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Description of key information

In a dermal sensitization study (OECD 406) with Sodium molybdate 241/32 in water, 20 young adult female guinea-pigs of the Dunkin-Hartley strain were tested using the method of Magnusson and Kligman. No dermal reactions were seen in a period of 72 hours after challenging the test animals. Based on the available data, the source substance Sodium molybdate 241/32 is not a dermal sensitizer. 

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:
For justification of read-across please refer to the read-across report attached to IUCLID section 13.
Reason / purpose:
read-across source
Positive control results:
Sensitivity of the guinea-pig strain used is checked periodically with formalin, a known sensitiser. Formalin produced a clear positive response in all performed control experiments.
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
70 and 35 % Sodium molybdate 241/32 w/w in water
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
none
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
70 and 35 % of Sodium molybdate 241/32 w/w in water
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
none
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
other: 3rd reading
Hours after challenge:
72
Group:
test group
Dose level:
70 and 35 % Sodium molybdate 241/32 w/w in water
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
none
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
Freud's treated control
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
none
Remarks on result:
no indication of skin sensitisation
Reading:
other:
Group:
positive control
Dose level:
Formalin (Induction: Intradermal 0.1% , topical 10 % aqueous dilution)
No. with + reactions:
10
Total no. in group:
10
Remarks on result:
positive indication of skin sensitisation

Clinical signs:

No signs of ill health or toxicity were recorded.

Induction:

- Intradermal injections: Necrosis was recorded at sites receiving Freund´s Complete Adjuvant in test and control animals. A slight irritation was seen in test animals at sites receiving Sodium molybdate, 5% w/w in water for irrigation; no irritation was observed in the control animals receiving water for irrigation.

- Topical application: Slight erythema was observed in test animals following topical application with Sodium molybdate 241/32, 70% w/w in distilled water. Very slight erythema was seen in the control guinea-pigs.

Interpretation of results:
GHS criteria not met
Conclusions:
In conclusion, Sodium molybdate 241/32 is considered as not skin sensitising.
Executive summary:

In a dermal sensitization study (OECD 406) with Sodium molybdate in water, 20 young adult female guinea-pigs of the Dunkin-Hartley strain were tested using the method of Magnusson and Kligman. No dermal reactions were seen in a period of 72 hours after challenging the test animals. In this study, Sodium molybdate is not a dermal sensitizer.

This information is used in a read-across approach in the assessment of the target substance.

For justification of read-across please refer to the attached read-across report (see IUCLID section 13).

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

No data is available for Molybdenum disilicide (target substance). Thus, available data from Sodium molybdate was used in a read-across approach. Due to a lower water solubility of Molybdenum disilicide compared to Sodium molybdate the resulting bioavailability (toxicity potential) would also be expected to be lower. Therefore, the read across to the source substance Sodium molybdate is adequately protective. Details on the read-across rational are provided in section 13.

Sodium molybdate was tested negative in a dermal sensitization study according to OECD 406. Based on the results from the read-across partner Sodium molybdate, Molybdenum disilicide can be considered as not sensitizing to the skin.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

In a dermal sensitization study according to OECD 406, female guinea pigs were tested negative for Sodium molybdate. Based on the results from the read-across partner, no classification of Molybdenum disilicide is warranted.