Toluene: Toxicology and metabolism
Main article: Toluene (toxicology)

Inhalation of toluene fumes can be intoxicating, but in larger doses nausea-inducing. Chronic or frequent inhalation of toluene over long time periods leads to irreversible brain damage. The toxicity of toluene can be explained mostly by its metabolism. As toluene has very low water solubility, it cannot exit the body via the normal routes (urine, feces, or sweat). It must be metabolized in order to be excreted. in the metabolism of toluene, 95% is oxidized to become benzyl alcohol. The toxic metabolites are created by the remaining 5% that are ring oxidized to epoxides. Most of the epoxides become glutathione conjugated. However, the remainder will severely damage cells.

Behavioural Effects of Long Term Exposure
Serious adverse behavioural effects are often associated with toluene abuse related to the deliberate inhalation of solvents. Long term toluene exposure is often associated with effects such as: psychoorganic syndrome; visual evoked potential (VEP) abnormality; toxic polyneuropathy, cerebellar, cognitive, and pyramidal dysfunctions; optic atrophy; and brain lesions.

Toluene causes postural tremors by increasing extracellular concentrations of ?-aminobutyric acid (GABA) within the cerebellar cortex. Treatment with GABA agonists such as, benzodiazepines provide some relief from toluene induced tremor and ataxia. An alternative to drug treatment is vim thalamotomy. The tremors associated with toluene misuse do not seem to be a transient symptom, but an irreversible and progressive symptom which continues after solvent abuse has been discontinued.

There is some evidence that low level toluene exposure may cause disruption in the differentiation of astrocyte precursor cells. This does not appear to be a major hazard to adults; however, exposure of pregnant women to toluene during critical stages of fetal development could cause serious disruption to neuronal development.

Heptane: Symptoms Dizziness, stupor, incoordination; loss of appetite, nausea; dermatitis; chemical pneumonitis (aspiration liquid); unconsciousness.

Target Organs: Skin, respiratory system, central nervous system.