Arsenic (chemical symbol As, atomic number 33) is a metalloid element found in soil, water, air, and food. It appears as inorganic species (commonly arsenite and arsenate) and as organic metabolites (including monomethylarsonic and dimethylarsinic acids and arsenobetaine in seafood). Historical and environmental monitoring has long focused on arsenic because of its persistent presence in some groundwater and industrial settings. In humans arsenic undergoes enzymatic methylation to produce metabolites that are excreted in urine. Clinical and environmental laboratories typically measure urinary arsenic using sensitive methods such as ICP-MS and may perform speciation to separate inorganic-derived metabolites from organic seafood-derived forms. Urine concentration, timing relative to exposure, and creatinine or specific gravity correction affect interpretation.

Elevated urinary arsenic can indicate recent or ongoing exposure sources such as contaminated drinking water, certain foods (notably some rice and sea products), occupational contact, or environmental contamination; high total arsenic can also reflect recent seafood intake when organic arsenicals are present. Elevated metabolite patterns (inorganic-related MMA/DMA) may reflect slower methylation or higher inorganic exposure. Low or undetectable arsenic generally suggests no recent exposure above background and effective recent clearance. Interpretation should consider speciation results, urine collection timing, kidney function, and detox-related genetics (methylation enzymes) as part of the full Toxin Zoomer profile rather than relying on a single value.

Arsenic is included in the Toxin Zoomer to quantify recent body burden and to help distinguish inorganic exposure from organic, seafood-related forms. When paired with detox-genetics and the broader toxicant panel, arsenic results help clinicians identify likely exposure routes (water, food, occupation) and whether an individual’s metabolic pattern may affect clearance, supporting more precise source-tracing and monitoring.