Aromatic hydrocarbons, C9-12, benzene distn.

Endpoint summary

Description of key information

Skin Irritation – Hydrocarbons, C9, Aromatics are not corrosives and are mild to moderate dermal irritants for rabbit (OECD TG 404).  A series of skin irritation studies were conducted using rabbits and standard test protocols. The mean erythema scores in the four independent key studies ranged from 1.9 to 4.0; mean edema scores in these same studies ranged from 0.0 to 2.2. Therefore, Hydrocarbons, C9 aromatics can be considered to be mildly to moderately irritating to the skin, with any effects generally reversible.  In addition, a study was conducted in which 26 human volunteers were dermally exposed to C9 aromatics. Results showed no evidence of aromatics being a dermal irritant to humans. Using qualitative weight of evidence reasoning, the C9 Aromatics may cause mild skin irritation, but results are insufficient to classify. 
Ocular Irritation – C9 Aromatics are not ocular irritating for rabbits (OECD TG 405).  All study results indicate that the C9 Aromatics are not ocular irritants to rabbits. 
Respiratory Irritation - No studies were located to indicate that C9 Aromatics are respiratory irritants.  However, a constituent of the C9 Aromatics, 1,3,5-trimethylbenzene, is classified as an R37 respiratory irritant in Annex I. 

Additional information

Skin Irritation – Hydrocarbons,C9 Aromatics are not corrosives and are mild to moderate dermal irritants for rabbits (OECD TG 404). Topical application of Hydrocarbons, C9 Aromatics to the clipped backs of rabbits under semi-occlusive dressing for 4 hours elicited dermal responses in all animals.  The mean erythema scores in the four independent key studies ranged from 1.9 to 4.0; mean edema scores in these same studies ranged from 0.0 to 2.2. Therefore, Hydrocarbons, C9 aromatics can be considered to be mildly to moderately irritating to rabbit skin, with any effects generally reversible. In addition, a study was conducted in which 26 human volunteers were dermally exposed to Hydrocarbons, C9 aromatics. Results showed no evidence of aromatics being a dermal irritant to humans. Using qualitative weight of evidence reasoning, the C9 Aromatics may cause mild skin irritation to rabbits, but are not irritating to human skin.

 

Ocular Irritation –Hydrocarbons, C9 Aromatics are not ocular irritants (OECD TG 405) when evaluated in rabbits following a single 0.1 ml ocular instillation. Testing of Hydrocarbons,C9 Aromatics generally demonstrated reversible conjunctive redness, chemosis, and infrequent discharge in animals. Draize scores were generally low. All study results indicate that the Hydrocarbons,C9 Aromatics are not irritating for rabbits.

 

Respiratory Irritation - No studies were located to indicate that Hydrocarbons, C9 Aromatics are respiratory irritants. However, a constituent of the Hydrocarbons, C9 Aromatics, 1,3,5-trimethylbenzene, is classified as an R37 respiratory irritant in Annex I.

Justification for classification or non-classification

These findings do not warrant the classification of C9 Aromatics as skin, ocular, or respiratory irritants under the new Regulation (EC) 1272/2008 on classification, labeling and packaging of substances and mixtures (CLP) or under the Directive 67/518/EEC for dangerous substances and Directive 1999/45/EC for preparations.

 

SKIN IRRITATION: Erythema and edema scores (24, 48, and 72 average) in a human volunteer skin irritation study the scores are below the classification threshold requirements: 2.0, Directive 67/518/EEC for dangerous substances and Directive 1999/45/EC for preparation; 2.3, the new Regulation (EC) 1272/2008 on classification, labeling and packaging of substances and mixtures (CLP).

 

OCULAR IRRITATION: Ocular lesion scores (24, 48, and 72 average) are below the classification threshold requirements.

Directive 67/518/EEC for dangerous substances and Directive 1999/45/EC for preparation: 0, cornea opacity; 0, iris lesion; >2.5, redness of the conjunctivae; >2.0, oedema of the conjunctivae (chemosis).

Regulation (EC) 1272/2008 on classification, labeling and packaging of substances and mixtures (CLP): 0, cornea opacity; 0, iris lesion; >2.0, redness of the conjunctivae; >2.0, oedema of the conjunctivae (chemosis).

 

RESPIRATORY IRRITATION - There are no studies that warrant classification as a respiratory irritant under either the Directive 67/518/EEC for dangerous substances and Directive 1999/45/EC or under the new Regulation (EC) 1272/2008 on classification, labeling and packaging of substances and mixtures (CLP). However, a constituent of the C9 Aromatics, 1,3,5-trimethylbenzene, is classified as an R37 respiratory irritant in Annex I.