Arsenic is an element found in nature, and in man-made products, including some pesticides. Arsenic is widely distributed in the Earth’s crust. It is found in water, air, food, and soil.

Arsenic is highly toxic in its inorganic form.

Exposure to arsenic-laden drinking water can induce symptoms of gastroenteritis and lead to cancer, diabetes, and neurological and vasculardysfunction.

Long-term arsenic exposure in drinking water shows a dose-response relationship to carotid atherosclerosis. The mechanism involves the induction of expression of genes coding inflammatory mediators.

Arsenic has also been linked to dermatosis and cancers of the skin, bladder, and lung.

Dietary arsenic is contributed by various foods including cereals and breads (18.1%), starchy vegetables (14.9%), and meats and fish (32.1%) of total average daily intake.

Arsenic exposure is associated with the following clinical symptoms:

– Neurological: Central depression with visual effects, headache and high fever

– Hematological: Abnormal RBC counts, increased megalocytes and microcytes

– GI tract: Increased peristalsis with “rice water” stools

– Skin: “Milk and roses” complexion from vasodilation, darkening and degeneration.

Laboratory values of arsenic represent both the toxic form of arsenic and the non-toxic form of arsenic. Because seafood is rich in the non-toxic form of arsenic, the clinician should rule out ingestion of seafood in cases of borderline or moderate arsenic elevation before implementing aggressive therapy.

Urinary arsenic is most commonly measured to screen for arsenic exposure. Urine reflects arsenic exposure in the few days prior to specimen collection. To eliminate the contribution of seafood to total arsenic levels, avoid seafood 72 hours before test.

Hair, nail and urinary arsenic levels have been shown to be comparable. Hair or nail arsenic represents several months of exposure prior to taking the specimen. Hair arsenic greater than 1 μg/g dry weight has been taken to indicate excessive exposure.

Since elevated arsenic in the serum drops within 6 to 10 hours, serum is not the best specimen for determining chronic arsenic exposure. Whole blood is suitable for identifying acute exposure to arsenic, and high levels should be addressed immediately.