Cerium

Endpoint summary

Description of key information

Repeated dose toxicity oral - NOAEL (subacute, rat): 150 mg/kg bw/day
Repeated dose toxicity inhalation - NOAEC (subchronic, rat): 5 mg/m3

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Dose descriptor:

NOAEL

150 mg/kg bw/day

Study duration:

subacute

Species:

rat

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Dose descriptor:

NOAEC

5 mg/m³

Study duration:

subchronic

Species:

rat

Additional information

Repeated oral toxicity:

Test Regulation, B.7 “Repeated dose toxicity, oral” reads that the test substance is administered by gavage or via the diet or drinking water.Cerium metal presents sample preparation constraints due to the fact that cerium metal powder quickly oxidises under normal atmosphere. Therefore, studies to characterise the acute toxicity oral behaviour of cerium metal have been done on cerium-compounds with 3+ valency (i.e. cerium chloride, cerium carbonate), based on the read-across approach as explained in the CSR.

Repeated inhalation toxicity:

Only dusty forms of a substance (never massive) could be of relevance for the inhalation exposure. Dusty forms of Ce however cannot be found under the normal atmosphere (see flammability properties), but only its oxidised form CeO2. According to published data (see literature above) CeO2 would be the form of cerium typically encountered in industrial exposures. Exposure to general population to CeO2 coming from the foreseen use of cerium metal as such or in an alloy, can be disregarded as irrelevant.

Therefore, read-across to CeO2 acute and chronic inhalation exposure (IUCLID5 endpoints 7.2.1 and 7.5.3) will be applied.

Repeated dermal toxicity:

The foreseen test to study the acute dermal toxicity is not suitable for this sample, since it is not feasible to have cerium powder under normal atmosphere due to its flammable behaviour (similarly as already explained in the endpoint 7.2 Acute Toxicity).

 

The oral and inhalation routes of exposure are more relevant as they have been already described in the Toxicological Review “Cerium oxide and Cerium compounds” – EPA/IRIS Sept 2009. Therefore, dermal acute toxicity information can be waived.

Repeated dose toxicity: via oral route - systemic effects (target organ) digestive: stomach

Repeated dose toxicity: inhalation - systemic effects (target organ) other: all gross lesions and masses

Justification for classification or non-classification

On the view of the threshold values and under consideration of the classification criteria, no repeated dose toxicity classification of cerium metal is justified.