Carbon black

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

January to June 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

yes

Limit test:

no

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, no surface treatment

Test animals

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

The test animals were mated female Wistar rats. The age at start of test was 13 to 14 weeks.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

CMC (carboxymethyl cellulose)

Remarks:

0.5%

Details on mating procedure:

Pregnant females were used.

Duration of treatment / exposure:

Pregnant female rats were dosed through daily oral gavage at 0, 100, 300 or 1 000 mg/kg/day (24/group) during the sensitive period of organogenesis [day 5 through day 19 of gestation].

Frequency of treatment:

Daily through days 5 to 19 of gestation.

Duration of test:

Following dosing on gestation days 5 through 19, the dams were killed on gestation day 20 and subjected to macroscopic examination. Usual litter parameters were recorded and foetuses were sexed, weighed and submitted to external examination. About one half of the foetuses were also examined for soft tissue anomalies, and remaining foetuses were examined for skeletal anomalies.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

100 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

300 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

1 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

24 animals per dose

Control animals:

yes, concurrent vehicle

Results and discussion

Results: maternal animals

Effect levels (maternal animals)

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Remarks on result:

other: discoloration of faeces was not considered an adverse effect

Maternal abnormalities

Key result

Abnormalities:

no effects observed

Results (fetuses)

Effect levels (fetuses)

Key result

Dose descriptor:

NOEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no adverse effects reported

Fetal abnormalities

Key result

Abnormalities:

no effects observed

Overall developmental toxicity

Key result

Developmental effects observed:

no

Applicant's summary and conclusion

Conclusions:

The oral No Observed Adverse Effect Level (NOAEL) for maternal toxicity and the No Observed Effect Level (NOEL) for developmental toxicity were both set at 1000 mg/kg bw/day in a study evaluated by the SCCS

Executive summary:

The SCCS summarized the study and reports that the study authors concluded that oral administration of carbon black to pregnant rats at 100, 300 or 1 000 mg/kg bw/d during the sensitive period of organogenesis was well tolerated. There were no adverse maternal changes or any effects on embryo-fetal development. Accordingly, under the conditions of this study, the No Observed Adverse Effect Level (NOAEL) for maternal toxicity and the No Observed Effect Level (NOEL) for developmental toxicity were both set at 1000 mg/kg bw/day.

This study is used in a weight of evidence assessment for the developmental toxicity assessment. Together with modelled data on deposition fractions in the lungs of rats and humans it becomes evident that a significant amount of carbon black particles inhaled by rats and humans will be cleared from the lungs into the gastrointestinal tract; making this route of exposure of relevance for the human risk assessment.