Carbon black

Acute Toxicity: dermal

Administrative data

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 September 1995 to 27 September 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1995

Report date:

1995

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: OECD Guidelines

Version / remarks:

Unspecified

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: EEC Council directive

Version / remarks:

Unspecified

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: Federal Insecticide, Fungicide and Rodenticide Act (40 CFR)

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: Toxic Substances Control Act 40 CFR

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Carbon black

EC Number:

215-609-9

EC Name:

Carbon black

Cas Number:

1333-86-4

Molecular formula:

C

IUPAC Name:

carbon

Test material form:

solid: nanoform, surface-treated

Details on test material:

NANOFORM
- shape: spheroidal, spherical
- aspect ratio: n/a
- particle size distribution: D10: >=7<=11 nm; D50: >=10<=15 nm; D90:
>=15<=20 nm
- crystal structure: amorphous
- specific surface area: >=200<=300 m²/g
- surface treatment of the tested nanoform: Sulfanilic Acid (121-57-3)

Appearance: Fine black powder
Storage conditions: Room temperature

Test animals

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Rationale for alternative/additional species to rat: The rabbit is the animal model of choice. The test system is designated by U.S. federal regulations and the OECD Guidelines since it has been used historically for this type of study and allows the data to be compared to that of other compounds.
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation: not specified
- Weight: 2049-2351 g
- Fasting period before study: not specified
- Housing: housed singly in wire mesh suspension cages
- Diet: ad libitum
- Water: tap water ad libitum
- Acclimation period: at least 5 days
- Method of randomisation in assigning animals to test and control groups: The animals were randomly caged according to Standard Operating Procedure.

ENVIRONMENTAL CONDITIONS
- Temperature: 61 - 70 °F
- Humidity: 40 - 70 %
- Air changes: not specified
- Photoperiod: 12 hour light/12 hour dark cycle

IN-LIFE DATES: 12 September 1995 to 27 September 1995

Administration / exposure

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

TEST SITE
- On the day prior to dosing, the hair of each rabbit was closely clipped from the dorsal surface of the trunk, so as to expose not less than 10 % of the body surface area.
- The test material was held in contact with the skin by wrapping gauze around the trunk of each animal and securing with paper tape. The test site was further covered with a sleeve of rubber dental dam to retain the gauze dressing and test material and ensure that the animals could not ingest the test material. Each rabbit was then fitted with an Elizabethan collar to prevent the removal of the wrapping.

REMOVAL OF TEST SUBSTANCE
- At the end of an approximate 24 hour exposure period, the wrapping was removed and any unabsorbed test material remaining on the skin was removed by gentle sponging using a towel moistened with tap water. The presence or absence of residual test material on the wrapping and on the rabbits was documented.

TEST MATERIAL
- The appropriate amount of test material (2.0 g/kg of bw) was weighed, moistened with 5.0 mL of distilled water, and applied uniformly to the dorsal surface of the animal.

Duration of exposure:

24 hours

Doses:

Single dose of 2.0 g/kg

No. of animals per sex per dose:

5 animals per sex

Control animals:

no

Details on study design:

OBSERVATIONS
- Animals were observed for signs of toxicity and behavioural changes once, or more frequently if clinical signs were present on the day of test material administration.
- All surviving rabbits were maintained for 14 days following completion of the exposure period.
- All examination for gross signs of toxicity was carried out once daily with an additional check for viability during the day.
- Skin reactions and other evidence of irritation or injury including erythema, edema, atonia, desquamation, necrosis, coriaceousness, and fissuring were noted once daily.

INTERPRETATION
- The test material was categorised in accordance with Annex VII of the Fifth Adaptation Directive (EEC Commission, 1992) as indicated below:

Very toxic: < 50 mg/kg
Toxic: 50 mg/kg through 400 mg/kg
Harmful: 400 mg/kg through 2000 mg/kg

BODY WEIGHTS
- Body weights were measured for each animal on the day of dosing, on day 7 of the observation period and at the end of the 14 day observation period.

TERMINATION
- At the end of the 14 day observation period, each surviving rabbit was euthanised via a marginal ear vein injection using Socumb euthanasia solution and weighed. A gross necropsy was performed on each animal.

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

No deaths were noted during the observation period.

Clinical signs:

other: There were no clinical signs observed during the observation period.

Gross pathology:

There were no gross necropsy findings observed.

Other findings:

SKIN REACTIONS
The only signs of skin irritation noted during the observation period were moderate to marked erythema and slight to moderate oedema. There were no other irritative effects.

Applicant's summary and conclusion

Interpretation of results:

other: Not classified according to EU criteria

Conclusions:

Under the conditions of this study the acute dermal LD50 of the test material was found to be >2.0 g/kg in male and female rabbits. According to the EEC Council Directive, the test material is not classified as harmful, toxic or very toxic based on the response observed following dermal administration.

Executive summary:

The acute dermal toxicity of the test material was evaluated in accordance with the standardised guidelines OECD, EEC Council directive, Federal Insecticide, Fungicide, and Rodenticide Act (40 CFR) and The Toxic Substances Control Act (40 CFR), under GLP conditions. 

The test material was administered as received, moistened with 5.0 mL of distilled water to give male and five female rabbits at a dose level of 2.0 g/kg. Following a single dermal administration the animals were observed for 14 days. Based on the lack of mortality observed, the acute dermal OD50 value was found to be greater than 2.0 g/kg. There were no clinical signs noted during the observation period. The only irritative signs noted during the observation period were moderate to marked erythema and mild to moderate edema. The administration of the test material did not appear to have any effect on body weight. There were no gross necropsy findings noted.  

Under the conditions of this study the acute dermal LD50 of the test material was found to be > 2.0 g/kg in male and female rabbits. According to the EEC Council Directive, the test material is not classified as harmful, toxic or very toxic based on the response observed following dermal administration.