Dicerium tricarbonate

Endpoint summary

Description of key information

Oral: In the only available (and reliable study), the LD50 was determined to be > 5000 mg/kg bw.
Dermal: In the only available (and reliable study), the LD50 was determined to be > 2000 mg/kg bw.
Therefore, the test substance has practically no acute toxicity.
Inhalation:
According to the annex VIII paragraph 8.5. coulmn 2, this test can be waived.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

5 000 mg/kg bw

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Additional information

According to the annex VIII, paragraph 8.5., column 2 of the regulation : "In addition to the oral route (8.5.1), for substances other than gases, the information mentioned under 8.5.2 to 8.5.3 shall be provided for at least one other route. The choice for the second route will depend on the nature of the substance and the likely route of human exposure. If there is only one route of exposure, information for only that route need be provided.". As a long-term inhalation study on the cerium oxide propeties, showed no toxic effect, by analogous, the dicerium tricarbonate won't show any long-term toxicity by inhalation. The acute toxicity by inhalation is, by consequence, not releavant.

A long-term inhalation study (90 days) on cerium oxide, realised according to the GLP references, showing no toxic effect; by analogous, according to the strong similaries between dicerium tricarbonate and cerium oxide, the dicerium tricarbonate won't show any long-term toxicity by inhalation. According to this long-term result and by consequence, the inhalation acute toxicity test is not releavant

In an acute oral toxicity study (Lambert CE et al, 1993), groups of fasted, Sprague-Dawley rats (5/sex) were given a single oral dose of cerium carbonate (purity unknown) in distilled water at dose of 5000 mg/kg bw and observed for 14 days. As no detah occured during the study, the oral LD50 was determines for both sexes as > 5000 mg/kg bw.

The acute dermal toxicity of the test item Cerium carbonate was evaluated in rats according to OECD (No. 402, 24th February 1987) and EC (92/69/EEC, B.3, 31st July 1992) guidelines under GLP. The test item was applied to the skin of one group of ten Sprague-Dawley rats (five males and five females). The application was performed with the test item in its original form at the dose-level of 2000 mg/kg. Taking into account this purity (76.7%), a correction factor of 1.304 was used. The test site was then covered by a semi-occlusive dressing for 24 hours. Clinical signs, mortality and body weight gain were checked for a period of 14 days following the single application of the test item. All animals were subjected to necropsy. No deaths, no clinical signs and no cutaneous reactions at the treatment site were observed during the study. A slightly lower body weight gain was observed in some animals. No apparent abnormalities were observed at necropsy in any animal. Under the experimental conditions of this study, the dermal LD50 of the test item Cerium carbonate was higher than 2000 mg/kg in rats.

Justification for classification or non-classification

As the test substance did not induce any mortality at doses > 2000 mg/kg bw, it does not need to be classified according to the classification criteria of Annex VI Directive 67/548/EEC or UN/EU GHS classification system with regard to acute toxicity.