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Description of key information

There are no specific neurotoxicity data on any of the streams within the High Benzene Naphtha category. Of the specific components present in some streams toluene and n-hexane are recognised as having neurotoxic activity. These effects are briefly discussed in the section on repeated dose toxicity (5.6.3).

Key value for chemical safety assessment

Additional information

Toluene exposure can produce central nervous system pathology in animals after high oral doses. In humans neuropsychological effects have been reported, particularly when exposures are not well controlled. There was no evidence that long-term exposure to toluene at 26 ppm for 21 years had any effects on cognitive function (Seeber et al, 2004).

In animals following oral or inhalation exposure n-hexane can produce neurologic dysfunction of motor or sensorimotor nerves resulting in weight loss and paralysis (Spencer and Schaumberg, 1985). Epidemiological studies on n-hexane have shown an association between inhalation exposure to n-hexane and neurological symptoms in occupationally exposed individuals. The NOAEC for peripheral neuropathy is reported to be 20 ppm (70 mg/m3) (UK HSE, 1990).


UK HSE (1990). N-Hexane occupational exposure standard. UK HSE Review 1990, D34-D35, Published 1993

Justification for classification or non-classification

See section 5.6 for overall classification for repeated dose toxicity.