Do arsenic and thallium cause fatigue by impairing mitochondrial oxidative phosphorylation?

An evidence-based assessment of the effects of arsenic and thallium on mitochondrial function and fatigue reveals the following findings:

Mechanistic evidence of mitochondrial toxicity

Arsenic and thallium disrupt mitochondrial oxidative phosphorylation and deplete cellular energy through distinct, highly potent biochemical mechanisms:

• Arsenic-induced impairment: Arsenic directly blocks key steps of cellular respiration. Trivalent arsenicals bind to the reduced lipoic acid cofactor of pyruvate dehydrogenase (PDH), halting the transition from glycolysis to the tricarboxylic acid (TCA) cycle. Additionally, inorganic arsenate acts as a phosphate analog, substituting for phosphate during ADP phosphorylation to form unstable ADP-arsenate complexes—a process known as arsenolysis that uncouples oxidative phosphorylation. Arsenic also directly inhibits Complex I and Complex II of the electron transport chain (ETC), collapsing the mitochondrial membrane potential and downregulating mitochondrial biogenesis via PGC-1α.
• Thallium-induced impairment: Thallium (Tl⁺) acts as a structural analog to potassium (K⁺) due to their near-identical ionic radii. It enters the mitochondria through K⁺ channels, dissipating the essential mitochondrial membrane potential. Once inside the matrix, thallium binds to sulfhydryl groups on respiratory chain enzymes, inhibiting complexes and preventing ATP synthase from driving ATP production.

Clinical and physiological evidence linking ATP depletion to fatigue

Impaired oxidative phosphorylation and the resulting ATP depletion directly manifest as systemic fatigue:

• Clinical correlation: Studies in patients with primary mitochondrial diseases (such as those carrying the m.3243A>G mutation) and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) demonstrate that cellular bioenergetic deficits—measured via decreased ATP-linked respiration, lower basal ATP levels, and impaired ADP/ATP translocase activity—strongly correlate with subjective fatigue severity and functional limitations.
• Physiological burden: When heavy metal toxicity impairs mitochondrial respiration, cells are unable to meet basic bioenergetic demands. The body's inability to match ATP supply with demand in skeletal muscle and central nervous system tissues results in the clinical presentation of chronic fatigue and post-exertional malaise.

Bottom line

The claim is supported by science. Arsenic and thallium act as direct mitochondrial toxicants that block pyruvate dehydrogenase, dissipate mitochondrial membrane potential, and inhibit respiratory complexes. This acute and chronic impairment of oxidative phosphorylation and ATP synthesis directly correlates with, and clinically manifests as, systemic fatigue.