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Administrative data

Description of key information

Lanthanum oxide was of low acute  toxicity to rats via the oral and inhalation routes of exposure. No mortality and signs of toxicity were observed at the limit doses of 5000 and 10000 mg/kg bw via the oral route and 5.3 mg/L via the inhalation route of exposure. The analoguous substance lanthanum chloride was also tested via the dermal exposure route in rabbits and did not reveal any signs of toxicity at the limit dose of 2000 mg/kg bw.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
discriminating dose
10 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Dose descriptor:
discriminating conc.
5 300 mg/m³

Acute toxicity: via dermal route

Endpoint conclusion
Dose descriptor:
discriminating dose
2 000 mg/kg bw

Additional information

No mortality and signs of toxicity were reported in several literature references investigating the acute oral toxicity of lanthanum oxide up to dose levels of 10000 mg/kg bw in rats. A recent inhalation study with lanthanum oxide (4 h exposure to dust aerosols of a MMAF of 3.5 micro-m) according to modern guidelines and GLP did not reveal any mortality or test substance related signs of toxicity at a limit concentration of 5.3 mg/L. Similar results were obtained for the closeley related substance lanthanum carbonate. No acute dermal toxicity study is available for lanthanum oxide itsself, but an acute dermal toxicity study in rabbits with lanthanum chloride did not reveal any adverse effects at the limit dose of 2000 mg/kg bw of the test substance. As the dermal absorption of lanthanum oxide is considered very limited and lower than that of lanthanum chloride, no acute dermal toxicity is to be expected from dermal lanthanum oxide exposure. This conclusion is also supported by the low toxicity via the oral and inhalation routes of exposure.

Justification for classification or non-classification

Due to the low acute oral toxicity in rats: LD50, oral, rat > 10000 mg/kg bw, the low inhalation toxicity LC50, inhalation (4 h), rat > 5.3 mg/L and the low dermal toxicity of the structurally related lanthanum chloride LD50, dermal, rabbit > 2000 mg/kg bw, no classification for acute toxicity is warranted.