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Administrative data

Description of key information

There is no available data for magnesium hydrogenorthophosphate. Reliable data were used from the structural analogue pentacalcium hydroxide tris(orthophosphate) (CAS 12167 -74 -7).

Skin sensitistaion (RA 12167 -74 -7, OECD 406, RL1): not sensitisting

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
refer to analogue justification provided in IUCLID section 13
Reason / purpose:
read-across source
Positive control results:
Hexyl cinnamic acid (at challenge concentration of 55% in vaseline) induced skin sensitisation reactions in 90% of the treated animals.
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
induction (intradermal): 0%; induction (epicutaneoues): 0%, challenge 100%
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
no visible clinical symptoms over the period of 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 (epicutaneoues): 0%, challenge 100%
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
no visible clinical symptoms over the period of observation
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
100%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no visible clinical symptoms over the period of observation
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
100%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no visible clinical symptoms over the period of observation
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
55%
No. with + reactions:
9
Total no. in group:
10
Remarks on result:
positive indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
55%
No. with + reactions:
9
Total no. in group:
10
Remarks on result:
positive indication of skin sensitisation

Animal weights

Table 3: Individual animal weights (g) at start / test end (test group)

Animal

Test start

Test end

Body weight change

1

305.3

387.4

82.1

2

313.5

379.8

66.3

3

318.7

414.7

96.0

4

309.3

388.8

79.5

5

301.2

399.9

98.7

6

315.7

385.2

69.5

7

304.1

399.4

95.3

8

321.0

422.8

101.8

9

309.8

375.7

65.9

10

309.3

411.5

102.2

 

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

309.4

383.0

73.6

K2

300.9

376.1

75.2

K3

324.0

396.1

72.1

K4

327.1

408.5

81.4

K5

326.4

398.7

72.3

 

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

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 sensitizing.
Executive summary:

No skin senistisation properties are considered from the source study by Gruemmer, 2014 (GPMT). As explained in the justification for type of information, the differences in molecular structure between the target and the source are unlikely to lead to differences in the skin sensitisation potential.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

No studies are available with magnesium hydrogenorthophosphate (CAS 7757 - 87 -1). Reliable data is available for pentacalcium hydroxide tris(orthophosphate) (CAS 12167 -74 -7).

Pentacalcium hydroxide tris(orthophosphate) and magnesium hydrogenorthophosphate are structurally similar ionic compounds with the only differences being that calcium is replaced with magnesium. The phosphate groups are structurally identical between the two compounds and any skin sensitising potential will be the same. Magnesium and calcium are both alkali metals from group 2 and periods 3 and 4 of the periodic table, respectively and have only one oxidation state (+2). Magnesium and calcium are among the most abundant elements and are the important essential nutrients for higher plants, algae, animals and human. Both elements are similar in chemical nature and show the related metabolism and similar environmental behaviour. The differences between the two compounds will not have an impact on any skin sensitising potential and therefore, the result from the skin sensitisation study can reliably be read across to magnesium hydrogenorthophosphate.

 

Pentacalcium hydroxide tris(orthophosphate) (CAS 12167 -74 -7)

A GPMT study according to OECD 406 was performed to assess the skin sensitisation potential of pentacalcium hydroxide tris(orthophosphate) in female Dunklin-Hartley guinea pigs following an intradermal induction with 0.5% of the test substance and an occlusive epicutaneous induction with 100% and an occlusive epicutaneous challenge with 100% test substance. These concentrations were the highest concentrations which caused mild to moderate skin irritation. 10 animals were used in the test group and 5 in the negative control group. At challenge, 0/10 positive responses were noted in the test group after 24 h or 48 h and 0/5 positive responses were noted in the control group following treatment with 100% pentacalcium hydroxide tris(orthophosphate) after 24 h or 48 h. Thus, the test material was considered to be a non-sensitiser under the conditions of the test.

 

In conclusion, since pentacalcium hydroxide tris(orthophosphate) is a reliable read across substances and did not show skin sensitising potential, magnesium hydrogenorthophosphate is considered to be also not sensitising.

Further in vivo testing is deemed to be scientifically unjustified.

 

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Classification is not proposed on the basis of read-across from an analogue substance (pentacalcium hydroxide tris(orthophosphate). Further in vivo testing is deemed to be scientifically unjustified.