Cerium trinitrate

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

From October 29 to November 1 1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Well documented study according to Guideline FHSA, 16 CFR 1500.4. The study can be considered similar to OECD Guideline 404 but represents a worst-case approach as the animals were exposed for 24 hours (instead of 4 hours) using an occlusive dressing (instead of semi-occlusive), and next to intact skin also abraded skin was exposed.

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1990

Report date:

1990

Reference 2

Reference Type:

publication

Title:

Unnamed

Year:

1993

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: FHSA, 16 CFR 1500.41

Deviations:

not specified

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

yes

Remarks:

- no scoring at 1 and 48 hours; 24 hours of exposure instead of 4 hours; occlusive wrap instead of semi-occlusive; also abraded skin exposed; no 14d observation period

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Cerium nitrate, hexahydrate

IUPAC Name:

Cerium nitrate, hexahydrate

Test material form:

solid: crystalline

Details on test material:

see 'confidential details'

Specific details on test material used for the study:

- Other: The test material was used as received, undiluted

Test animals

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Davidson's Mill Farm, S. Brunswick, NJ
- Age at study initiation: no data
- Weight at study initiation: no data
- Housing: Individually in suspended stainless steel caging with mesh floors
- Diet (e.g. ad libitum): Pelleted Purina Rabbit Chow ad-libitum
- Water (e.g. ad libitum): Tap water supplied by automatic water system
- Acclimation period: 11 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.6 - 22.2 °C
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): no data

Test system

Type of coverage:

occlusive

Preparation of test site:

other: shaved intact and abraded

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent no treatment

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 g/test site

Duration of treatment / exposure:

24 hours of exposure

Observation period:

Skin sites were evaluated at approximately 24 and 72 hours after initial exposure and scored according to 16 CFR 1500.41.

Number of animals:

6 animals in total (3 males and 3 females)

Details on study design:

TEST SITE
- Area of exposure: two application sites (dorsal and ventral surfaces from scapular to pelvic area) of 2.5 cm2 were delineated
- % coverage: 10% of body surface
- Type of wrap if used: 2 x 2-1/4 inch adhesive-backed gauze patch. The patches and entire trunk of each rabbit were then wrapped with an elastic cloth to aid in maintaining test-patch position and to minimize evaporation. Neck collars were placed on each rabbit and the rabbits were returned to their individual cages.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): The neck collars and patches were removed after 24 hours of exposure at which time the test sites were gently wiped clean of any residual test material.

SCORING SYSTEM: Skin sites were evaluated at approximately 24 and 72 hours after initial exposure and scored according to 16 CFR 1500.41.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

primary dermal irritation index (PDII)

Basis:

mean

Time point:

other: 24 and 72 hours

Score:

2

Max. score:

8

Reversibility:

not fully reversible within: 72 hours

Results 2

Irritation parameter:

erythema score

Basis:

mean

Remarks:

of 6 animals

Time point:

other: 24 and 72 hours

Score:

1

Max. score:

4

Reversibility:

not fully reversible within: 72h

Remarks on result:

other: Scores taken from intact skin only

Results 3

Irritation parameter:

edema score

Basis:

mean

Remarks:

of 6 animals

Time point:

other: 24 and 72 hours

Score:

0.67

Max. score:

4

Reversibility:

not fully reversible within: 72h

Remarks on result:

other: Scores taken from intact skin only

Irritant / corrosive response data:

At 24 hours post dose, slight erythema and edema was noted at most sites. By 72 hours, irritation had cleared from both the abraded and intact sites of two rabbits and had decreased in severity at most other test sites.

Other effects:

From days 1-3, one animal had soft feces, ano-genital staining and appeared thin and pale in color. Another animal had ano-genital staining on day 1 only. All other animals appeared active and healthy. There were no signs of gross toxicity, adverse pharmacologica effects or abnormal behaviour.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Based on the scoring system used, cerium trinitrate is classified as a mild primary skin irritant when applied as received undiluted. Based on the criteria of the CLP Regulation, cerium trinitrate should not be classified as skin irritant. Although the animals were not observed for 14 days, a decrease in irritant response was observed from 24h to 72h. It can be reasonably assumed that after 14 days, the irritant scores would be zero.