Neurodegenerative diseases and environmental risk factors: an overview of the available scientific evidence.

Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS) are among the most well-known and prevalent neurodegenerative disorders. These diseases result from an interaction between the environment and genetically predisposed individuals. This review examines the evidence available in the literature underlying this multifaceted interaction, focusing on various chemical substances such as metals, fertilizers, and herbicides, as well as toxic agents of microbiological origin, including cyanobacteria and their neurotoxins. In addition, the pathways through which toxic substances can enter the human body are discussed, such as air and water, which may lead to absorption through the lungs, the gastrointestinal tract, the skin, and mucosae. The routes by which neurotoxic substances gain access to the human body may help explain the increased risk of developing neurodegenerative diseases observed in sports played on soil and grass surfaces, such as soccer, American football, and golf.