Over the past few decades, increasing concern has emerged regarding the potential role of pesticides in the development of neurological disorders like dementia with Lewy bodies and Parkinson’s disease (PD). Pesticides, notably organochlorine compounds like DDT and chlordane, have a lengthy history of use, particularly in agricultural settings.
Studies have shown that organochlorine pesticides can stimulate alpha-synuclein fibril formation, disrupt dopamine transport, and damage dopaminergic neurons, all of which are implicated in neurodegenerative diseases’ pathogenesis. Despite regulatory actions curbing their use, such as in Japan since the 1960s, the long-lasting consequences of exposure to these pesticides are evident, with a latency period between exposure and the diagnosis of dementia with Lewy bodies.
The ingestion of pesticides is believed to initiate peripheral Lewy pathology through various mechanisms, including transneuronal and retrograde axonal transport of alpha-synuclein. Experimental evidence suggests that pesticides like rotenone can induce alpha-synuclein accumulation in the gut and alter intestinal permeability, potentially contributing to the progression of PD pathology.
In addition to pesticides, industrial chemicals like trichloroethylene (TCE) and polychlorinated biphenyls (PCBs) have been implicated in neurodegenerative disorders. For example, TCE contamination at sites like Camp Lejeune has been linked to an increased risk of PD among exposed individuals. Similarly, PCBs persist in the environment, accumulate in the food chain, and are associated with elevated PD prevalence in specific populations.
Environmental Health Researcher, Dr. Philippe Grandjean stated, "Industrial chemicals like PCBs and TCE persist in the environment long after their use, infiltrating our food chain and posing a silent threat to neurological health." Dr. Beate Ritz, Epidemiologist and Environmental Health Scientist emphasizes, "Inhalation exposure provides a direct pathway for toxicants to reach the brain, potentially accelerating the onset and progression of neurodegenerative diseases like Parkinson's."
The Centers for Disease Control and Prevention (CDC) routinely monitor disease prevalence and trends. The agency's surveillance data corroborate the association between pesticide exposure and neurological disorders, revealing elevated rates of Parkinson's disease and dementia with Lewy bodies in regions with historical pesticide use, such as agricultural areas.
The National Institutes of Health (NIH) have funded numerous research projects investigating the neurotoxic effects of environmental pollutants. Studies funded by the NIH have elucidated the mechanisms by which pesticides and industrial chemicals induce neurodegeneration, providing crucial insights into the pathogenesis of Parkinson's disease and related disorders.
In late 2023, the EPA proposed a plan to ban all uses of TCE, commonly found in manufacturing and water sources globally. TCE has been widely used since the 1920s as a cleaning agent and degreaser in various industries, including metalworking, paints, sealants, and auto products. The proposed rule, if finalized, would phase out most commercial and consumer uses of TCE within a year, with limited exceptions for critical uses like battery manufacturing and superfund site cleanup. Studies have linked TCE exposure to cancer, liver damage, Parkinson’s, and reproductive issues. The EPA's move aligns with President Biden's Cancer Moonshot initiative and aims to protect public health and the environment.
While the precise mechanisms by which pesticides and industrial chemicals contribute to neurological disorders are still being elucidated, their continued presence in the environment raises significant public health concerns. Efforts to mitigate exposure to these toxicants, particularly among vulnerable populations, are crucial for preventing and managing neurodegenerative diseases.
