Industrial toxicants and Parkinson's disease

Abstract

The exposure of the human population to environmental contaminants is recognized as a significant contributing factor for the development of Parkinson's disease (PD) and other forms of parkinsonism. While pesticides have repeatedly been identified as risk factors for PD, these compounds represent only a subset of environmental toxicants that we are exposed to on a regular basis. Thus, non-pesticide contaminants, such as metals, solvents, and other organohalogen compounds have also been implicated in the clinical and pathological manifestations of these movement disorders and it is these non-pesticide compounds that are the subject of this review. As toxic exposures to these classes of compounds can result in a spectrum of PD or PD-related disorders, it is imperative to appreciate shared clinico-pathological characteristics or mechanisms of action of these compounds in order to further delineate the resultant disorders as well as identify improved preventive strategies or therapeutic interventions.

Figure 1

Introduction and use of various industrial toxicants in the U.S. The commercial introduction and use of several widely used industrial contaminants are shown for the last two centuries, beginning around the Industrial Revolution. While some of these compounds, such as PCBs have had their use phased out, others such as many solvents have only had their use restricted, yet are still in high use in the U.S. In contrast, most metals are still widely used and have seen little or no restriction placed on their use. An exception to this is lead, which saw a removal from use as a gasoline additive in the 1970’s (denoted by an asterisk), resulting in a drastic reduction in the blood lead levels of the human population.