Professor Bruce McDuffie: Discovered Mercury in Seafood

Enlarge Image Image Gallery PROFESSOR BRUCE MCDUFFIE PHOTO BY JOHN G. MCDUFFIE

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In the late fall of 1970, Bruce McDuffie—a chemistry professor at the State Universityof New York at Binghamton threw a large flap into the fishing industry with his discovery of .75 parts per million of mercury in cansof tuna taken from supermarket shelves. This level of mercury—an element that can cause blindness, crippling and death when eaten ill minute quantities —exceeds, by 50%, the limits supposedly allowed by the Food and Drug Administration and— quite naturally—made headlines all over the world.

Professor McDuffie's announcement, shortly thereafter, of finding even higher concentrationsof mercury in swordfish rattled the FDA, the public and the fishing fleet even further and the two reports—confirmed by the FDA—caused the withdrawal of hundreds ofthousands of dollars of tuna and swordfish from the market.

High levels of mercury have since been found in many other seafoods—both fresh and salt water—and the problem promises to be with us for years. Hal Smith recently asked Professor McDuffie to comment on his findings, the dangers of eating tuna and the future of the fishing industry.

PLOWBOY: Why is mercury pollution dangerous?

MCDUFFIE: Mercury is a toxic element not known to be necessary for life. In fact, it can be lethal. Mercury has long been used in scientific experiments to kill bacteria, interfere with certain types of enzymes and that sort of thing. It can be a very toxic substance in the body.

PLOWBOY: Short of causing death, what damage can it do?

MCDUFFIE: Well that depends on the type of mercury. There are several different forms of mercury in the environment. One is the element itself: the vapor from the metal. This vapor can be inhaled and absorbed and then it does about the same as inorganic mercury, mercury salts.

There are also organic forms of the element. One type that has been used a lot as a fungicide is phenyl mercury. The body absorbs this organic form of mercury pretty completely . . . but once in the body it acts more like inorganic mercury methylmercury—the most dangerous form.

Methylmercury is formed in lake bottoms and has been used to treat seeds. Once it gets into food, this substance is almost completely absorbed by the body. Once absorbed, methylmercury has the ability to penetrate the central nervous system, the brain. It tends to be more concentrated in the brain than other parts of the body and it tends to do irreversible damage. So the most dangerous form of mercury pollution for man is methylmercury.

Unfortunately, inorganic mercury may be changing to methylmercury in the aquatic environment. Certainly the mercury in tuna and swordfish is predominantly — if not 100% — methylmercury so we are dealing, in the food we eat, with the most hazardous form.

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