Arsenic Blood Test

Arsenic is a naturally-occurring element found in the earth's crust, mostly as organic (bound to hydrogen and carbon) and inorganic (bound to sulfur, oxygen, and chlorine) compounds. It also occurs as arsine gas (AsH₃). Organic forms are found mainly in shell fish and their predators (cod, haddock, etc.), and generally considered to be nontoxic. Inorganic forms are found in soil, sediment, and ground water; they are naturally-occurring or the result of mining, ore smelting, and industrial use.

The arsenicals are further classified according to valence states: Elemental (0) (very rare), arsenite (trivalent, +3), arsenate (pentavalent, +5), and arsine gas (-3). Inorganic forms of arsenic demonstrate high acute toxicity in humans, with trivalent inorganic arsenic (arsenite) being more toxic than pentavalent inorganic arsenic (arsenate). 

Acute, high-dose inorganic arsenic exposure can cause systemic toxicity and death. This type of toxicity is typically associated with accidental ingestion, industrial accidents (inhalation of gas), suicide, or homicide. 

Chronic toxicity occurs from a lower dose exposure over an extended time resulting in long-term subacute toxicity involving dermatologic, neurologic, GI, hepatic, cardiovascular, hematologic, respiratory, and endocrine systems. Chronic exposure increases cancer risk of skin, bladder, and lungs (WHO 2004).

Humans are typically exposed to organic arsenic by eating seafood. Sources of exposure to inorganic arsenic include leaching into drinking water (especially well water) from soil and rocks; various foods (rice products; juices; hijiki seaweed; meat from chicken treated with growth-promoter, roxarsone), exposure to wood preserved with arsenic, exposure to arsenic-containing pesticides, exposure to arsenic-containing chemicals used in hobbies (eg, glass making).

Diagnosis of arsenic toxicity is dependent on environmental and occupational exposure history, physical exam, and laboratory testing.