Registration Dossier

Administrative data

Description of key information

Benzene does not pose an acute hazard following ingestion (oral LD50 > 2000 mg/kg), skin contact (dermal LD50 > 5000 mg/kg) or acute inhalation (4 hour LC50 >

20 mg/L) exposures.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LD50
Value:
2 000 mg/kg bw
Quality of whole database:
Studies in rats demonstrate that the oral LD50 for benzene exceeds 2000 mg/kg bw.

Acute toxicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LC50
Value:
43 767 mg/m³
Quality of whole database:
Studies in rats demonstrate that the inhalation LC50 of benzene exceeds 20 mg/L.

Acute toxicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LD50
Value:
8 260 mg/kg bw
Quality of whole database:
Studies in rats demonstrate that the dermal LD50 for benzene exceeds 5000 mg/kg bw.

Additional information

Non-human information

Acute toxicity oral

An oral LD50 value in rats of > 2000 mg/kg is derived from two studies (Kimura et al, 1971; Withey and Hall, 1975). Although little information on clinical signs is included in these publications the EU RAR (2008) stated "depending on the dose the main clinical signs are sedation and hind-limb paralysis".

Acute toxicity inhalation

Acute inhalation toxicity of benzene is low with a LC50 value of 44.5 mg/L after a 4-hour exposure for rats. Death was reported to be caused by depression of the central nervous system. The main pathological findings were congestion of the lungs and liver (Drew and Fouts 1974).

Acute toxicity dermal

A dermal LD50 value of >8260 mg/kg bw for rabbits and guinea pigs was reported by Roudabush et al. (1965). No information on clinical signs or necropsy information are provided.

Acute toxicity: other route

No information available

Human information

The EU RAR (2008) reports "existing data on human accidents demonstrate that ingestion of 15 mL (176 mg/kg bw) benzene can secondarily cause death after collapse, bronchitis and pneumonia due to lung aspiration." "Exposure for 5-10 minutes to benzene vapours of 65-61 mg/L is fatal and exposure to 25 mg/L for 30 minutes is dangerous to life, while a one-hour exposure to 1.6 mg/L causes only some symptoms of illness (Gerarde, 1960)".


Justification for selection of acute toxicity – oral endpoint
A consistent oral LD50 value in rats of > 2000 mg/kg is available from two studies. The EU RAR concluded "depending on the dose the main clinical signs are sedation and hind-limb paralysis".

Justification for selection of acute toxicity – inhalation endpoint
The acute inhalation toxicity of benzene is low with a LC50 of > 20 mg/L in rats following a 4-hour exposure. Death was reported to be caused by CNS depression.

Justification for selection of acute toxicity – dermal endpoint
The acute dermal LD50 of benzene in rats is >5000 mg/kg bw.

Justification for classification or non-classification

Benzene is of low acute toxicity by the oral, inhalation and dermal routes with LD50/LC50 values exceeding the doses which would warrant classification under Dir 67/548/EEC or Regulation (EC) No 1272/2008 of the European Parliament.

The viscosity of benzene is low (dynamic 0.604 mPa s at 25°C) and is expected to have a surface tension of 33mN/m at 25°C) which justifies classification as harmful and should be labelled Xn, R65, "May cause lung damage if swallowed" under Dir 67/548/EEC and under Regulation (EC) 1272/2008 "Aspiration toxicity Category 1, H304".