Progress and Prospects in Parkinson's Research/Causes/Toxins/n-Hexane

Background
The Chemical formula of n-Hexane is CH3CH2CH2CH2CH2CH3 and its alternative name is Hexyl Hydride.

It is used as a solvent in the extraction of oils from seeds, and in the manufacture and processing of paint, glues and petroleum products. Industrially it is used in the manufacture of shoes, tungsten carbide and press-proofing. Artists and painters of all descriptions are exposed to it and it has been found at waste sites, in the air surrounding fuel storage tanks and in some water supplies.

1995

Pezzoli et al studied a single case of n-Hexane induced PD. Their conclusions stated:-

"“Positron emission tomography studies demonstrated regional striatal abnormalities of the nigrostriatal dopaminergic system and of glucose metabolism that were different from those found in idiopathic Parkinson's disease.'"

1996

Pezzoli et al described the case of a PD patient, who had experienced a prolonged exposure to n-Hexane. Their conclusions state:-

" “The patient developed a rapid-course disease that progressed even after withdrawal from the toxic exposure. Pathological examination and immunohistochemical analysis of the brain revealed severe and widespread dopaminergic neuronal loss, associated with severe gliosis, in the substantia nigra, and almost complete loss of tyrosine hydroxylase immunostaining in the striatum. No Lewy bodies were detected. Neuronal loss was also observed in the periaqueductal gray matter, locus ceruleus, and pedunculopontine nucleus. These changes, combined with the moderate anemia due to marrow suppression, and the mild axonal neuropathy observed in vivo, are suggestive of a hydrocarbon toxic insult.”"

2003

Canesi et al record the results of a two-part experiment. Their conclusions state:-

"“In the first part, in order to assess whether age and PD may affect the catabolism of the hydrocarbon n-hexane the urinary levels of its main metabolites, 2,5-hexanedione and 2,5-dimethylpyrroles, were measured in 108 PD patients and 108 healthy controls, matched by age and sex. Metabolite urinary excretion was significantly reduced in PD patients as compared with controls and was inversely related to age in both groups. In the second part the same comparison was made between 24 non-smoking and 10 smoking patients, matched to controls, after smoking of a hydrocarbon-rich cigarette. In these subjects also n-hexane and 2,5-hexanedione blood levels were measured. There was no appreciable difference in n-hexane blood levels between patients and controls in non-smokers, whereas there was a significant increase in patients over controls in smokers (p < 0.01). 2,5-hexanedione blood levels were significantly lower in patients than in healthy controls, both in non-smokers and in smokers, but the reduction was more pronounced in smokers (-46.3 % versus -10.7 %). The same was true for 2,5-hexanedione and 2,5-dimethylpyrrole urinary levels. This study suggests that aging and PD may be associated with a reduction in the capacity to eliminate the hydrocarbon n-hexane. This metabolic alteration may play a role in the pathogenesis of PD.”"

2009

Vanacore et al evaluated at length the case of a PD patient with 17 years’ exposure to n-Hexane and established a causal link.