Mercury testing is carried out to detect the presence of an excessive amount of mercury within the body. It may be requested by your doctor to determine whether you have been acutely or chronically exposed to increased concentrations of mercury. It may also be requested to monitor those who are exposed to mercury in the workplace.
More than one type of sample may be collected and tested.
Blood is primarily tested to detect the presence of methyl mercury. Other forms of mercury can also be detected in the blood, but according to the Agency for Toxic Substances and Disease Registry (ATSDR), the amount present in blood will decrease by a half every 3 days as the mercury moves into other organs such as the brain and kidneys. Blood testing must be done within days of suspected exposure.
Urine is used to test for metallic mercury and inorganic forms of mercury, but it cannot be used to determine exposure to methyl mercury.
Hair testing may be useful to detect methyl mercury exposures that occurred several months previously, but hair testing is relatively complex and is not used frequently.
Although not routinely requested tests,mercury has been shown to be present in nails, breast milk, stool, and breath.
Mercury testing may be performed when a patient has symptoms suggesting excessive exposure to mercury. Acute symptoms may include:
burning in the mouth and lungs
cough, difficulty breathing, chest tightness
decreased urine output
nausea, vomiting, diarrhoea
increased heart rate
Those who are chronically exposed to mercury may have non-specific symptoms that involve the lungs, kidneys, and nervous system. Some of the chronic symptoms may include:
problems with hearing, taste and smell
blurred vision or sometimes tunnel vision
tingling or tremors in the arms or legs
Testing may also be performed when a patient is known to have been exposed to mercury, in order to help evaluate the extent of the exposure. Mercury measurements may be requested regularly as a monitoring tool for those patients who work in industries that utilise mercury and may be requested, along with lead and/or other heavy metals, for individuals who work with a variety of potentially hazardous materials.
Normal concentrations of mercury in blood and urine indicate that it is unlikely that the patient has been exposed to excessive levels of mercury, at least not in the window of time that the test is measuring.
Elevated concentrations of mercury in blood or urine indicate that excessive exposure to mercury has occurred, but it does not indicate the form or quantity of mercury to which a person was exposed. Increased blood concentrations suggest a relatively recent exposure to mercury, while a 24-hour urine sample gives more of an average past history of exposure to metallic or inorganic mercury.
Increased concentrations of mercury in hair may indicate exposure to increased concentrations of methyl mercury but hair samples are rarely used because of issues involving testing standardisation, sample contamination and the fact that hair is subject to many pre-analytical variables (hair exposure to dyes, bleach, shampoo, etc.).
Mercury is considered to be a non-essential trace element in humans, therefore low levels of mercury are usually not of any concern.
Measures have been taken in recent years to reduce and control the public’s exposure to mercury. Stricter regulations and recommendations have lowered the amounts allowable in the air, water, soil, food and in the workplace.
The high concentrations of mercury found in certain fish may harm the developing nervous systems in unborn babies and young children. The FDA recommends that pregnant women, women who may become pregnant, young children and nursing mothers avoid eating shark, swordfish, king mackerel and tilefish.They advise these groups to eat fish that are usually found to have lower levels of mercury such as canned light tuna, shrimp or salmon.
This article was last reviewed on 8 December 2011. | This article was last modified on 8 December 2011.
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