A urine arsenic test measures how much arsenic your body is passing in the urine, reported in micrograms per litre (µg/L). Because the body clears absorbed arsenic mainly through the kidneys, this test is the standard way to gauge recent exposure. Most laboratories treat a result under 35 µg/L as within the usual reference range, with higher numbers pointing to greater or more recent exposure that deserves a closer look.
What is the urine arsenic test?
Arsenic is a naturally occurring metalloid found in rock, soil and water. It has no useful role in the human body. When arsenic is swallowed or inhaled it enters the bloodstream and is filtered out by the kidneys over the following hours and days, which is why a urine sample captures exposure so well. Blood arsenic clears very quickly, so urine is the preferred sample for assessing recent contact.
A doctor may order a urine arsenic test when there is a reason to suspect exposure — for example symptoms that fit chronic arsenic toxicity, a known contaminated water source, or a workplace that handles arsenic. It is also used to monitor people already identified as exposed, to see whether levels fall once the source is removed.
In India, the single most important source is contaminated groundwater. Arsenic occurs naturally in the aquifers of several regions — parts of West Bengal, Bihar and Assam along the Ganga–Brahmaputra plains are well recognised — where tube-well and borewell water drawn for drinking and cooking can carry arsenic well above safe limits. Because the water often looks, smells and tastes normal, families can be exposed for years without warning. Occupational sources add to this: work involving smelting and metal processing, glass manufacturing, certain pesticides and wood preservatives, and some mining and electronics processes can raise exposure.
The test is usually done on a urine sample, sometimes collected over 24 hours for greater accuracy. One practical point matters for interpretation: eating seafood shortly before the test can raise the measured arsenic, because fish and shellfish contain relatively harmless organic forms of arsenic.
Urine arsenic normal range
The result is a single number in µg/L. A value under 35 µg/L is generally treated as the normal reference range. As with any heavy-metal exposure marker, a lower result is better, and the goal is to keep exposure as close to zero as possible. The bands below show how ExaHealth grades a urine arsenic result:
| Urine arsenic (µg/L) | ExaHealth band |
|---|---|
| 0–35 | Normal (reference range) |
| 36–50 | Borderline / raised |
| 51–100 | Moderately high |
| 101–200 | Severely high |
| 201–500 | Critically high |
Always read your own report's printed reference range, because methods, sample type (spot versus 24-hour) and cut-offs vary between Indian laboratories. Two points help when interpreting the number. First, a result can be raised simply because of a recent seafood meal, so a high value is often rechecked after a few days of avoiding fish and shellfish. Second, better laboratories can separate total arsenic from the inorganic arsenic that actually reflects harmful exposure — this distinction, discussed below, is what makes a raised total result meaningful or reassuring.
Normal range by age, sex and condition
The same numeric reference — under 35 µg/L — is applied across ages and sexes, so there is no separate set of normal numbers for different groups. What changes is how a result should be interpreted, and how vulnerable a person may be to the same exposure. The table below is qualitative; it does not assign different cut-offs, because none are established for these groups.
| Group or situation | Why interpretation or vulnerability differs |
|---|---|
| Recent seafood eaters | Fish, shellfish and seaweed contain organic arsenic (largely arsenobetaine) that is relatively harmless and passes in the urine, transiently raising total arsenic. A raised result is usually rechecked after avoiding seafood for a few days. |
| Infants and young children | The developing brain and nervous system are more sensitive to arsenic, and children drink more water and eat more food per kilogram of body weight, so the same contaminated source affects them more. |
| Pregnant women | Arsenic can cross the placenta, so exposure during pregnancy is taken seriously and a contaminated water source warrants prompt attention. |
| People in known arsenic-affected areas | Residents of arsenic-endemic regions such as parts of West Bengal, Bihar and Assam may carry higher levels from long-term groundwater exposure; results are read together with the household's water source. |
| Occupationally exposed adults | Workers in smelting, glass, pesticide, wood-preserving and some mining or electronics processes may show higher levels; workplace monitoring interprets results against exposure over time rather than a single number. |
| People with reduced kidney function | Because arsenic is cleared by the kidneys, impaired kidney function can affect how the marker behaves, so results are interpreted alongside overall kidney health. |
Because these differences are about susceptibility, recent diet and context rather than different numbers, every result is best read together with the person's likely sources of exposure, recent seafood intake and symptoms, and interpreted by a doctor — with young children and pregnant women given the greatest caution.
What high urine arsenic means
A raised urine arsenic level means the body has recently absorbed more arsenic than it should, usually because of an ongoing or recent source. The most common innocent explanation is a seafood meal in the days before the test; once that is excluded, a persistently high result points to a genuine exposure — most often contaminated drinking water, sometimes an occupational or dietary source. The higher the number, and the more it reflects inorganic arsenic, the greater the concern and the more urgent the need to find and remove the source.
Short-term high-dose exposure can cause nausea, vomiting, abdominal pain and diarrhoea. The greater worry in India, however, is chronic low-level exposure from contaminated water over years, which typically shows up in the skin. Recognised features of long-term arsenic toxicity include:
- Skin changes: thickening of the skin on the palms and soles (hyperkeratosis), and patchy darkening or spotty pigmentation of the skin — often the earliest visible signs.
