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It doesn’t tell us there’s a hazard [if one has mercury levels above EPA’s RfD].Chicago Tribune: But the FDA warning did not reflect the EPA's science on what constitutes acceptable exposure to mercury. Based on the FDA's own testing, many consumers following the agency's advisory still could absorb too much of the toxic metal. For example, if a 161-pound woman--the average weight of U.S. females of childbearing age--ate 12 ounces of lobster in a week, she would expose herself, on average, to twice as much mercury as what the EPA considered acceptable. If she ate 12 ounces of orange roughy, or about two meals, she would be three times over the limit. (December 12, 2005) Response: More RfD confusion
The Tribune monotonously repeats confused claims of being “over EPA’s limit,” suggesting a lack of understanding of EPA’s own definition of an RfD.  Further assessing EPA’s RfD as overly restrictive (see Sec. 2), we offer additional considerations. First, it is clear from the ethical guidelines established by the Institutional Review Board of the National Center for Health Statistics of the CDC (the governing body which approved the recent National Health and Nutrition Examination Survey –NHANES -- mercury survey for U.S. women and children) that caution notices must be issued to NHANES participants only if their total hair mercury levels exceed 15 ppm or total blood mercury exceeds 200 ppb (see McDowell et al., 2004). By contrast, EPA considers hair levels “safe” only below 1 ppm, and blood levels “safe” only below 5.8 ppb. Secondly, consider informal survey results (funded by the Heinz Endowment) of hair mercury levels for 260 members of the Society of Environmental Journalist (SEJ) attending a December 2004 meeting in Pittsburgh (Fig. 14-A). Up to 27% (n = 70) of attendees tested hair mercury levels above what is considered “safe” by EPA. Applying these levels to CT’s standard for harm, is one then justified in assuming a large portion of environmental journalists may be neurologically impaired, or is EPA’s MeHg RfD simply overly conservative and misapplied by alarmists?  In response to the findings, the coordinator for the SEJ survey, Professor John Spengler of the Harvard School of Public Health, appeared to answer the question. Upon discovering his hair mercury level to be 3.4 ppm -- more than 3 times the EPA limit! Spengler appropriately reasoned:“But I’m not going [to be] apoplectic about it because I know if I just watch my consumption, I can moderate that over time...and there’s that safety margin [i.e., a factor of 10]...that I suspect I’d have to be much higher for much longer to really have symptoms” [i.e., at least 58 ppb daily, for a lifetime]. [Emphasis and comments added] In other words, Spengler does not strictly interpret EPA’s RfD as a bright line above which is unsafe. Eat more fish! A third consideration relates to real concerns for potential public harm flowing from a cresting tide of alarmism and misinformation.  The average American needs more, not less, fish nutrition -- despite an encouraging trend of recently increased per capita fish consumption in the U.S (Fig. 12-A). Fig. 14-B and Fig. 14-C suggest elevated U.S. susceptibility to potentially life-threatening diseases due to current dietary deficiencies for EPA+DHA omega-3 polyunsaturated fatty acids. U.S. consumption is already 3 to 6 times lower than recommendations by the National Institutes of Health (NIH) and the American Heart Association (AHA). American children and adults are likely void of the health benefits proffered by omega-3 fatty acids, compared to people from the high fish-consumption nations like Japan, Singapore, Hong Kong and Scandinavia. This is why fear-based restriction or avoidance of fish intake will likely spawn increasing, negative public health consequences (See Sec. 1). Even the recent trend for shrimp overtaking canned tuna as the top seafood consumed per capita in the U.S. may not be an entirely positive outcome (Fig. 14-D). Shrimp has, on average, a lower content of total omega-3 DHA + EPA fatty acids than does canned tuna species (0.33 to 0.44 grams per 100 grams consumed versus 1.48 to 1.6 grams, respectively ).  Amazonia
Lastly, Dorea et al. (2004) report that: There is evidence of fishing villages in the Amazon dating back eight millennia. In Brazilian times, there are no cases of required medical attention due to [mercury] health problems cause by fish consumption. Regarding neurobehavioral changes, the special fishing skills of some Amazonian native people do not suggest the existence of a compromising problem. Some Amazonian tribes fish with bow and arrow in turbid waters where they have to remain still for hours, apparently demonstrating good peripheral vision and outstanding motor coordination. [Emphasis added] Dorea further reports that these Amazonian populations experience chronic MeHg exposures, through large daily intake of fish, far exceeding any level likely ever experienced by Chicago residents or other Americans. For example, in the Rio Tapajos gold-mining region, researchers detected hair levels reached 13.8 ppm and 21 ppm, with one value reaching 303 ppm! Riparian populations of the Rio Maderia region showed a prevalence of 3% with hair Hg above 50 ppm. And there has never been reported poisonings or Minamata-like illness among these peoples. By comparison, EPA’s RfD is only about 1.0 ppm. Conclusion
“The health implications of any diet are determined by the balance between essential nutrients and toxic substances that are naturally present in the food consumed.” Misunderstanding and misapplication of EPA’s restrictive and controversial mercury RfD for fish consumption leads to diminished public health. Failure to properly discern risks may prove fatal. |
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