Relationship of organochlorine pesticides to Parkinsonism

Anecdotal reports and several epidemiological studies have pointed to pesti cide exposure as a risk factor for Parkinsons Disease (PD). We have reviewe d the evidence in the literature and from our laboratory which suggests tha t organochlorine compounds are the most likely class of pesticide capable o f inducing parkinsonism. Chlorinated hydrocarbons are highly lipophilic com pounds retained in adipose tissue for life. Several organochlorines, dieldr in and polychlorinated biphenyl compounds (PCBs), were found in human brain in significantly higher concentrations in caduate nucleus from post-mortem Parkinsons Disease (PD) brains compared to age-matched controls. Dieldrin has toxic effects for dopaminergic neurons both in vitro and in vivo. Dield rin inhibits mitochdondrial electron transport in a way similar to the know n dopaminergic neurotoxin methyl-phenyl-pyridinium (MPP+) resulting in bioe nergetic deficits and increased oxidative stress. We speculate that chronic exposure to low concentrations of dieldrin can lead to the demise of dopam inergic;neurons and development of a clinical syndrome of parkinsonism.