Heavy Metals

Heavy metal testing is used to screen for or to diagnose heavy metal poisoning in those who may have been acutely or chronically exposed to one or more heavy metals and to monitor excessive metal concentrations in those who work with various heavy metals. Testing is also conducted to monitor the efficacy of chelation therapy, a treatment to rid the body of high amounts of a heavy metal (e.g. iron).

Panels are set up in groups of tests that mirror potential metal exposures. A laboratory may offer several different groupings that are specific for either blood or urine. A doctor will request the most appropriate tests that correspond to the person's occupation, hobby, suspected exposure, and/or clinical symptoms. Some of the metals that are more commonly tested include:

• Lead
• Mercury
• Arsenic
• Cadmium
• Chromium and cobalt

If the doctor suspects that someone has been exposed to a specific metal, such as lead, the doctor may request that specific test instead of, or in addition to, a group of tests. Lead is usually requested by itself when screening for exposure, especially in children because of how susceptible they are to its effects. Some metals can also be measured in fluid, hair, fingernails, and body tissues. Usually these are requested individually.

Tests for heavy metals may be requested if a doctor suspects that someone has been acutely or chronically exposed to one or more heavy metals. Signs and symptoms of heavy metal exposure will vary in nature and intensity depending on the type and quantity of metal involved; early symptoms of poisoning can be missed because they are often non-specific. Excessive exposure and damage to several different organs can occur even if a person has no, few, or nonspecific symptoms. Some signs and symptoms of metal poisoning may include:

• Abdominal pain, nausea, vomiting and diarrhoea
• Nervous system symptoms such as numbness, tingling of hands and feet, weakness
• Anaemia
• Kidney damage
• Liver damage
• In the lungs – irritation, oedema
• Brain dysfunction, memory loss
• Mees lines (horizontal lines on nails)
• Changes in behaviour
• Malformed bones in children, weakened bones
• In pregnant women – miscarriage, premature labour

People who may be exposed to metals in the workplace are usually monitored periodically. Safety measures minimise risk to employees and help address problems when they are identified. In the UK, the Health & Safety Executive provides advice, guidance and legislation as an independent regulator of work-related health and safety issues. If excessive concentrations are detected, affected persons are monitored and steps are taken to reduce their exposure.

Care must be taken in the interpretation of heavy metals test results. A low level of a heavy metal in the blood does not necessarily mean that excessive exposure has not occurred. Heavy metals do not stay in the blood and will not be present in the urine for extended periods of time. Lead, for instance, migrates from the blood into the body's organs and over time is incorporated into the bones. If someone was chronically exposed to lead, then this may result in lead being present in the blood, urine, organs, and bones.

Very low levels of heavy metals may be present in the blood and urine of apparently healthy people because these metals are present within our environment. Recommendations for safe levels of heavy metals depend on the age of the person and may change over time as more information about their safety emerges.

To learn more about minimal risk levels and/or health effects of a particular metal, visit the Health & Safety Executive website. For advice about blood metal ion levels in hip replacements visit the MHRA or NHS choices websites.

Exposures to the same amounts and types of heavy metals will not necessarily lead to the same effects in different people because people absorb and eliminate metals at different rates. Those who have underlying health conditions may be more vulnerable than others to the same exposures.

Methylmercury, a form of mercury that is produced by bacteria in water, can build up in fish over time. Concentrations vary regionally and with the size of the fish. The highest levels are typically found in bigger and older fish. In most cases, the benefits of eating fish outweigh the small risk of ingesting excess mercury. However, women who are pregnant may want to take extra precautions. NHS choices recommend that pregnant women avoid or limit intake of certain types of fish during their pregnancy because of pollutants or mercury's potential harm to the foetus.

Lead was once routinely used in paint, plumbing pipes, and as an additive in petrol. In the UK, these environmental sources of lead have decreased, but it can be present in the existing paint and plumbing of older homes. When lead house paint deteriorates, it creates lead chips and dust that can be stirred up with the movement of air and can find their way into the soil around the house. While anyone may be harmed by lead exposure, children are at the highest risk. They may eat paint chips, mouth painted surfaces, breath in lead dust, and play in contaminated soil.

All of the sources of heavy metal exposure in the air, water and in the environment are controlled, regulated, and monitored by European and UK legislation. The Food Standards Agency may assess the level of heavy metals in certain foodstuffs and publish guidance in response to any concerns. The European Food Safety Authority and the European Commission are also involved in the investigation of any incidents and for issuing guidance to food manufacturers and industry.. The Environmental Agency (http://www.environment-agency.gov.uk/) is a leading public body for applying environmental standards. Regional water authorities are responsible for adhering to standards stated by the Water Supply Regulations/Drinking Water Inspectorate and can supply water quality information (including heavy metal levels) in local drinking water.

Heavy metal analysis is not done on a routine basis and is frequently performed at a reference laboratory, so the results are likely to longer to be returned to your doctor.