Charcoal, coconut shell

Endpoint summary

Description of key information

The acute inhalative toxicity of the Read-Across substance 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.
The acute oral toxicity of coconut shell charcoal was investigated in a study in rats that was performed according to OECD guideline no. 423.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Additional information

Acute toxicity: Inhalative route

This test was not conducted with coconut shell charcoal but due to the Read-Across approach the test results for “Charcoal” can be used:

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 rat 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, a study on the acute toxicity after oral administration is not required as acute toxicity upon inhalation has been investigated.As the study on acute toxicity upon inhalation was only performed with the Read-Across substance charcoal the testing of the acute toxicity after oral administration was performed.

In this study two groups, each consisting of three female RccHan:WIST (SPF) rats, were treated with coconut shell charcoal by single oral gavage administration at a dosage of 2000 mg/kg body weight. The test item was formulated in PEG 300 at a concentration of 0.2 g/ml and administered at a dosing volume of 10 ml/kg.

The animals were examined daily during the acclimatization period and mortality, viability and clinical sign were recorded. All animals were examined for clinical signs before treatment, within the first 30 minutes and approximately 1, 2, 3 and 5 hours after treatment on day 1 and once daily during test days 2-15. Mortality/viability was recorded before treatment, within the first 30 minutes and approximately 1, 2, 3 and 5 hours after administration on test day 1 (with the clinical signs) and twice daily during days 2-15. Body weights were recorded on day 1 (prior to administration) and on days 8 and 15. All animals were necropsied and examined macroscopically.

No intercurrent deaths occurred during the course of the study.

All animals excreted feces stained in black one day after the administration (test day 2). No other clinical signs were observed during the course of the study.

One animal showed a slight loss of body weight (-1,7%) from test day 8 to day 15. Otherwise, the body weight of the animals was within the range commonly recorded for this strain and age.

No macroscopic findings were recorded at necropsy.

The median lethal dose of coconut shell charcoal after single oral administration to female rats, observed over a period of 14 days, is:

LD₅₀(female rat): >2000 mg/kg body weight.
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 coconut shell charcoal has not to be expected. Moreover, according to GC-MS results from the Read-Across substance charcoal as such and an organic extract of charcoal only traces of some volatile organic compounds were detectable at room temperature (see section 8 of the IUCLID section 1.4 analytical information: GC-MS screening of charcoal extracts).

Justification for classification or non-classification

Based on the results of the acute inhalative toxicity studies in rats (for the Read-Across substance carcoal), coconut shell charcoal is not classified for acute inhalation toxicity as specified in the current EU-CLP regulation.

Based upon the referred classification criteria (Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008), coconut shell charcoal is not classified with respect due acute oral toxicity in the rat.

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