Arsenic Poisoning Test: Blood & Urine Guide (Canada)

An arsenic poisoning test is the most reliable way to confirm whether you have been exposed to dangerous levels of this toxic element. In Canada, healthcare providers use blood and urine testing to measure arsenic concentrations in the body, diagnose poisoning, and determine the right course of treatment. If you suspect exposure, understanding these tests is the first step toward protecting your health.

How the Arsenic Poisoning Test Works: Blood and Urine Methods

Arsenic enters the body through contaminated drinking water, certain foods, or airborne particles, and even low-level chronic arsenic exposure symptoms can develop gradually without warning. Because many Canadians rely on private well water that may contain naturally occurring arsenic, knowing when and how to get tested is essential. This guide breaks down how arsenic blood and urine tests work, what your results mean, and when you should speak with a doctor.

What Is Arsenic and Why Is It Dangerous?

Blood and Urine Arsenic Poisoning Test Results: Types and Clinical Management

Test Type	What It Measures	Normal Range (Health Canada)	Clinical Management
Whole Blood Arsenic Test	Total inorganic arsenic concentration in red blood cells; reflects recent or ongoing exposure within 2–4 days	Less than 20 µg/L	Levels above 60 µg/L require immediate medical evaluation; remove patient from exposure source and consult toxicology
24-Hour Urine Arsenic Test	Most reliable arsenic poisoning test; measures inorganic arsenic metabolites excreted over a full day	Less than 50 µg per 24 hours (adjusted for creatinine)	Levels above 200 µg/24 hr indicate significant exposure; chelation therapy (DMSA or DMPS) considered by specialist
Spot Urine Arsenic Test	Creatinine-corrected arsenic concentration; used for rapid screening when 24-hour collection is not feasible	Less than 35 µg/g creatinine	Positive results require confirmation with 24-hour urine; patient advised to avoid seafood 48 hours before re-testing
Hair and Nail Arsenic Analysis	Measures cumulative long-term arsenic exposure over weeks to months; useful for investigating chronic poisoning	Less than 1 µg/g dry weight	Elevated levels suggest chronic exposure; investigate environmental sources such as well water; report to local public health unit in Canada
Urine Arsenic Speciation Test	Distinguishes toxic inorganic arsenic from non-toxic organic forms (arsenobetaine) commonly found in seafood	Inorganic fraction less than 15 µg/L	Elevated inorganic fraction confirms true poisoning; organic-only elevation typically benign and dietary in origin; no treatment required

Arsenic is a naturally occurring element found in soil, water, and air. It exists in two main forms: organic and inorganic. Inorganic arsenic is far more toxic to the human body.

The trivalent form of inorganic arsenic is absorbed directly through the skin. It can be up to 60 times more toxic than the pentavalent form, which is absorbed through the intestines. Both forms can cause serious health problems with enough exposure.

In Canada, Health Canada monitors arsenic levels in drinking water and the environment to protect public health. However, exposure can still happen through certain occupations, contaminated well water, or even some foods.

How Does Arsenic Poisoning Happen?

Arsenic poisoning can occur in three main ways. You can swallow it, breathe it in, or absorb it through your skin or mucous membranes. Each route carries real health risks.

Common sources of exposure include:

• Contaminated drinking water, especially from private wells
• Certain seafood and shellfish, which contain organic arsenic
• Pesticides and industrial chemicals used in agriculture or manufacturing
• Soil at contaminated sites or near old mining operations
• Some traditional herbal remedies and supplements

Once arsenic enters the bloodstream, the body absorbs it into tissues quickly. As a result, blood levels may drop fast after exposure. The body then removes arsenic mainly through urine and stool over the following days.

Recognising the Symptoms of Arsenic Poisoning

Knowing the symptoms of arsenic poisoning can help you act quickly. Symptoms often appear within hours of significant exposure. Therefore, do not wait if you suspect poisoning.

Common symptoms include:

• Severe headaches or migraines
• Nausea and vomiting
• Diarrhoea and abdominal pain
• Low blood pressure (hypotension)
• Fever and chills
• Seizures or convulsions in serious cases

Chronic low-level exposure produces different symptoms. These may include skin changes, fatigue, numbness in the hands and feet, and an increased risk of certain cancers. The World Health Organization outlines the long-term health effects of arsenic exposure in detail.

Acute vs. Chronic Arsenic Exposure

Acute arsenic poisoning happens after a single large dose. It produces fast and dramatic symptoms. Chronic exposure, however, builds up slowly over months or years and may be harder to identify.

Both types require medical attention. If you live near an industrial area or rely on a private well, it is worth asking your family doctor about testing, even without obvious symptoms.

Arsenic Blood and Urine Tests: How They Work

Doctors use blood and urine tests to confirm arsenic poisoning and track how the body clears the toxin. Each test has a specific purpose and a best window of time for accurate results.

Blood Test for Arsenic

A blood test measures the level of arsenic circulating in your bloodstream. Normal blood arsenic levels are generally below 12 ng/mL. Levels above this threshold suggest recent or significant arsenic exposure.

