Ask The Doctor: Mercury Exposure

My family doctor tested my blood for heavy-metal poisoning and told me he saw no sign of lead or mercury. I’ve since heard that the test he used may not be very accurate. Should I get retested?
By Paul S. Anderson, ND

You bring up an excellent question, and I hear it at my clinic almost weekly. Your experience at the doctor’s office mirrors the typical approach to heavy-metal testing—if the physician tests you at all.

Mercury and lead constitute the principal heavy metals to which people are exposed. Two basic types of exposure exist: acute and chronic. The former occurs if, for example, you eat or drink contaminated food or water or sand a lead-painted surface. Shortly afterward, the levels of toxins in your blood increase. Simple blood tests will, at first, show that increase. After the heavy metals circulate in the blood, however, they slowly deposit throughout the body. At that point, the metals won’t show up on a blood test.

Solid organs like the liver, brain, and spleen hold on to the metal for quite some time, often years, which can lead to myriad problems, among them organ dysfunction, memory troubles, lowered immunity, and chronic pain. Your bones generally retain toxic metals the longest. The bone matrix is very adept at holding on to ionic substances (like minerals and metal) for life. Since the body has no use for toxic metals in any physiological process, depositing it in bone at least keeps it out of circulation. Thanks to food and product safety standards, acute exposures are fairly rare.

Chronic exposures to metals follow the same pathway; you just ingest or inhale smaller quantities over longer periods of time. These repeated exposures subject your circulatory system and organs to several bouts with the toxins. While no firm statistics exist on chronic metal toxicity in the US, physicians who check their patients for toxicity commonly see it. The same health problems that accompany acute exposure can also afflict those with chronically toxicity.

The blood test your physician chose works great for recent, acute exposures, but it doesn’t detect metals once they’re embedded in the organs. To skirt that limitation, many physicians test in other ways, including hair testing, which screens for long-term exposure to metals, such as lead and arsenic (other toxins in hair may not be very reliably tested), and urine testing. The latter entails taking a provoking agent that travels through the body removing some of the metal from organs; the metals then exit in the urine where they’re detected and their levels are measured.

Naturopathic physicians and others who specialize in environmental medicine can help you decide which testing method is right for your particular history. If you’re acutely exposed to heavy metals, seek the immediate help of a medical toxicologist through your local hospital. If you’ve experienced chronic exposure and received a diagnosis, follow your naturopathic or environmental physician’s protocols for detoxification.

Common Culprits

Behind acute exposure:
Lead paint
Melting alloy (bullet reloading, fishing weights, glass blowing, and soldering)
Toxic food (mainly in third-world countries)

Behind chronic exposure:
Fish high in mercury (shellfish, river-dwelling fish, canned tuna)
Dental amalgams
Water (many sources are clean for lead and mercury but high in arsenic)
Some food sources (watch imported foods, especially Chinese)
And the one few people think of: fetal exposure (for example, if your mother was exposed to any of the above sources while you were in the womb)