be the most appropriate method for assessing the skin sensitising potential of this particular substance.
Test material
- Reference substance name:
- Dicalcium pyrophosphate
- EC Number:
- 232-221-5
- EC Name:
- Dicalcium pyrophosphate
- Cas Number:
- 7790-76-3
- Molecular formula:
- Ca2O7P2
- IUPAC Name:
- dicalcium pyrophosphate
- Test material form:
- solid: particulate/powder
Constituent 1
In vivo test system
Test animals
- Species:
- guinea pig
- Strain:
- Dunkin-Hartley
- Sex:
- female
- Details on test animals and environmental conditions:
- TEST ANIMALS
- Source: Charles River, Germany
- Age at study initiation: 4-6 weeks
- Weight at study initiation: 300.9-337.5 g
- Housing: test animals were housed in groups of up to ten.
- Diet: commercial feeding mixture (Mühle Knull, Rostock, Germany), ad libitum
- Water: tap water (drinking quality, supplemented with 1 g/L vitamin C)
- Acclimation period: at least 5 days
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ± 3 °C
- Humidity (%): 30-70
- Air changes (per hr): 16
- Photoperiod (hrs dark / hrs light): 12/12
Study design: in vivo (non-LLNA)
Inductionopen allclose all
- Route:
- intradermal
- Vehicle:
- water
- Concentration / amount:
- 1%
- Day(s)/duration:
- 7
- Adequacy of induction:
- highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
- Route:
- epicutaneous, occlusive
- Vehicle:
- water
- Concentration / amount:
- 100%
- Day(s)/duration:
- 2
- Adequacy of induction:
- highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Challenge
- No.:
- #1
- Route:
- epicutaneous, occlusive
- Vehicle:
- water
- Concentration / amount:
- 100%
- Day(s)/duration:
- 1
- Adequacy of challenge:
- highest non-irritant concentration
- No. of animals per dose:
- 5 (negative control)
10 (test groups) - Details on study design:
- RANGE FINDING TESTS:
The appropriate test material concentrations for intradermal and epicutaneous induction and epicutaneous challenge exposures were determined in a preliminary test using 6 additional FCA-treated animals.
For intradermal exposure, animals were given the test material at 5, 2.5, 1 and 0.5% suspensions in water by intradermal injections (0.1 mL). Animals were examined for signs of skin irritation at 24 and 48 h post-injection according to the Magnusson Kligman grading scale.
For topical exposure, animals were treated with the test material at 100, 50 and 25% in distilled water for 24 h under occlusive conditions. Irritation responses were assessed at 24 and 48 h after patch and substance removal.
Based on the results of the preliminary test (see Table 1), in the main test, 1% test material in water and 100% test material moistened with water were selected for intradermal and topical treatment, respectively.
MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (intradermal and epicutaneous, respectively)
- Exposure period: single injection (intradermal) and 48 h (epicutaneous)
- Test group:
Intradermal (3 pairs of injections, 0.1 mL):
Injection 1: 1:1 mixture (v/v) FCA/water
Injection 2: 1% test substance in water
Injection 3: 1% test substance in a 1:1 mixture (v/v) FCA/water
- Negative control group:
Intradermal (3 pairs of injections, each 0.1 mL):
Injection 1: 1:1 mixture (v/v) FCA/water
Injection 2: water
Injection 3: 1:1 mixture (v/v) FCA/water
Epicutaneous:
- Test group: test substance at 100%
- Negative control: water
- Site: scapular region (intradermal + epicutaneous)
- Frequency of applications: single
- Duration: Days 0-8 (on Day 6, one day prior to epicutaneous induction, the shorn skin of all animals in each group was treated with 0.5 mL of 10% sodium lauryl sulphate vaseline, in order to create a local irritation).
B. CHALLENGE EXPOSURE
- No. of exposures: 1 (challenge)
- Day(s) of challenge: 21 (challenge)
- Exposure period: 24 h
- Test groups: 100 % test substance moistened with water
- Control group: 100 % test substance moistened with water
- Site: flank region
- Concentrations: 100 %
- Evaluation (hr after challenge): 48 and 72 h - Positive control substance(s):
- yes
- Remarks:
- hexyl cinnamic acid (CAS No 101-86-0, routinely evaluated every 6 month at challenge concentrations of 55% in vaseline)
Results and discussion
- Positive control results:
- Hexyl cinnamic acid (at challenge concentration of 55% in vaseline) induced skin sensitisation reactions in 90% of the treated animals.
