selenium. Seafood also is a primary source of the omega-3 fatty acids EPA and DHA. The evidence detailed in Chapter 3 indicates that consumption of seafood and/or EPA/DHA by pregnant females may provide benefits to their developing fetuses. Infants receiving EPA/DHA either from breast milk or supplemented formula may benefit in terms of neurological and visual development. Similarly, there is evidence that consumption of fish is associated with cardiovascular benefits in the general population.
These benefits must be balanced against risks to health, as reviewed in Chapter 4, from exposure to chemical and/or microbial contamination that may be present in some seafood available to US consumers. The bestcharacterized risk from chemical contamination of seafood is from methylmercury, a potent neurotoxin. Thus, the population groups at greatest risk from exposure to contaminants in seafood are the developing fetus, infants, and young children. As discussed in Chapter 4, a Reference Dose (RfD) has been established for methylmercury on the basis of developmental tests in children born to mothers from populations where seafood is a major part of their diets. At the same time, evidence suggests the fetus and infant may be among the principal beneficiaries from certain nutrients in seafood. Evidence available on levels of MeHg that may be detrimental to nonpregnant adults has not allowed the formulation of a similar reference dose based on risks to these population segments.
In establishing their joint advisory targeted at pregnant women and children, the US Environmental Protection Agency (US EPA) and Food and Drug Administration (FDA) examined potential intakes of MeHg that would occur in pregnant women given consumption patterns using various available commercial sources of seafood. If predatory fish high in mercury were avoided completely, they concluded that up to 12 ounces of fish (four 3-ounce servings per week) could be consumed without exceeding the RfD dose that has been established with studies in populations of women consuming substantial amounts of seafood (US EPA/FDA, 2004) (see Chapter 4). Though the committee recognized that the RfD was not a “bright line” that established a firm cutoff for risk, the FDA/EPA fish advisory provides reasonable guidelines for pregnant women to consume seafood in amounts that may confer benefit without significantly increasing risk. There is little evidence available about levels of methylmercury that may be detrimental to other segments of the population.
Risks from other contaminants in seafood are, comparatively, less well-characterized than methylmercury. Contamination from persistant organic pollutants (POPs) has been characterized at exposure levels that result from industrial releases or occupational exposure, and for fish-consumers in geographic areas where contaminants are more concentrated. However, at lower levels of exposure there is less information available on adverse health effects. In addition, levels of dioxin-like compounds (DLCs) and polychlori-