- published: 30 Jul 2015
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Fish and shellfish concentrate mercury in their bodies, often in the form of methylmercury, a highly toxic organic compound of mercury. Fish products have been shown to contain varying amounts of heavy metals, particularly mercury and fat-soluble pollutants from water pollution. Species of fish that are long-lived and high on the food chain, such as marlin, tuna, shark, swordfish, king mackerel, tilefish, northern pike, and lake trout contain higher concentrations of mercury than others.
The presence of mercury in fish can be a health issue, particularly for women who are or may become pregnant, nursing mothers, and young children.
Mercury and methylmercury is present in only very small concentrations in seawater. However, it is absorbed, usually as methylmercury, by algae at the start of the food chain. This algae is then eaten by fish and other organisms higher in the food chain. Fish efficiently absorb methylmercury, but only very slowly excrete it. Methylmercury is not soluble and therefore is not apt to be excreted. Instead, it accumulates, primarily in the viscera although also in the muscle tissue. This results in the bioaccumulation of mercury, in a buildup in the adipose tissue of successive trophic levels: zooplankton, small nekton, larger fish etc. The older such fish become, the more mercury they may have absorbed. Anything which eats these fish within the food chain also consumes the higher level of mercury the fish have accumulated. This process explains why predatory fish such as swordfish and sharks or birds like osprey and eagles have higher concentrations of mercury in their tissue than could be accounted for by direct exposure alone. Species on the food chain can amass body concentrations of mercury up to ten times higher than the species they consume. This process is called biomagnification. For example, herring contains mercury levels at about 0.01 ppm while shark contains mercury levels greater than 1 ppm.
Amber Evangeline Valletta (born February 9, 1974) is an American actress and model. She began her career as a model for fashion agencies, and appeared on cover pages of internationally recognized magazines. She made her film debut in Drop Back Ten (2000). She then starred in the hit film Hitch (2005). She has since appeared in films such as Man About Town (2006), Dead Silence (2007), Gamer (2009), and The Spy Next Door (2010). She's also known for role as Lydia Davis on the ABC television drama series Revenge.
Valletta was born in Phoenix, Arizona and raised in Tulsa, Oklahoma. Her mother worked at the post office. She attended Booker T. Washington High School. She got her start in the fashion industry when her mother enrolled her in modeling school at the age of fifteen at the Linda Layman Agency. She appeared on the cover of magazines and in advertisements for Louis Vuitton, Calvin Klein and Versace and hosted MTV's House of Style with fellow model Shalom Harlow.
She was presented on the November 1999 Millennium cover of American Vogue as one of the "Modern Muses". Valletta's first role was in the comedy film Drop Back Ten (2000); Later that year, she played a supporting role in the thriller film What Lies Beneath. The film was directed by Robert Zemeckis and starring Harrison Ford and Michelle Pfeiffer. She appeared alongside Nicolas Cage in The Family Man. In 2003, she played as Celine in Danny DeVito's Duplex, starring Ben Stiller and Drew Barrymore, she also played as Meline in Raising Helen (2004), opposite Kate Hudson, Hayden Panettiere, Abigail Breslin, and Helen Mirren.