Heavy Metals
The Test
How is it used?
If your doctor suspects that you have been exposed to a specific metal, such as lead, then she may order that specific test instead of or in addition to a panel. Lead is usually ordered by itself when screening for exposure in young children. Some metals can also be measured in fluid, hair, fingernails, and body tissues. Usually these are ordered individually.
A zinc protoporphyrin (ZPP) test may be ordered, along with a lead level, to test for chronic lead exposure in adults. However, it is not as widely ordered by doctors as in the past. The ZPP test result increases with lead exposure because lead interferes with the red blood cells' ability to make hemoglobin. It reflects an average of lead exposure over time but not recent exposure. However, it does not usually become abnormal until the lead concentration is greater than 25 micrograms per deciliter. Because values do not rise until lead concentrations exceed the acceptable range, ZPP is not sensitive enough for use as a screening test in children.
Other tests, such as a Complete Blood Count (CBC) to evaluate blood cells and check for anemia or a Comprehensive Metabolic Panel (CMP) to evaluate body organ function and electrolyte balance may be ordered along with metal analysis to evaluate a person’s general state of health.
When is it ordered?
- Abdominal pain, nausea, vomiting, and diarrhea
- Nervous system symptoms such as numbness, tingling of hands and feet, weakness
- Anemia
- Kidney damage
- Liver damage
- In the lungs – irritation, edema
- Brain dysfunction, memory loss
- Changes in behavior
- Malformed bones in children, weakened bones
- In pregnant women – miscarriage, premature labor
People who may be exposed to metals in the workplace are usually monitored periodically. Safety measures are in place to minimize the risk to employees and to address problems when they are identified. The U.S. Occupational Safety and Health Administration (OSHA) regulates the use and monitoring of thirty-five toxic metals that may be found on the job. If excessive concentrations are detected, the affected person will be monitored as steps are taken to reduce their exposure.
What does the test result mean?
Very low levels of many heavy metals may be present in the blood and urine of apparently healthy people because these metals are present throughout 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 ToxFAQs™ section of the Agency for Toxic Substances and Disease Registry (ATSDR) website.
Is there anything else I should know?
Exposures to the same amounts and types of heavy metals will not necessarily lead to the same effects in different people. People absorb and eliminate metals at different rates. Those who have underlying health conditions may be more vulnerable than others to the same exposures. Depending on symptoms or tests results from a certified laboratory, those with levels higher than what is considered to be safe may consider chelation therapy. Chelation therapy is a treatment to rid the body of high amounts of a heavy metal.
Trace concentrations of heavy metals are monitored and minimized but are almost impossible to avoid altogether. For instance, naturally-occurring arsenic is a contaminant that can be found in some sources of drinking water throughout the world. Small amounts of mercury are found in fluorescent light bulbs and some thermometers. If these break, the mercury can be released. Methyl mercury, an organic 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. The March of Dimes recommends that pregnant women avoid certain types of large fish during their pregnancy because of mercury’s potential harm to the fetus.
Lead was once routinely used in paint, plumbing pipes, and as an additive in gasoline. In the U.S., these environmental sources of lead have decreased, but it can be present in the existing paint and plumbing of older homes and is sometimes present in the paint of imported toys or jewelry. 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, food supply, and in the environment are controlled, regulated, and monitored by both governmental agencies and the medical community. The Environmental Protection Agency (EPA) evaluates the effects of exposures, regulates industrial emissions, and establishes maximum contaminant levels for heavy metals such as arsenic in drinking water. The Food and Drug Association (FDA) establishes limits for metals in food, and the Centers for Disease Control and Prevention (CDC) recommends testing young children for lead, especially for those who live in or routinely visit a house built before 1950.
