Lanthanum oxide

Acute Toxicity: dermal

Administrative data

Endpoint:

acute toxicity: dermal

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1976

Report date:

1976

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: Guidelines of the Department of Transportation (D.O.T.), Code of Federal Regulations, Title 49, Part 173

GLP compliance:

no

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Rare Earth solution

IUPAC Name:

Rare Earth solution

Details on test material:

- Name of test material (as cited in study report): Rare Earth Solution Code #1455
- Molecular formula (if other than submission substance): LaCl3*3(H2O)
- Physical state: amber liquid
- Concentration of solution: 100%
- Analytical purity: no data

Test animals

Species:

rabbit

Strain:

New Zealand White

Sex:

not specified

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Skippack Breeding Farms
- Weight at study initiation: approx. 3 kg
- Housing: individually in stainless steel suspended cages
- Diet (Purina Rabbit Chow) and water: ad libitum
- Acclimation period: 7 days

Administration / exposure

Type of coverage:

occlusive

Vehicle:

water

Details on dermal exposure:

10 rabbits were clipped free of fur over the entire upper back area. Rabbits showing signs of dermal irritation or lesions were replaced. Five of the test sites were abraded by making a series of five parallel superficial scratches in the dermis; the remaining five were left intact.
The compound was applied at 2 g/kg bw to the shaved skin and wrapped with an impervious band which was left in place for 24 h.

Duration of exposure:

24 h

Doses:

2000 mg/kg

No. of animals per sex per dose:

10 (no data about sex)

Control animals:

no

Details on study design:

- Duration of observation period following administration: Animals were observed for mortality for up to 48 hours
- Frequency of observations: Treatment sites were evaluated for signs of erythema or edema according to the Draize Scoring System after 24 and 48 h. Body weight was recorded at dosing
- Necropsy of survivors performed: no

Results and discussion

Effect levels

Effect levels 1

Sex:

not specified

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Remarks on result:

other: Test substance: Rare Earth Solution #1455

Effect levels 2

Sex:

not specified

Dose descriptor:

LD50

Effect level:

> 1 638 mg/kg bw

Remarks on result:

other: Test substance: Lanthanum chloride, anhydrous

Effect levels 3

Sex:

not specified

Dose descriptor:

LD50

Effect level:

> 1 087 mg/kg bw

Based on:

other: lanthanum oxide

Remarks on result:

other: recalculated as lanthanum oxide

Mortality:

No deaths were noted up to 48 hours after application

Clinical signs:

other: Animals appeared normal. Intact skin: Very slight erythema (5 out of 5, score 1) and very slight edema (2 out of 5, score 1) after 24 h; no signs of erythema and edema after 48 h. Abraded skin: Very slight erythema (5 out of 5, score 1) and very slight ed

Gross pathology:

no data

Applicant's summary and conclusion

Conclusions:

The acute dermal toxicity of the more soluble rare earth chloride solution containing mainly lanthanum chloride can be used as a worst case read across for lanthanum oxide as well. As lanthanum oxide is less soluble it is expected to be less available systemically after dermal contact and is thus expected to have a lower acute dermal toxicity than lanthanum chloride. As no toxicity of the chloride solution was observed at the limit dose it can reasonably be assumed that lanthanum oxide will also be not acutely toxic by the dermal route and further animal testing for this endpoint is not considered necessary. This is also corroborated by the anticipated low dermal absorption (see IUCLID chapter 7.1.2) and the low acute oral toxicity.