Ethylbenzene

Endpoint summary

Description of key information

Acute toxicity data by oral, inhalation and dermal route indicate ethylbenzene is harmful by inhalation

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

3 500 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

17 629 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

15 400 mg/kg bw

Additional information

Human data on the acute toxicity of ethylbenzene are not available and studies have been limited to assessments of odor and irritation/sensory irritation. In animals ethylbenzene proved to be harmful by inhalation of the vapours (the inhalation LC50 for rats is 4000 ppm or 17.6 mg/l/4 hours) (Union Carbide, 1949). Oral and dermal toxicity is low with LD50 values above 2000 mg/kg: an oral LD50 of 3500 mg/kg was determined for rats in general (Wolf et al., 1956), and an oral LD50 of 5460 mg/kg specifically for male rats (Smyth et al., 1962); the acute dermal toxicity was tested with rabbits and revealed a dermal LD50 of 15.4 g/kg (Union Carbide, 1949). On the basis of the inhalation toxicity results ethylbenzene has to be classified as "Xn, harmful" and labelled with "R 20, harmful by inhalation". Labelling because of the acute oral and dermal toxicity is not warranted.

Gerarde (1960) hypothesized that pulmonary injury resulting in chemical pneumonitis might be the principal cause of the deaths observed after oral administration of ethylbenzene to rats because necropsy after oral administration revealed hyperaemia and haemorrhage of the lungs. As a result of his experiments he concluded that aspiration of even a small amount of ethylbenzene may cause severe lung injury. And due to its low viscosity and surface tension ethylbenzene would spread over a large area of pulmonary tissue, causing oedema and haemorrhage. Therefore, labelling with "R 65, Harmful: May cause lung damage if swallowed" is necessary.

Justification for classification or non-classification

Acute toxicity data are available for the oral, dermal and inhalation routes.

 

Oral LD50 for rats: 3500 mg/kg bw. In accordance to Directive 67/548/EEC and EU CLP (Regulation (EC) No. 1272/2008), classification is not required for acute oral toxicity based on the available data. UN GHS defines a fifth category for acute toxicity for chemicals with LD50 values between 2000 and 5000 mg/kg bw. Therefore, in non-EU countries that adopt UN GHS this substance may be allocated to Acute Toxicity Category 5.

 

Dermal LD50 for rabbits: 15.4 g/kg bw. No classification in accordance to Directive 67/548/EEC, EU CLP (Regulation (EC) No. 1272/2008) and UN GHS.

          

Inhalation LC50 for rats: 17.6 mg/l/4h (approx. 4000 ppmV). Xn harmful, R20 (harmful by inhalation) in accordance to Directive 67/548/EEC; Acute Toxicity Cat. 4, H332, harmful if inhaled in accordance to EU CLP (Regulation (EC) No. 1272/2008) and UN GHS.

 

Lung toxicity after oral exposure;There is indication from animal experiments that pulmonary injury resulting in chemical pneumonitis might be the principal cause of the deaths observed after oral administration of ethylbenzene to rats because necropsy after oral administration revealed hyperaemia and haemorrhage of the lungs. Therefore aspiration of even a small amount of ethylbenzene may cause severe lung injury. And due to its low viscosity and surface tension ethylbenzene would spread over a large area of pulmonary tissue, causing oedema and haemorrhage.

 

Therefore, the following classification is proposed:

 

R 65, Harmful: May cause lung damage if swallowed in accordance to Directive 67/548/EEC. A harmonized classification for ethylbenzene exists, however this hazard category is not included. Recommend is to add R65.

 

Aspiration Cat 1(b) based on animal and physico-chemical data; H304; may be fatal if swallowed and enters the airways in accordance to EU CLP (Regulation (EC) No. 1272/2008) and UN GHS.

After reviewing this information, the Committee for Risk Assessment concluded that ethylbenzene may be fatal if swallowed and enters the airways (RAC, 2012 a).

RAC (2012) Opinion proposing harmonised classification and labelling at EU level of ethylbenzene. ECHA/RAC/CLH-O-0000001542-81-03/F. Committee for Risk Assessment, adopted 5 June 2012.