following points illustrate the variables that influence what can be generally applicable:

  • Concentrations of contaminants in seafood are known to be influenced by factors such as location of harvest, seasonal variations, size, and species. General guidance to consumers must be based on available data for average levels of potential contaminants in type or species of seafood. Sparse data on adverse health effects associated with some contaminants make it difficult to estimate the variability of specific contaminant levels in seafood, as well as levels of EPA and DHA.

  • Levels of EPA and DHA in seafood depend upon the fatty acid content of the type of seafood consumed, the source of fat in feed for farmed fish, and serving size. Sparse data make it difficult to determine variability in the EPA and DHA content. As more seafood is produced by aquaculture rather than wild-caught, EPA and DHA levels within species could change.

  • There is considerable uncertainty about the concentration of contaminants that present a health risk. Methylmercury exposure levels that pose a risk were established for the most vulnerable members of the population, i.e., the fetus, infant, and young child. However, methylmercury exposure levels that pose a risk for adverse health effects for other population categories listed above are unknown. Similarly, exposure limitations for persistant organic pollutants, dioxins and dioxin-like compounds, and PCBs are unclear.

  • Methylmercury intake exposures that are used to indicate a potential for risk for the fetus, infant, and young child are adjusted (as noted in Chapter 4) to make them more conservative than levels of observed risk.

These uncertainties mean that guidance to individual consumers can, at best, present the broad trade-offs of benefits and risks associated with seafood selections and consumption patterns, and inform consumers of the inherent uncertainties therein. The committee is aware that considerations other than health benefits or risks also may influence consumers’ choice of seafood. These include environmental concerns about aquaculture and the sustainability of wild seafood stocks. These considerations are beyond the charge to the committee and are not included in the decision pathway.


  1. Relatively few studies have attempted to simultaneously assess both the health benefits and the risks associated with seafood consumption. However, there is emerging evidence of the trade-offs between the benefits

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