How long does arsenic stay in blood after exposure?

The half-life of inorganic arsenic in blood is only 4 to 6 hours, while methylated metabolites have a half-life of 20 to 30 hours. This means blood testing is most effective within 1-2 days of exposure. For longer-term exposure assessment, urine testing or hair/nail analysis may be more appropriate.

Should I avoid certain foods before the test?

Yes, patients should avoid shellfish and seafood for 48 to 72 hours before testing, as seafood contains high concentrations of protein-bound arsenic that is not harmful but may lead to elevated total arsenic levels. This dietary arsenic can interfere with the interpretation of results for toxic exposure.

What are common sources of arsenic exposure?

The largest source of arsenic exposure worldwide is contaminated drinking water, with crops irrigated with contaminated water and food prepared with contaminated water being additional sources. Occupational exposure can occur in industries including pesticides and herbicides, smelting and mining, glass manufacturing, semiconductor manufacturing, and woodworking.

What symptoms might indicate arsenic poisoning?

Immediate symptoms of arsenic poisoning include nausea, vomiting, abdominal pain, and diarrhea. These may be followed by numbness and tingling of the extremities, muscle cramping, and in chronic cases, skin changes such as darkening and lesions. If you experience these symptoms after potential exposure, seek medical attention promptly.

Is blood testing better than urine testing for arsenic?

Blood is not considered a good specimen to screen for arsenic exposure, and urine is the preferred specimen for assessment of arsenic exposure. Blood testing is primarily useful for very recent exposure (within 1-2 days), while urine testing is better for detecting exposure over the past few days to weeks. The choice depends on the timing of suspected exposure.

Can workplace exposure be detected with this test?

Yes, this test can detect recent occupational arsenic exposure, particularly useful for workers in high-risk industries. The Biological Exposure Index established for workers is 35 μg/L for the sum of inorganic arsenic and methylated metabolites. However, for ongoing workplace monitoring, regular testing may be needed due to arsenic's short half-life in blood.

Toxicology

Arsenic (Blood)

Measures arsenic levels in blood to detect recent exposure to this toxic heavy metal, useful for occupational or environmental monitoring.

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Blood

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What this test measures

This test measures the total concentration of arsenic in blood. Arsenic is a naturally occurring metalloid found in rock, soil, and groundwater, and human exposure can occur through contaminated drinking water, certain foods (rice and seafood are notable sources), cigarettes, occupational environments, and industrial air emissions. Arsenic exists in both organic and inorganic forms, with inorganic arsenic posing the greater health risk and recognized as a significant carcinogenic factor.

Blood arsenic testing is most useful for detecting acute or very recent exposure because arsenic clears from the bloodstream quickly. Inorganic arsenic has a blood half-life of only 4 to 6 hours, and its methylated metabolites have a half-life of 20 to 30 hours. This means blood arsenic may not be detectable in samples drawn more than two days after the last exposure. For assessing chronic or ongoing low-level exposure, urine arsenic testing is generally more informative. Healthcare providers order the blood test when acute poisoning is suspected or when a recent exposure event needs to be confirmed.

Who should consider this test

You might consider this test if you are experiencing any of the following:

Individuals who work in industries that use or produce arsenic-containing materials, including smelting, mining, semiconductor manufacturing, glass production, or wood preservation.
Those living near industrial areas or former industrial sites where arsenic contamination may have occurred.
People with suspected recent arsenic exposure from contaminated drinking water, especially those using private wells in areas known for high groundwater arsenic levels.
Individuals experiencing symptoms that may suggest arsenic poisoning, such as severe gastrointestinal symptoms, skin changes, or neurological symptoms after potential exposure.
Workers in agriculture or landscaping who may be exposed to arsenic-containing pesticides or treated wood products.

What to expect

Preparation

Avoid eating seafood, fish, or shellfish for 48-72 hours before the test, as these foods naturally contain organic arsenic that can affect results. Discontinue nutritional supplements and vitamins if advised by your healthcare provider. No fasting is required.

Sample Type

A standard blood draw is performed using a special royal blue-top collection tube to prevent contamination from trace metals.

Collection

The blood sample is collected through a quick venipuncture procedure at the testing location and sent to the laboratory for analysis using specialized equipment.

Turnaround

Results are typically available within 1-3 business days after the laboratory receives your sample.

Understanding your results

Blood arsenic concentrations in unexposed individuals are typically well below 12 ng/mL, and levels should not exceed 50 mcg/L. Values above 12 ng/mL indicate significant exposure, but will only be detected if the sample is drawn soon after the exposure event due to arsenic's rapid clearance from blood. A normal blood arsenic level does not rule out chronic low-level exposure, since the metal redistributes to tissues and is excreted in urine relatively quickly. Healthcare providers interpret results alongside symptoms, exposure timeline, urine arsenic levels when available, and clinical context to determine whether further evaluation or treatment is appropriate.

Population	Reference Range	Notes
Adults (all ages)	< 12 ng/mL (< 12 μg/L)	Normal background level with no significant recent exposure
Adults (unexposed)	0.3-2 μg/L	Typical range in individuals with no known arsenic exposure

Reference ranges may vary by laboratory and individual factors. Results should be interpreted by a healthcare provider in the context of your overall health.

What does a “Low” result mean?

Low or undetectable arsenic levels in blood typically indicate no recent significant exposure to arsenic. This is the expected result for individuals without occupational or environmental arsenic exposure. Blood is not considered a good specimen to screen for arsenic exposure, and urine is the preferred specimen for assessment of arsenic exposure.

What does a “High” result mean?

Elevated blood arsenic levels commonly range from several hundred to several thousand micrograms per liter in patients with arsenic poisoning. High levels may indicate recent exposure and can cause immediate symptoms including nausea, vomiting, and diarrhea, with long-term exposure potentially causing skin changes such as darkening and lesions. Potentially toxic ranges for blood arsenic are considered to be greater than or equal to 600 μg/L.

Privacy & confidentiality

Your arsenic test results are completely confidential and protected under HIPAA regulations. Results are not shared with employers, insurance companies, or added to your medical records unless you specifically request it. No doctor visit is required to order this test.

Frequently asked questions

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Last reviewed: April 2026

CPT Code: 83015, 82175

This test may not be available in: NY, NJ, RI

This page is for informational purposes only and does not constitute medical advice. Always consult with a healthcare provider regarding any health concerns. LevelPanel does not diagnose, treat, or prescribe.

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This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.

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