Charcoal

Endpoint summary

Description of key information

The acute inhalative toxicity of charcoal (Probe 2: C-Fix=80.5%) was investigated in a study in rats that was performed according to OECD guideline no. 403, EU method B.2 and the US EPA Health Effects Test guideline OPPTS 870.1300, Acute Inhalation Toxicity, as per August 1998.

Additional information

Acute toxicity: Inhalative route

In this study, a group of 10 Wistar Crl:(WI) BR rats (5 males and 5 females) was exposed to an aerosol atmosphere. The animals were exposed for 4 h using a nose-only exposure system, followed by a 14-d observation period.

The mean achieved concentration of charcoal in the exposure was 4.968 mg/L (standard deviation: 3.624 mg/L; nominal concentration: 18.2 mg/L).

The characteristics of the test atmosphere were as follows: Mean mass median aerodynamic diameter (MMAD) (mm): 3.52 µm; geometric standard deviation: 2.46; inhalable fraction (< 4 µm): 52.3%

No death occurred in the test animals.

In males, test item related clinical signs were found between the third hour of inhalation exposure and first hour of observation period. All animals were symptom–free on first day of observation period.

In females animals, test item related clinical signs were found between the third hour of inhalation exposure and first hour of observation period. All female animals were symptom–free from first day of observation period.

The clinical signs represented the decreased activity and general reaction and dyspnoea.

In both genders, body weight loss was observable on the day of inhalation exposure. In both sexes, a compensation of body weight loss was found from third day of observation period.

On basis of body weight and body weight gain data, there was no notable test item effect observable in the exposed animals.

In conclusion, a single 4-h nose-only exposure to charcoal sample Probe 2 to CRL: (WI) BR rats followed by a 14-day observation period at a dose level 5 mg/L was not associated with mortality or any test item-related toxicological findings on the male and female animals.

Accordingly, the acute inhalation median lethal concentration (4-h LC₅₀) of charcoal rats was therefore considered to be greater than 4.97 mg/L.

 

Acute toxicity: Oral route

According to REACh Regulation (EC) No. 1907/2006, Annex IX, 7.1.5. column 2, studying the acute toxicity after oral administration is not required as acute toxicity upon inhalation has been investigated.

 

Acute toxicity: Dermal route

Testing is not required as inhalative data are available (see above). In addition, due to the physicochemical properties (log P_OW<3) and its amorphous structure, dermal absorption of charcoal has not to be expected. Moreover, according to GC-MS results from charcoal as such and an organic extract of charcoal only traces of some volatile organic compounds were detectable at room temperature (see IUCLID section 8 for details).

 

 

 

 

Justification for classification or non-classification

Based on the results of the acute inhalative toxicity study in rats, charcoal is not classified for acute inhalation toxicity as specified in the current EU-CLP regulation.

 

A classification of charcoal for acute oral and acute dermal toxicity is not possible, as no studies with charcoal were conducted for these endpoints. However, it is reasonable to assume that charcoal is virtually non-toxic when applied to the skin or ingested orally, since it is well known that charcoal is not systemically absorbed through the skin or after oral ingestion and also does not induce any overt local effects in the skin and mucous membranes.