Diagnosis: Mercury

Money, Politics, and Poison

ISLAND PRESS

Contents

The Discovery

I HAVE A VIVID MEMORY as a young child in the 1970s of my mother asking me to look in the cupboards and pull out all of the canned tuna she had stored there. Together we checked numbers on the cans to see if they were on a recall list. I didn't know at the time why the cans were being recalled, or even why, really, we were removing the cans from our shelves.

I hadn't thought about that event in decades, not until a few years ago when I found myself trying to make sense of the complaints of a series of patients in my San Francisco medical practice. In the early 1970s the U.S. Food and Drug Administration (FDA) had decided that the amount of mercury in some of the fish then being canned posed a health risk to consumers. The concern died down, so somehow, the fisheries industry must have been able to resolve the problem. Or did it?

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One morning in January 2000, a patient I shall call Toshiko came to see me complaining of an array of puzzling symptoms. A soft-spoken but serious businesswoman of Japanese descent in her mid-forties, Toshiko lived some miles away and traveled the world frequently. On her way back from Japan the previous week, she said she had fainted in the restroom on the plane. She had some nausea but no vomiting and still did not feel well.

Over the next hour I asked Toshiko my usual list of questions as an independent practitioner of internal medicine. This was the second time she had fainted recently, it turned out. And she had other symptoms, too: intermittent stomach upset, headache, fatigue, trouble concentrating, and hair loss.

I watched the emotions play across her face as I laid out a plan for the various lab tests and consultations with a neurologist and a cardiologist that I felt would be necessary to obtain an accurate diagnosis. I also gave her a prescription for her upset stomach and a list of tasks she could do that might aid our search for the cause of her symptoms. With that she thanked me, and out the door she went. I hoped she would not be so overwhelmed that she would not return.

At that time, my days consisted of medical consultations based on sometimes hours of independent research. I loved my work as a diagnostician. Often patients would bring stacks of medical records to my office for a second opinion on what their regular doctor had suggested. From local referrals to ones from the Mayo Clinic, I saw many medical workups for a wide variety of complaints and conditions. I had reduced the time I spent at the office after giving birth to twin boys two years prior, but balancing work and home remained an evolving test of fortitude. Recently, I had been encountering a surprising number of patients with multiple complaints for which I could not find the cause.

Oftentimes in medicine, a cause cannot be found for a patient's discomfort. As new technologies are discovered that allow for diagnosis, and better dissemination of information is obtained with the Internet, recognition and cures can now be discovered for many conditions that went previously indeterminate.

Many of the patients for whom I could not find a diagnosis, including Toshiko, had entirely normal results on basic laboratory tests designed to identify the sources of many common problems—from thyroid conditions and menopause to anemia and inherited metabolic disorders. The gastroenterologist did say that a mild gastritis showed up on Toshiko's endoscopy, but, as expected, the cardiologist gave her a clean bill of health. The neurologist also found no cause of her fainting and other symptoms.

Looking at the results of tests I had ordered for a patient was like getting to see if I had solved a mystery, and it was something I really enjoyed. One thing that caught my eye in Toshiko's lab report, though, was the inclusion of results for a test I hadn't ordered: a measure of blood mercury level. And it showed an elevated level of mercury in Toshiko's blood.

The colleague who had ordered the test, a dermatologist named Kathy Fields, was no ordinary clinician. She was an avid researcher and had developed an acne treatment called Proactiv, for which she was frequently seen in television infomercials. When I called her, I jokingly asked what type of acne cream she was using to cause the mercury elevation in my patient. She laughed and quickly explained what had led to the test. She had been traveling in Idaho, she said, when a caller to a public radio station there complained of hair loss ostensibly caused by eating fish from a lake polluted with mercury. Curious, Dr. Fields wanted to test someone with abnormal hair loss herself, so when my patient appeared with that symptom and mentioned that she ate fish regularly, Dr. Fields added the test.

Neither Dr. Fields nor I had experience interpreting the result, so we had no idea whether Toshiko's elevated blood mercury level meant anything significant. Dr. Fields even wondered whether she had ordered the correct test.

I read the report that accompanied Toshiko's lab result carefully. Her whole-blood mercury level was 18.5 micrograms per liter (mcg/l), considerably above normal, defined by the lab as "less than 10.0 mcg/l at the end of a workweek." Fish can have mercury in it, I knew, and my patient consumed fish. But how did "end of a work week" enter in? I was not aware of any occupations that required a person to eat fish or mercury. I gave San Francisco Poison Control a call to sort all this out.

