Table 1:

Examples of triggers proposed to spark PD pathogenic process.

Triggers	Examples	References
Gastrointestinal microbiota perturbations	Increased Lactobacillus	[21]
	Reduced Prevotella	[21]
Pathogens	Hepatitis B and C	[75]
	Norovirus	[11]
	M. paratuberculosis	[53]
Air pollution	Particulate matter	[76]
	Carbon monoxide	[76]
Pesticides	Rotenone	[23]
	Paraquat	[23]
Heavy metals	Iron	[77]
	Copper	[77]
	Manganese	[77]
Head trauma	Traumatic brain injury	[78]