Cobalt molybdate

Endpoint summary

Description of key information

Skin irritation: 
Human Skin Model Test, OECD 439 (in-vitro): not irritating 
Eye irritation: 
BCOP test, OECD 437 (in-vitro): not corrosive

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The skin irritation potential of cobalt molybdenum oxide was determined in the Human Skin Model Test following OECD 439 (Paulus, 2011). Three tissues of the human skin model EpiDerm^TM were each treated with approx. 25 mg of the solid test substance (wetted with 25 µL DPBS-buffer). After 60 min incubation, tissues were rinsed and further incubated. After a total incubation time of 42 h the cell viability was determined by measuring photometrically the enzymatic conversion of the vital dye MTT into a blue formazan salt. DPBS-buffer was used as negative control, 5% SDS-solution was used as positive control.

After treatment with the negative control, the absorbance values were within the required acceptability criterion of 1.0 < mean < 2.5. Variation within tissues was acceptable. After treatment with the test substance, the relative absorbance values were increased to 110.6%. This value is well above the threshold for the irritation potential (50%). Therefore, the test substance is considered not irritant in the Human Skin Model Test.

As discussed in the OECD 439, the Human Skin Model Test can be used to identify a non-classified test substance. As a consequence, the available test result indicates that neither irritation nor corrosion potential of the test substance is to be expected.

There are no in-vivo data on skin irritation available for cobalt molybdenum oxide.

 

The potential of cobalt molybdenum oxide to cause ocular corrosivity or severe irritancy was evaluated in the Bovine Corneal Opacity and Permeability (BCOP) test following OECD 437 (Paulus, 2011). Isolated corneas from the eyes of cattle were used. Each treatment group (test substance, negative/positive controls) consisted of three eyes where the cornea has been excised and mounted to a holder. Depending on the physical nature and chemical characteristics of the test substance, the open-chamber method was used. Toxic effects to the cornea were measured as opacity and permeability. For each treatment group an in-vitro irritancy score (IVIS) was calculated. A substance that induces an IVIS superior or equal to 55.1 is defined as a corrosive or severe irritant. The result of the test was negative (IVIS= -0.369), indicating the cobalt molybdenum oxide is not corrosive. The positive control was valid.

Negative in-vitro corrosivity responses in the BCOP test are not conclusive with respect to non-classification or classification as irritant. As a worst case scenario, cobalt molybdenum oxide is considered to be irritating to the eyes.

There are no in-vivo data on eye irritation available for cobalt molybdenum oxide.

Effects on eye irritation: irritating

Justification for classification or non-classification

The available data on skin irritation of the test substance do not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.

The available data on eye irritation of the test substance meet the criteria for classification as Category 2 (H319) according to Regulation (EC) 1272/2008 and as Xi, R36 according to Directive 67/548/EEC.