Lanthanum trinitrate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

30 October 2012-28 November 2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well documented GLP study performed according to OECD Guideline 429 and EU Method B42. The study has been scored Klimisch 2 to reflect the ambiguity of the results (expert judgment).

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Lanthanum trinitrate

EC Number:

233-238-0

EC Name:

Lanthanum trinitrate

Cas Number:

10099-59-9

Molecular formula:

H3LaN3O9+3

IUPAC Name:

lanthanum trinitrate

Test material form:

solid: crystalline

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/CaOlaHsd

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories
- Age at study initiation: 8-12 weeks
- Weight at study initiation: 15-23 g
- Housing: Individually housed in suspended solid-floor polypropylene cages with softwood flakes
- Diet (e.g. ad libitum): ad libitum 2014C Teklad Global Rodent diet
- Water (e.g. ad libitum): ad libitum tap water
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-25 degrees C
- Humidity (%): 30-70%
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (LLNA)

Vehicle:

dimethylformamide

Concentration:

Range-finding test:
10%, 25%, 50%

Main test:
2.5, 5, 10%

No. of animals per dose:

Range-finding test: 1

Main test: 4

Details on study design:

RANGE FINDING TESTS:
- Compound solubility: soluble in vehicle
- Irritation: excessive ear thickness > 25%
- Lymph node proliferation response: Ratio of 3HTdR incorportation relative to control.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Criteria used to consider a positive response: Threefold or greater increase in 3HTdR incorporation relative to control.

TREATMENT PREPARATION AND ADMINISTRATION:
- 25 µL test item to dorsal ear surface days 1, 2, and 3
- Day 6; injection via tail vein of 250 µL PBS containing 3H-methyl thymidine (80 µCi/mL, specific activity 2.0 Ci/mmol), total 20µCi per mouse.
- Asphyxiation by carbon dioxide 5 hours after 3HTdR injection.
- Auricular lymph nodes excised, drained and pooled for each group, and 1 mL PBS added to pool.
- Cells disaggregated through 200 mesh stainless gauze, rinsed w/4mL of PBS into a petri dish.
- Suspension was transferred to a centrifuge tube w/rinse, pelleted and re-suspended twice in PBS.
- Pellet resuspended in 3 mL 5% TCA.
- After 18 hours at 4°C; precipitates recovered by centrifugation and re-suspended in 1 mL TCA and transferred to scintillation vial.
- Disintegrations per minute counted with Beckman LS6500 system

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Results and discussion

Positive control results:

Disintegrations per minute: 72230.33 dpm
Stimulation Index: 11.57

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: Vehicle-na Test item: 2.5%-2.23 5%-3.15 10%-3.26

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: Vehicle-6242.04 dpm Test item: 2.5%-13890.88 dpm 5%-19675.01 dpm 10%- 20356.72 dpm

Any other information on results incl. tables

Range finding test: excessive ear thickness (>25%) at 50% and 25% w/w in vehicle up to day 6 after exposure (~42 % ear thickness increase at both 50 and 25 %).

Main study - Observations

- Clinical Observations: there were no deaths. No signs of systemic toxicity were noted in the test or control animals during the test.

- Body weights: bodyweight changes of test animals were comparable to corresponding control (vehicle) animals.

- Ear thickness: there was no increase in ear thickness (>25%) in any of the test or control animals on days 3 and 6.

Main study

- Calculation of EC3 value: 4.59%

Applicant's summary and conclusion

Interpretation of results:

ambiguous

Remarks:

Migrated information Criteria used for interpretation of results: expert judgment

Conclusions:

At concentrations of 5% and 10% w/w in dimethyl formamide the stimulation indices are only slightly higher than the threefold increase in 3HTdR incorporation compared to the control values (3.15 and 3.26 respectively). It was also observed that the preliminary screening animals showed excessive or elevated increases in ear thickness changes, indicating irritation potential. On this basis the test item can not be clearly classified as a sensitiser.