Registration Dossier

Administrative data

Description of key information

ORAL
The LD50(oral, rat) was greater than 2000 mg/kg body weight in a study performed according to OECD guideline 401 with acceptable restrictions. Hyperpnea was as well frequently observed in all exposed rats shortly after administration. The following intoxication symptoms have been observed: transient ataxia, laboured breathing and prostration in a dose-related manner at the two higher doses.
INHALATION:
The Inhalation Hazard Test was performed to determine the hazard of volatile substances in general and chlorobenzene in particular (Klimisch H.J., 1988, Arch. Toxicol. 61, 411 - 416).
Glass flask generator was used for the generation of a vapor saturated inhalation atmosphere. The exposure system used was made of two simple glass systems with tubes for the exposure of six to ten animals. 3 male and 3 female rats have been exposed to 66 mg/L (nominal concentration) and LT0 (time T after which no animals died within 14 days of post-exposure observation period) and LT50 (time of exposure after which 50% of the animals died within 14 days of the post-exposure observation period) were calculated.
LT0 was estimated to be 0.17 h. LT 50 value was calculated from IHT results. LT50=1.8 h.
The LC50 was calculated by the applicant according to the Haber´s rule: LC50= 66 mg/L * (1.8h/4h)= 29.7 mg/L.
DERMAL:
According to REACh Annex VIII column 2, a dermal study does not need to be conducted since due to the physico-chemical parameters, exposure by inhalation is likely.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50
2 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Dose descriptor:
LC50
66 mg/m³

Additional information

ORAL The standard approach for evaluation of a substance is to apply the most critical results. In the case of chlorobenzene that would be the study results of Loeser (1982), where the LD50 of male rats is calculated as 1419 mg/kg bw. However, based on the fact that all remaining data with a reliability of 2 or 4 indicate that the LD50 for chlorobenzene in rats is greater than 2000 mg/kg bw and that Loeser found the lower LD50 only in male rats, based on a weight-of-evidence the overall LD50 is considered to be greater than 2000 mg/kg bw and Kluwe (1985) was choosen as key study. In an acute oral toxicology study according to OECD guideline 401 with acceptable restrictions F344/N rats have been administered with 250, 500, 1000, 2000 or 4000 mg/kg bw of chlorobenzene in corn oil. The LD50 was greater than 2000 mg/kg body weight. Hyperpnea was frequently observed in all exposed rats shortly after administration. In addition, the following intoxication symptoms have been observed: transient ataxia, laboured breathing and prostration in a dose-related manner at the two higher doses. DERMAL: According to REACh Annex VIII column 2, a dermal study does not need to be conducted since due to the physico-chemical parameters, exposure by inhalation is likely. INHALATION: The Inhalation Hazard Test (IHT) was performed to determine the hazard of volatile substances in general and chlorobenzene in particular (Klimisch H.J., 1988, Arch. Toxicol. 61, 411 - 416). Glass flask generator was used for the generation of a vapor saturated inhalation atmosphere. The exposure system used was made of two simple glass systems with tubes for the exposure of six to ten animals. 3 male and 3 female rats have been exposed to 66 mg/L (nominal concentration) and LT0 (time T after which no animals died within 14 days of post-exposure observation period) and LT50 (time of exposure after which 50% of the animals died within 14 days of the post-exposure observation period) were calculated. LT0 was estimated to be 0.17 h. LT 50 value was calculated from IHT (Inhalation hazard Test) results. LT50=1.8 h. The LC50 was calculated by the applicant according to the Haber´s rule: LC50= 66 mg/L * (1.8h/4h)= 29.7 mg/L (29700 mg/m³). Considering the available data classification is not necessary. But according to Annex VI of the Regulation 1272/2008 EC chlorobenzene has to be classified as Category IV for inhalation toxicity.

Justification for classification or non-classification

According to Annex VI of the Regulation 1272/2008 EC chlorobenzene has to be classified as Category IV for inhalation toxicity.