boron nitride (hexagonal)

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Remarks:

GLP conform study following US regulation for the enforcement of the "Federal Hazardous Substances Act 16 CFR 1500". Reports are not as detailed as modern protocols but include all required information. The principles and methodology used for testing is comparable to modern OECD 404 guideline besides longer exposure time compared to OECD 404 which is no considered critical regarding reliability of the study. Interpretation of the results is different to OECD 404 protocols and frequency of observation is lower. This is not considered critical regarding reliability of the study as results are reported in a way that interpretation according to the OECD 406 guideline was possible and 3 of four animals did not show any response after 72h. Therefore, the study is considered to be reliable.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1990

Report date:

1990

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: US regulation for the Enforcement of the Federal Hazardous Substances Act (16 CFR 1500)

Deviations:

no

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

yes

Remarks:

longer exposure time, less frequent observations

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

boranylidyneamine

EC Number:

701-292-9

Cas Number:

10043-11-5

Molecular formula:

BN

IUPAC Name:

boranylidyneamine

Details on test material:

- Name of test material (as cited in study report): 89-006 (UHP 2020)
- Substance type: inorganic
- Physical state: solid
- Analytical purity: < 98.5 %
- Impurities (identity and concentrations): B2O3 0.1 %, carbon 0.4 %, ammonia 90 ppm, lead 20 ppm
- Stability under test conditions: stable
- Storage condition of test material: room temperature in plastic bag
- Particle size: D50 4.3 µm

Test animals

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Clerco Research Farm
- Age at study initiation: young adult
- Housing: single, suspension cages with wire mesh floors
- Diet (e.g. ad libitum): purina laboratory rabbit chow
- Water (e.g. ad libitum): ad libitum
- Acclimation period: min 1 day

ENVIRONMENTAL CONDITIONS
- Photoperiod (hrs dark / hrs light): 12 hrs. light/12 hrs. dark

Test system

Type of coverage:

occlusive

Preparation of test site:

other: shaved and intact

Vehicle:

physiological saline

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 g
VEHICLE
- Amount(s) applied (volume or weight with unit): Test material moistened with 0.5 ml physiol. saline

Duration of treatment / exposure:

24 h

Observation period:

72 h

Number of animals:

6 (3 male and 3 female)

Details on study design:

TEST SITE
- Area of exposure: 1" x 1" gauze square

SCORING SYSTEM:
Application sites are scored for each rabbit immediately after removal of test material (24 h) and after 72 hours. The scoring system used is the following:
Erythema and Eschar Formation (mostseverely affected area graded):
No erythema: 0
Very slight erythema (barely perceptible): 1
Well defined erythema: 2
Moderate to severe erythema: 3
Severe erythema (beet redness) to slight eschar formation (injuries in depth): 4
Edema Formation (most severely affected area graded):
No edema: 0
Very slight edema (barely perceptible): 1
Slight edema (edges of area well-defined by defnite raising): 2
Moderate (raised approximately 1mm): 3
Severe edema (raised more than 1 mm and extending beyond area of exposure): 4

The values for each rabbit were totaled and averaged for each of the categories:
1 Erythema and eschar formation, intact skin, 24h
2 Erythema and eschar formation, abraded skin, 24h
3 Erythema and eschar formation, intact skin, 72h
4 Erythema and eschar formation, abraded skin, 72h
5 Edema, abraded skin 24 h
6 Edema, intact skin 24 h
7 Edema, abraded skin 72 h
8 Edema, intact skin 72 h

The eight average scores are added and the results divided by four to obtain the Primary Irritation Index. A corrosive material is a material which causes destructive or irreversible damage to tissue. A primary irritant is one which gives a PII of five or more.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

erythema score

Basis:

mean

Time point:

48 h

Remarks on result:

not measured/tested

Results 2

Irritation parameter:

edema score

Basis:

mean

Time point:

48 h

Remarks on result:

not measured/tested

Results 3

Irritation parameter:

primary dermal irritation index (PDII)

Basis:

mean

Score:

1.9

Max. score:

8

Reversibility:

fully reversible within: 72 h

Remarks on result:

other: No changes in coloration or texture of the skin were noted. No evidence of corrosion was found.

Results 4

Irritation parameter:

erythema score

Basis:

mean

Time point:

24 h

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 72h

Results 5

Irritation parameter:

edema score

Basis:

mean

Time point:

24 h

Score:

1.5

Max. score:

4

Reversibility:

fully reversible within: 72h

Results 6

Irritation parameter:

erythema score

Basis:

mean

Time point:

72 h

Score:

0

Max. score:

4

Reversibility:

fully reversible

Results 7

Irritation parameter:

edema score

Basis:

mean

Time point:

72 h

Score:

0

Max. score:

4

Reversibility:

fully reversible

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Application of hexagonal boron nitride for 24 h to intact and abraded skin did not result in damage to the skin. Slight edema observed directly after 24 h exposure was not existent 48 h after end of exposure (72 h). Hexagonal boron nitride does neither have to be classified as irritant nor as corrosive.