Amantadine is an antiviral and antiparkinson drug, which was exclusively found in the two PD groups (iPD and PD+/LRRK2+), as expected. This trend was consistent for both dust and serum samples (Figure ). Furthermore, levodopa, the most commonly prescribed medication for first-line therapy in PD, was found solely in the household dust of PD participants (iPD and PD+/LRRK2+, Table for details) . Importantly, the intake of amantadine, levodopa, and other dopaminergic drugs (exclusively in the PD groups) may influence the metabolism, and consequently the observed results in the serum samples.