|See this related seafood lobby fable:|
|Fable: Mercury risks are merely “hypothetical”|
Fish consumption is essentially the only source of exposure to methylmercury. As more Americans eat more fish, mercury exposure is likely to increase. Federal and State public health and environmental officials consider mercury exposure from fish consumption to be a significant public health problem requiring effective risk-management measures.
Sport anglers who catch and eat fish from locally contaminated waters are one concern, and many states and the US Environmental Protection Agency (EPA) have issued public advisories to warn fishermen about mercury in fish caught at specific locations.
Mercury exposure from commercially-caught seafood is also a public-health concern. In a national survey carried out by the Centers for Disease Control in 1999-2004, 6 percent of women of childbearing age had blood mercury levels above the EPA’s definition of a safe level (the “Reference Level”). Blood mercury levels above that reference point do not guarantee that harm is occurring, but they do show an increased risk of adverse effects on the developing brain. With some 4 million births per year in the US, this means at least 240,000 babies per year are exposed to mercury doses before birth that pose a greater-than-acceptable risk of adverse effects. A risk that affects such a large population group is a substantial public health concern.
Babies are not the only people who may be harmed by mercury. People who eat much greater than average amounts of fish, and who repeatedly choose fish varieties with above-average mercury levels, sometimes develop clinical symptoms of methylmercury poisoning. There are far fewer people in this category than there are women of childbearing age, but their unusually high mercury exposure and associated risk of toxic effects is also a public health concern.
Fable: Mercury risks are “hypothetical.”
Facts: Unlike some toxic substances whose hazards are known only from tests done on animals, the hazards of methylmercury have well been documented in studies of human populations exposed to mercury in their diets, from eating fish (and sometimes also whale meat). We know for a fact that mercury causes health damage in people who are exposed to too much of it. What is known with less certainty is how much mercury is “too much.” (See “Safe Doses”)
The scientific evidence that establishes the reality of risk from methylmercury in fish, described in summary form above, has been reviewed repeatedly by authoritative bodies such as the National Research Council/Institute of Medicine of the National Academy of Sciences, and the World Health Organization of the United Nations. There is no doubt at all that mercury risk is real. The questions that require closer analysis are, how large is the risk, and who is at risk? Both are discussed elsewhere on this site.