In vivo (non-LLNA)
Resultsopen allclose all
- Key result
- Reading:
- 1st reading
- Hours after challenge:
- 24
- Group:
- negative control
- Dose level:
- induction (intradermal): 0%; induction (epicutaneous): 0%; challenge: 100%
- No. with + reactions:
- 0
- Total no. in group:
- 5
- Clinical observations:
- No visible symptoms during observation.
- Remarks on result:
- no indication of skin sensitisation
- Key result
- Reading:
- 2nd reading
- Hours after challenge:
- 48
- Group:
- negative control
- Dose level:
- induction (intradermal): 0%; induction (epicutaneous): 0%; challenge: 100%
- No. with + reactions:
- 0
- Total no. in group:
- 5
- Clinical observations:
- No visible symptoms during observation.
- Remarks on result:
- no indication of skin sensitisation
- Reading:
- 1st reading
- Hours after challenge:
- 24
- Group:
- test chemical
- Dose level:
- induction (intradermal): 1%; induction (epicutaneous): 100%; challenge: 100%
- No. with + reactions:
- 0
- Total no. in group:
- 10
- Clinical observations:
- No visible symptoms during observation.
- Remarks on result:
- no indication of skin sensitisation
- Reading:
- 2nd reading
- Hours after challenge:
- 48
- Group:
- test chemical
- Dose level:
- induction (intradermal): 1%; induction (epicutaneous): 100%; challenge: 100%
- No. with + reactions:
- 0
- Total no. in group:
- 10
- Clinical observations:
- No visible symptoms during observation.
- Remarks on result:
- no indication of skin sensitisation
Any other information on results incl. tables
Animal weights
Table 3: Individual animal weights (g) at start / test end (test group)
Animal |
Test start |
Test end |
Body weight change |
1 |
337.5 |
417.5 |
80.0 |
2 |
315.5 |
383.8 |
68.3 |
3 |
317.0 |
394.6 |
77.6 |
4 |
334.6 |
435.9 |
101.3 |
5 |
316.0 |
390.4 |
74.4 |
6 |
301.3 |
377.8 |
76.5 |
7 |
300.9 |
383.3 |
82.4 |
8 |
318.6 |
401.3 |
82.7 |
9 |
334.8 |
445.1 |
110.3 |
10 |
302.1 |
356.5 |
54.4 |
Individual weight of control group
Table 4: Individual animal weights (g) at test start and at test end (control group)
Animal |
Test start |
Test end |
Body weight change |
K1 |
318.0 |
362.9 |
44.9 |
K2 |
333.6 |
399.4 |
65.8 |
K3 |
335.6 |
406.8 |
71.2 |
K4 |
313.5 |
380.2 |
66.7 |
K5 |
309.0 |
376.0 |
67.0 |
Table 5: Skin reactions of test animals after treatment with the test material
Animal |
Numerical grading after |
|
24 h |
48 h |
|
1 |
0 |
0 |
2 |
0 |
0 |
3 |
0 |
0 |
4 |
0 |
0 |
5 |
0 |
0 |
6 |
0 |
0 |
7 |
0 |
0 |
8 |
0 |
0 |
9 |
0 |
0 |
10 |
0 |
0 |
Table 6: Skin reactions of control animals after treatment with the test material
Animal |
Numerical grading after |
|
24h |
48h |
|
K1 |
0 |
0 |
K2 |
0 |
0 |
K3 |
0 |
0 |
K4 |
0 |
0 |
K5 |
0 |
0 |
Table 7: Skin reactions of animals after challenge treatment with HCA 55 % in vaseline
Animal |
Numerical grading after |
|
24 h |
48 h |
|
1 |
1 |
1 |
2 |
0 |
0 |
3 |
1-2 |
1-2 |
4 |
1 |
1 |
5 |
1-2 |
2 |
6 |
1 |
1 |
7 |
1-2 |
1-2 |
8 |
0-1 |
1 |
9 |
1-2 |
1 |
10 |
1 |
1 |
Applicant's summary and conclusion
- Interpretation of results:
- GHS criteria not met
- Conclusions:
- The test material did not induce any skin reactions in intradermally and topically induced guinea pigs after challenge treatment. Therefore, the material does not fulfil the criteria for classification according to Regulation (EC) No 1272/2008 (CLP) and the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), and is thus considered to be not skin sensitising.
CLP: not classified
GHS: not classified
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