Registration Dossier

Administrative data

Description of key information

ENB has a relatively low degree of acute toxicity in several species via oral, dermal, and inhalation routes of administration.
Oral LD50: All rat. male: 2276mg/kg, female: 5071mg/kg, sex not specified: 2.83, 3.08, 3.125ml/kg
Inhalation LC50: Rat male: 6.23, 13.5mg/l, female: 11.25, 15.1mg/l. Mouse: male 5.5 mg/l, female 3.7mg/l. Rabbit male: 15.5mg/l. Guinea pig male: 14.4mg/l
Dermal, rabbit LD50: 5.66 ,>8, 9.17ml/kg

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50
2 200 mg/kg bw

Acute toxicity: via dermal route

Endpoint conclusion
Dose descriptor:
LD50
5 000 mg/kg bw

Additional information

There are a number of acute toxicity studies on ENB by the inhalation route, the oral route and the dermal route. The data described in Ballantyne et al (1997) were selected as the key studies since the analytical purity of the ENB was specified and because they are well reported studies. The acute oral LD50value was 2276 mg/kg for male rats and 5071 mg/kg for female rats. The acute inhalation LC50values were 13.3 mg/L (2717 ppm) for male rats and 14.8 mg/L (3015 ppm) for female rats. The dermal LD50value was greater than 7168 mg/kg for male and female rabbits.

Justification for classification or non-classification

Based on the available animal data, there is sufficient information available to determine that no classification is required for the oral and dermal routes of acute exposure.

For the inhalation route, the data available indicates that classification as harmful is required. Under regulation 1272/2008, the rat (average of results from all studies and sexes), rabbit and guinea pig data would indicate classification as harmful. The data on mice indicates a classification as toxic. A classification based on the response in the majority of species and therefore a classification of harmful seems most appropriate. This is supported by the observation that the range of LC50 values span the range 13 -56% of the saturated vapour concentration at 20C.

There is no data to indicate classification is required by the oral or dermal routes.