- General symptoms: tiredness, weakness, tingling or numbness in the hands and feet from nerve involvement.
- Longer-term risk: chronic arsenic exposure is an established human carcinogen and raises the long-term risk of certain cancers, including cancers of the skin, bladder and lung, as well as effects on the heart, blood vessels and other organs.
Because arsenic can affect several systems, a raised result may prompt your doctor to check related areas — for example a kidney function panel, since the kidneys both clear arsenic and can be affected by it. Where more than one heavy-metal exposure is possible, doctors sometimes check other metals alongside arsenic, such as a blood lead level or blood cadmium. The single most important step for any genuinely raised level is identifying and eliminating the source, especially the drinking-water supply; any treatment decisions belong entirely to your doctor.
What low urine arsenic means
For arsenic, low is exactly what you want. Because the body has no need for arsenic, the ideal result is as close to zero as possible, and a low number is reassuring — it suggests little recent exposure. There is no such thing as a urine arsenic level that is "too low"; unlike nutrients such as iron or vitamin B12, arsenic has no deficiency state and no beneficial minimum.
One caveat is worth remembering: a urine arsenic result reflects mainly recent exposure. A low reading is reassuring about the present, but it does not prove that a water source is safe for the long term. If the household still draws water from an untested tube-well in an arsenic-prone area, levels can rise again with continued use, so confirming the water is safe matters even when a current reading looks fine.
How to reduce arsenic exposure and protect your family
You cannot "detox" arsenic away with diet or supplements, and there is no home remedy for arsenic toxicity — the only reliable approach is to stop the exposure and let a doctor guide any treatment. Practical, evidence-aligned steps include:
- Test and treat your water. If you live in or near an arsenic-affected region such as parts of West Bengal, Bihar or Assam, have your tube-well or borewell water tested. Use a verified safe source or an arsenic-removal treatment for drinking and cooking. Boiling does not remove arsenic and can concentrate it slightly.
- Use safe water for cooking too. Rice and other foods absorb arsenic from the water they are cooked in, so use tested, safe water for cooking as well as for drinking.
- Interpret seafood results sensibly. If a test comes back high and you ate fish or shellfish beforehand, ask your doctor whether to repeat it after a few days of avoiding seafood, ideally with inorganic arsenic measured separately.
- Mind occupational exposure. If you work with smelting, glass, pesticides, wood preservatives or similar processes, follow workplace safety measures, and change and wash so you do not carry dust home to your family.
When to see a doctor: if your drinking water comes from an untested well in an arsenic-prone area, if you notice thickening or darkening of the skin on your palms and soles, or if you have unexplained tingling, numbness or persistent tiredness with possible exposure. Tracking a urine arsenic level over months — as a water source is corrected — shows whether it is falling; keeping all your reports in one place with ExaHealth makes that trend easy to follow. Explore more explainers in our lab tests library.
Guidelines and references
The interpretation here follows standard laboratory reference ranges and long-established public-health understanding of arsenic:
- Standard laboratory reference ranges for urine arsenic — your own laboratory's printed reference range is the definitive cut-off for your result.
- World Health Organization (WHO) — the global public-health body whose guidance underpins the recognition of arsenic in drinking water as a major health hazard and a known human carcinogen.
Urine arsenic is often considered alongside other heavy-metal and organ-function tests — see our guides to blood lead level, blood cadmium and kidney function tests.
Frequently asked questions
What is a normal urine arsenic level?
A urine arsenic result under 35 µg/L is generally treated as the normal reference range. Because arsenic has no useful role in the body, lower is always better, and the number reflects mainly recent exposure rather than a lifetime total.
Why can seafood raise a urine arsenic result?
Fish, shellfish and seaweed contain organic forms of arsenic, mainly arsenobetaine, that are relatively harmless and pass out in the urine. A seafood meal in the days before the test can therefore raise total urine arsenic temporarily, so a high result is often rechecked after avoiding seafood.
What are common sources of arsenic exposure in India?
The most important source is naturally contaminated groundwater from tube-wells and borewells, especially in parts of West Bengal, Bihar and Assam. Occupational sources such as smelting, glass manufacturing, some pesticides and wood preservatives can also raise exposure.
What health problems does chronic arsenic exposure cause?
Long-term arsenic exposure typically shows in the skin as thickening of the palms and soles and patchy darkening or pigmentation, and can cause tingling or numbness in the hands and feet. Over many years it also raises the risk of certain cancers, including skin, bladder and lung cancer.
How is a urine arsenic test done?
It is done on a urine sample, sometimes collected over 24 hours for greater accuracy. Because recent seafood can raise the reading, doctors often advise avoiding fish and shellfish for a few days beforehand, and better laboratories can measure the harmful inorganic arsenic separately.
How can I lower a high urine arsenic level?
The essential step is to find and remove the source, most often by testing your drinking water and switching to a safe or arsenic-treated supply for both drinking and cooking. You cannot detox arsenic away with diet, and any treatment decisions are made by your doctor based on how high the level is.