My Life as a Guinea Pig
It seems so obvious: the chemicals around us contribute to ailments like asthma, declining fertility, and certain cancers. Yet with a few notable exceptions -- such as mesothelioma, a rare cancer of the chest wall caused by asbestos -- it has been nearly impossible to link a particular human disease to a particular toxin. Time and again, epidemiologists fail to find culprits for cancer clusters. There are just too many confounding variables, and sample sizes are often too small.
Still, scientists in environmental health achieve discoveries all the time. Thanks to new microdetection tests and to fruitful cross-pollination with genomics, molecular biology, and endocrinology, the field seems poised on the brink of revelation. A recent study in Environmental Health Perspectives reports that among factory workers exposed to PCBs between the 1930s and 1970s, nonwhite women were more likely than white women to contract breast cancer. Previous studies, focused primarily on white women, had found no link between breast cancer and the chemicals.
Armed with an improved understanding of genetics, scientists are gaining insight into why some individuals and groups of individuals are more susceptible to environmental illnesses than others. Why do some people contract lung cancer after years of smoking while others do not? What if you could take a genetic test before lighting up to see which camp you fall into? As David Ewing Duncan asks in Experimental Man: "Have I been born with the best genetic and physiological armor that evolution can provide?"
To attempt to answer this question, and to explore the newfangled world of environmental genomics, Duncan turns himself into a guinea pig. The data he provides at the beginning of Experimental Man nicely sum up his epic medical project.
- Amount of blood drawn for testing: 1.4 liters (or one-quarter of his average blood volume)
- Number of chemical toxins his blood was tested for: 320
- Number found: 165
- Number of genetic markers tested: 7,000+
- Approximate cost of testing: as much as $500,000 (many tests were performed for free)
It's a brilliant idea for a book: to learn as much as possible about his own body's chemical burden as well as his genetic fortitude, and then to fit the two sciences together as best he can. Experimental Man is Rachel Carson meets Survivor, a kind of reality-TV voyeurism into one man's body. If it sounds like the ultimate narcissistic exercise, it is. Duncan calls himself an "early genetic adopter-exhibitionist." We learn about everything from his cognitive speed to his ability to metabolize caffeine. For the most part, his approach works to personalize these emerging fields. He sheds an essential and fascinating light on our chemical-filled world and how it may affect us and our progeny. "Manufactured compounds we use in everyday products do not appear in nature and have entered our environment so recently," he writes, "that our genes, cells, brains, and bodies have not yet evolved specific mechanisms for coping with them."
Learning about all the foreign substances in one's body can get a bit creepy, but that's the point. After Duncan consumes two meals of fish in one day, the methylmercury in his blood leaps from 4 micrograms to 14 micrograms per liter, more than double the Environmental Protection Agency's recommended level of 5.8. (His doctors chastise him for such experimental foolishness and tell him never to do it again.) Here Duncan's solipsism gets in the way of his larger mandate: he doesn't speculate more broadly, nor does he report exposure levels in the wider population. How unusual is it to eat fish twice in one day? Duncan acknowledges that he would worry more if he were a pregnant woman. He doesn't mention the Inuit, who subsist largely on a marine diet and are reported to have the most polluted blood on earth.
Duncan is startled to learn that his blood's load of certain flame retardants is 12 times above the national average. He can only speculate why. Extensive travel in doused jetliners? A diet heavy in meat, in which these chemicals might accumulate? And what might it mean for his health? Nobody has a clue, which enables Duncan to underscore how little scientists know and how vulnerable the rest of us feel.
He ably explains what scientists do know, and it's enough to make a reader squirm. For example, PCBs appear to reduce the expression of the BRCA1 gene, which otherwise helps suppress breast-cancer tumors. Mercury and other metals can deactivate genes involved in blood clotting. Although the science is still crude, Duncan writes, it's clear that chemicals can affect "the delicate and dynamic balance of forces inside our bodies."
This is tantalizing material; I only wish Experimental Man pushed it further. Regrettably, Duncan loses sight of his mandate and instead tries to encompass the broad sweep of personalized medicine. In the second half of the book, he abandons his environmental inquiries to try out seemingly every faddish medical test under the sun. But for the author, a very healthy 50-year-old, little is at stake.
Duncan undergoes a full-body CT scan, which reveals nothing but a creaky knee from an old surfing accident and a benign cyst on his kidney. He sleeps hooked up to a prototype invention called the iBrain, a single electrode wired to his forehead to monitor his sleep cycles. He spends 22 hours playing gambling games in MRI machines to see how he responds to risk. He takes an online exam that concludes, "You correctly identified 24 tunes (out of 26) on the Distorted Tunes Test. Congratulations! You have a fine sense of pitch." He puts a piece of paper in his mouth to reveal that he is among the 25 percent of us who cannot detect bitter tastes.