Poison Control was quite responsive to my questions at first. An intern referred me to a regular employee, who then consulted with her team. She called back to say that I needed to repeat the blood mercury test and collect a twenty-four-hour urine test concurrently. She wasn't sure why my patient had an elevated mercury level and suggested I ask the patient to allow her home to be evaluated. We discussed potential sources of exposure, which include mercury/silver dental amalgams (an amalgam being a mix of mercury with another metal), vaccines, herbs, homeopathic remedies, herbicides whose residues remained on fruits and vegetables, well water, cosmetics, and fish.

Mercury is a naturally occurring element, and is commonly seen in instruments such as thermometers and barometers. There are different types of mercury compounds, some of inorganic mercury, some organic mercury; unfortunately, Toshiko's blood test alone would not identify what type she was being exposed to. The several forms of mercury are cleared from the body differently and have different ranges of toxicities and symptoms of overexposure. Without the correct test, an accurate diagnosis may not be possible. Organic mercury, which has carbon atoms attached and is seen in food items, predominantly fish, is excreted in hair, feces, sweat, and breast milk but not to an appreciable degree through the kidneys. Nearly all mercury in fish is a form of organic mercury, methylmercury. Therefore, a blood or hair mercury test is more useful diagnostically in exposure from fish consumption than the routine urine heavy-metal screen used to detect the presence of inorganic mercury that most doctors are taught to order first.

Inorganic mercury has noncarbon atoms attached, and its presence in the environment can be increased by coal-fired power plants that emit mercury into the air and by chlor-alkali plants that dump mercury into the water. Mercury from these sources, whether from pollution or naturally occurring, is converted to methylmercury by bacteria in the soils and water. The bacteria are taken up by small organisms, which are themselves consumed by small crustaceans or fish, which are gobbled up by larger fish, and so on. These creatures do not rid themselves of mercury very well, so mercury becomes increasingly concentrated as you go up the food chain, a process known as bioaccumulation. Environmental scientists have been reporting for many years that high methylmercury exposure has an adverse impact on the development and fertility of many fish and other animals. Of the mercury compounds we humans are commonly exposed to, methylmercury is also deemed the most toxic. This is because it is readily absorbed by the body and has been known to enter every one of the body's cells, binding to tissue sulfhydryl molecules and interacting with other elements.

Within only a couple of days of Toshiko's visit, another new patient with puzzling symptoms came to see me. This time it was a woman in her early fifties, educated, responsive, and athletically svelte. As she took a seat in my consultation room, my office assistant happened to place the day's lab results on my in-box. I glanced down and saw Toshiko's retest results. The repeat blood mercury was essentially the same as the first time, while her urine test did not show an appreciable amount of mercury, indicating that she was being exposed to an organic mercury compound. Could it be the fish she ate? She ate at the finest restaurants and shopped at reputable grocery stores, and she said she did not consume any noncommercial fish while in the United States or Japan. Toshiko's was a puzzling case, as medical school training, when mercury was considered, mostly focused on occupational exposures that involved inhaling elemental or inorganic mercury, hence the laboratory report that defined mercury exposure by one's workweek. That was why physicians were often only taught to order a urine metal-screening test, which would be positive in such cases. I wondered if we physicians had been missing something. I put off thinking further about this and looked over to my new patient, eager to get started, and took my seat.

As soon as I greeted Amy, as I will call her, she declared in utter frustration that her house seemed to be making her sick. She went on to tell me of the waxing and waning nature of her symptoms—fatigue, headache, trouble concentrating, stomach upset, and even hair loss. It was like having a hangover, she said, only she did not drink alcohol. Sometimes she could not get out of bed for a couple of days. When she and her husband stayed at their house in France, she would feel better after a couple of months but would feel ill again within days of returning home to the United States.

She had seen numerous allopathic doctors, alternative care doctors, homeopaths, herbalists, and chiropractors. She had spent a small fortune on scans of her head and abdomen and had numerous tests performed on every body fluid imaginable. This certainly sounded like another I-don't-know-what-you-have case. Still thinking of Toshiko's latest lab report, I wondered to myself if Amy ate fish. I took a deep breath and got down to work.

