Naphtha (petroleum), steam-cracked middle arom.

Endpoint summary

Description of key information

Toluene is irritating to skin and eyes in animals however classification is required only with respect to skin.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

The irritation potential of toluene was reviewed and reported in the EU RAR (2003). No additional relevant animal data has been sourced in the updated literature review.

Skin

Non-human information

In the key study identified, the skin irritation potential of toluene was assessed in 7 rabbits according to EU method B4 (Exxon, 1988). Toluene caused significant inflammation of the skin as a mean erythema score exceeding 2 was observed which persisted for more than 24 hours. In addition, the inflammation persisted in all test animals at the end of the observation time (individual scores for erythema on day 7 were 2, 2, 2, 4, 2, 3, and 2). In a supporting study (Guillot et al, 1982a) skin irritation potential was assessed using four different methods. The most relevant method used a group of six rabbits and semi-occlusive dressings, although a French scoring system was used and therefore results are not readily interpreted. Toluene was classified as a slight irritant (PCI 2.13). The results are consistent with the Exxon study and indicate that toluene is irritating to skin.

Human information

No data have been found. The EU RAR (2003) stated “it is well known that toluene has a degreasing effect on the skin. After repeated exposures, toxic contact dermatitis may develop.”

Eye

Non-human information

In the key study, ocular irritation potential of toluene was evaluated in a study performed according to OECD Guideline 405, and of GLP quality (Exxon, 1995). Ocular lesions (redness, chemosis) occurred within 72 hours after exposure and persisted for at least 24 hours. However, the mean score (24, 48 and 72 hours) for redness of the conjunctivae and chemosis did not exceed values of 2.5 and 2, respectively. Sugai et al (1990) also assessed eye irritation potential. Although the report does not contain irritation scores it is reported that "corneal involvement or irritation that persists for more than 24 hours but recovers within 21 days" was seen. A third study (Guillot et al, 1982b) used a non-standard scoring system (mean ocular irritation index) that does not allow classification according to the EU system. However the conclusion that toluene was irritating to the eye with or without rinsing after 30 seconds is consistent with the results of other studies.

Human information

There are no data from direct exposure of human eyes to liquid toluene. A number of human experimental studies in volunteers have investigated reports of eye “irritation” resulting from exposures to toluene in ambient air. These studies indicate that toluene produces subjective sensations of eye irritation at concentrations ≥ 75 ppm (EU RAR, 2003). In a recent study, Muttray et al (2005) exposed twenty healthy men to a constant level of 50 ppm toluene. Acute symptoms related to eye irritation were assessed with the Swedish Performance Evaluation System (SPES) self-assessment questionnaire, once before and 3 times during exposure. Values obtained during exposure were related to pre-exposure values. There was no effect of toluene exposure on "irritation to the eye", "watering eyes" or "blurred vision”. 50 ppm (192 mg/m³) toluene is a NOAEC for eye irritation in humans.

Justification for selection of skin irritation / corrosion endpoint:
The available key and supporting studies indicate that toluene is irritating to the skin. Other information indicates that it possesses defatting properties

Justification for selection of eye irritation endpoint:
The available key and supporting studies indicate that toluene is slightly irritating to the eye but not to an extent that warrants classification

Effects on skin irritation/corrosion: irritating

Effects on eye irritation: slightly irritating

Justification for classification or non-classification

The results of animal studies show that toluene is irritating to the skin of rabbits. It is also reported that toluene has defatting properties. It is proposed that the appropriate classification is Category 2, H315, under GHS / CLP.

Toluene is slightly irritating to the eyes in both animal and human studies, but not to an extent that warrants classification.

Toluene can cause irritation to the respiratory tract in animals at very high concentrations. The irritant effect of lower concentrations has not been examined and no classification for respiratory irritation is proposed.