Hydrocarbons, C10-C13, aromatics, <1% naphthalene

Neurotoxicity

Description of key information

Acute CNS effects: NOAEL for rats: 600 mg/m3 (based primarily on volatility)

Additional information

A study was conducted to evaluate the behavioral effects of rats exposed to Solvarex 10. Three test groups (with one control) comprising of 8 rats each were exposed to Solvarex 10 at different concentrations including: 0 (air), 0.2 g/m3 (35ppm), 0.6 g/m3 (110ppm), 2.0 g/m3 (365ppm). Animals were exposed to the test atmosphere 8 hours/day for 3 consecutive days. Test methods included selected functional observational measures, automated motor activity assessment and visual discrimination performance.

 

Results of the behavioral tests indicated Solvarex 10 induced disturbances in measures from different functional domains including gait abnormalities and visual discrimination performance. Some gait abnormalities were observed throughout the 3-day exposure period in rats exposed to the highest concentration of Solvarex 10 (2 g/m3). The severity of these abnormalities was low to moderate. Effects were also observed on measures of learned performance. Exposure to the highest concentration of Solvarex 10 (2 g/m3) induced increased latencies to make a correct choice and latencies to obtain water reinforcement, and also increased the variability in the speed of responding. The effects of exposure to Solvarex 10 on performance speed were most clearly observed after the first 8-hour exposure period. Also, a small but significant decrease in the number of collected reinforcements was observed in the highest exposure group (2 g/m3).

 

Short-term, high-level exposure to Solvarex 10 induced some mild, reversible neurobehavioral effects on functional observations and measurements of learned performance. Effects were observed during or after 3 consecutive 8 hour exposures at the highest tested concentration of 2.0 g/m3 of Solvarex 10. Exposure to 0.2 g/m3 or 0.6 g/m3 of Solvarex 10 did not induce exposure-related neurobehavioral effects.

Justification for classification or non-classification

No chronic neurotoxicity specific studies for C10-C15 Aromatic fluids were located. However, in a 13 week subchronic inhalation study, the toxicity of C10-C15 Aromatic fluids was examined in both rats and dogs (Carpenter, 1977). There were no neurological effects noted by the researchers in either species. There were no abnormalities noted in the histopathological examination of the brain or in the peripherial nerves for either species. The NOAEC for rats and for dogs was determined to be > 0.38 mg/L, which was the highest concentration tested. Therefore, C10-C15 Aromatic hydrocarbon fluids are not likely to cause neurotoxicity.

Carpenter CP, Geary DL Jr, Myers RC, Nachreiner DJ, Sullivan LJ, King JM. 1977. Petroleum hydrocarbon toxicity studies XIV. Animal and human response to vapors of "high aromatic solvent". Toxicol Appl Pharmacol. 1977 Aug;41(2):235-49.