Physicians have a standard protocol for obtaining information from their patients. We try to do our line of questioning the same way each time so as not to forget any question. We start with the chief complaint, or why the patient is there; followed by the history of the present illness; then past medical, surgical, and psychiatric history; allergies to medications; medications taken; family history; social history; and a review of symptoms for every organ in the body. I listened intently as Amy explained her symptoms in the initial history. When she seemed finished, I asked a simple question: "Do you eat fish?"

No one had asked about her diet before—ever—let alone a particular part of her diet. She looked at me strangely and said tentatively, "Yes." "How often?" She replied in a more stern voice, "I am a vegetarian, so I do not eat meat."

If I had learned anything taking care of people in San Francisco and the rest of the Bay Area, it was to tread carefully around a vegetarian's diet. So I dropped the subject until an appropriate time to ask again arose.

My medical school training was at the University of Illinois at Chicago, one of the first medical school programs to require doctors in training to take a nutrition class. Some students thought the class was a joke; food and nutrition had nothing to do with contracting noninfectious disease unless you were malnourished, they felt. In practice, I soon learned that malnourishment was easier accomplished than once thought, as many people even place themselves on "diets" of various colors—"I don't eat anything white" or "I only eat green." Early in my career one young woman came in with a stack of supplements and complained of not feeling well. She was a vegetarian, she said, but didn't eat vegetables—thus the supplements. What did she eat? "Lean Cuisine," she replied. Ever since, I routinely ask my patients about their diets.

I revisited the issue with Amy by asking her to tell me about the role of fish in her diet. She had been consuming fish at least nine times a week—tuna, swordfish, sushi, sea bass, halibut, and, as she put it, "you know, all kinds of fish." Little did she or I know then that her "variety" consisted of fish with the highest mercury content sold in the commercial market. Along with the other labs I ordered, I included a test for blood mercury level. Hers was 26.0 mcg/l, considerably higher than the 18.5 mcg/l found in Toshiko's blood. And the urine test? Mercury was not found.

Once I began to test patients for mercury's presence in instances where it seemed warranted, I soon found I had an increasing number with elevated levels on my hands. They had come to me for a variety of reasons, including nonspecific symptoms of headache, stomach upset, fatigue, insomnia, joint and muscle pain, hair loss, trouble concentrating, and the like. Some just came to establish me as their primary care physician and had no evident symptoms but were avid consumers of fish. The symptoms among individuals who had them could have come from a variety of sources—from viral illnesses to cancers—but I began finding that mercury seemed to be implicated in many instances. In my training, I remembered hearing from my professors that mercury can stay in the body "forever." Well, forever can be a very long time. Surely, my best internal medicine textbook would help me with my many questions. How long does it really stay in the body? Is long-term exposure harmful? And how can its level in the body be significantly reduced?

I began to search for information. My patients were being exposed to mercury through their fish consumption, it seemed. Since fish mercury is in the form of methylmercury, I first looked up methylmercury in the Cecil Textbook of Medicine, a standard general text most physicians would have on their shelf. There was only one paragraph devoted to methylmercury. The milder symptoms of methylmercury were said to be the same as for elemental mercury (commonly known as quicksilver, the type of mercury found in a thermometer): insomnia, nervousness, mild tremor, impaired judgment and coordination, decreased mental efficiency, emotional lability, headache, fatigue, loss of sex drive, and depression. There were also more severe symptoms listed: severe paresthesias (a prickling or tingling sensation of the skin), trouble speaking, trouble walking, tunnel vision, hearing loss, blindness, microcephaly (small brain size at birth), spasticity, paralysis, and coma. The "reference range"—what is considered the maximum acceptable to maintain good health—was less than 50 mcg/l for whole blood. No further information as to diagnosis, treatment, prognosis, and so forth was included in the textbook.

Perhaps it was just that my 1992 edition was out of date, so I looked on the Internet and came across a 1998 report to Congress about mercury written by the Environmental Protection Agency (EPA). I combed its volumes of pages extensively, hungry for information for my patients. The report recommended that the mercury level for humans be less than 5 mcg/l in order to avoid adverse health effects, especially with exposure over a lifetime—that was one-tenth what my medical text said was acceptable. Toshiko's level exceeded the EPA recommendation by a factor of more than three, and Amy's level was more than five times what was recommended. For me, a particularly fascinating part of the report was the comment that those who chose large predatory fish to eat could be at risk for significant mercury exposure. The EPA seemed to know that patients like Amy and Toshiko existed, but how could I make sense of the discrepancies between the two sources in order to advise my patients well?