However, blood levels rise and fall quickly. Arsenic moves from the blood into body tissues within hours. Therefore, a blood test is most useful very shortly after exposure occurs. After that window, results may appear normal even if poisoning happened.

Urine Test for Arsenic

The urine test is considered the most reliable method for detecting arsenic poisoning. Because the kidneys filter arsenic through a process called glomerular filtration, arsenic shows up in urine for a longer period than in blood.

A 24-hour urine collection is often requested for the most accurate measurement. This means collecting all urine produced over a full day and night in a special container. Your healthcare provider will give you clear instructions on how to do this correctly.

The laboratory uses a method called inductively coupled plasma mass spectrometry, or ICP-MS. This is a highly sensitive technique that can detect even very small concentrations of arsenic and other heavy metals in body fluids.

Monitoring Treatment Progress

These tests are also used after treatment begins. Repeat urine testing helps doctors confirm that arsenic levels are falling as expected. This ensures that treatment, which may include a medication called chelation therapy, is working effectively.

How to Prepare for Your Arsenic Test

Proper preparation is important for accurate results. Certain foods and supplements can raise arsenic levels in your urine, even without true poisoning. Following these steps will help your healthcare team get a clear picture.

Before your test, you should:

• Avoid fish and seafood for at least 72 hours before the test. Seafood contains organic arsenic that is not harmful but will show up on the test and distort results.
• Stop taking vitamins, minerals, and over-the-counter supplements as directed by your doctor. Many supplements contain trace minerals that can interfere with results.
• Tell your healthcare provider about all prescription medications you take.
• Follow any additional instructions given by your lab or clinic.

If you are unsure about what to stop taking, call your family doctor’s office or the laboratory directly before your appointment. It is always better to ask than to risk an inaccurate result.

Understanding Your Test Results

Getting your results can feel confusing without context. Here is a simple guide to help you understand what the numbers may mean.

Blood Arsenic Levels

A blood arsenic level above 12 ng/mL is considered abnormal. This suggests recent exposure or active arsenic poisoning. However, because blood levels drop quickly, a normal result does not always rule out poisoning if time has passed.

Urine Arsenic Levels

Urine arsenic results are usually reported in micrograms per litre (µg/L) or micrograms per gram of creatinine. Your doctor will interpret these numbers based on your symptoms, your history of exposure, and the timing of the test.

In addition, your doctor will consider whether you followed the seafood restriction before the test. Eating shrimp or shellfish within three days of testing can significantly raise urine arsenic levels and lead to a false positive result.

Factors That Can Affect Results

Two substances are known to interfere with heavy metal testing, including arsenic. High levels of gadolinium, used in MRI contrast dye, and iodine can distort most heavy metal test results. Tell your doctor if you recently had an MRI with contrast or if you use iodine-containing products.

When to See a Doctor About Arsenic Poisoning

If you think you or a family member has been exposed to arsenic, seek medical help promptly. Do not wait for symptoms to worsen. Time matters, especially in acute arsenic poisoning cases.

You should contact a healthcare provider if you:

• Have sudden nausea, vomiting, or diarrhoea with no clear cause
• Experience seizures, confusion, or a sudden drop in blood pressure
• Work in an industry that uses arsenic or related chemicals
• Drink water from a private well that has never been tested
• Have unexplained skin changes, fatigue, or numbness over a long period

In Canada, you have several options for getting help. Your family doctor is always a good first step for non-emergency concerns. If your family doctor is unavailable, a walk-in clinic can order initial blood and urine tests. For serious symptoms like seizures or very low blood pressure, go to your nearest emergency department or call 911 immediately.

Provincial health plans across Canada generally cover testing for arsenic poisoning when ordered by a physician. Check with your provincial health authority or ask your doctor about coverage in your province or territory.

The Mayo Clinic provides a helpful overview of arsenic poisoning symptoms and causes that you can review before your appointment.

Frequently Asked Questions About Arsenic Poisoning

Key Takeaways

• Arsenic poisoning can occur through swallowing, inhaling, or skin contact with arsenic-containing substances.
• Inorganic arsenic is the most toxic form and can be absorbed through the skin or digestive tract.
• Symptoms include nausea, vomiting, diarrhoea, abdominal pain, low blood pressure, fever, and seizures.
• Blood tests detect arsenic shortly after exposure, but urine testing is the most reliable method overall.
• The ICP-MS laboratory method provides highly accurate measurements of arsenic in body fluids.
• Avoid fish, seafood, vitamins, and certain supplements for at least 72 hours before testing.
• High levels of gadolinium or iodine in the body can interfere with heavy metal test results.
• In Canada, your family doctor, a walk-in clinic, or an emergency department can order and interpret these tests.
• Always consult a qualified healthcare provider before drawing conclusions from any test results.

According to Health Canada’s guidelines on arsenic in drinking water, this information is supported by current medical research.

For more information, read our guide on learn more about urinary testing for Canadians.

This article is for informational purposes only and does not replace professional medical advice. Always speak with your family doctor or a qualified healthcare provider if you have concerns about arsenic exposure or any other health condition.