Explain+Contaminants+In+Fish

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Explain Contaminants In Fish

Top Contaminants

There are a couple contaminants in particular that end up in fish. The EPA issues warnings on these contaminants if they find large quantities in the fish. The top five contaminants include Dioxins, DDT, Chlordane, Polychlorinated Biphenyl, and Mercury.

Dioxin: Dioxins are some of the most toxic chemicals in science. This is a major bio-accumulator the does not leave the body. Dioxins can be found in kinds of foods including beef, dairy, milk, chicken, pork, and fish. They are found in small amounts but they bio-accumulate and can stay in the body for a lifetime. Because of this, after a lifetime the Dioxins can become very toxic. Dioxins are heterocyclic, organic, anti-aromatic compounds. The chemical formula for Dioxins is C4H4O2. PIXE would not be able to detect a Dioxin alone because the smallest atom that PIXE can detect is Aluminum. It would not be able to detect the carbon, the hydrogen, or the oxygen. Dioxins typically bond with chlorine though. PIXE can detect chlorine because it is larger than aluminum. If I was to detect chlorine in the fish with PIXE I would have to find another method to differentiate where the chlorine comes from.



DDT: DDT stands for **d**ichloro**d**iphenyl**t**richloroethane. This is a synthetic chemical that was used heavily in the 1940's as an insecticide. It was used to control mosquitoes from spreading malaria and lice form transmitting typhus during world war II. It worked well as an insecticide but neither the environmental effects nor the health effects were know when it was used. Now it is known to be extremely toxic and cancer causing. The chemical formula for DDT is C14H9CL5. This is a similar situation to the Dioxins where I will be able to detect the chlorine with PXE but I will not specifically know that it is from DDT. If I see chlorine I will know there is something there. I should be able to find another method to find out what chemical is in the fish.



Chlordane: The chemical formula for chlordane is C10H6Cl8. It is an organochlorine compound that has been used as a pesticide. It was used as an insecticide until 1983 when the United States Environmental Protection Agency (EPA) banned all uses except for termite control. Then 5 years later the EPA officially banned all uses of chlordanes. It bio-accumulates in animals and fish. Chlordane has been linked with causing certain types of cancer.



Polychlorinated Biphenyl: Polychlorinated Biphenyls are typically refered to as PCBs. A biphenyl is a molecule composed of two benzene rings. It becomes polychlorinated when 1 to 10 chlorine atoms attach to the biphenyl. The general chemical formula for PCBs is C12H10-xClx, where x is the 1 to 10 chlorine atoms. PCB's have been banned by the United States Congress since 1976. PCB's are very common polutants in the United States.



Mercury: Mercury is a pure element. Its symbol on the periodic table is Hg. Mercury is a heavy, silvery, liquid metal. Mercury has many uses including fluorescent lamps and mercury vapor lamps, but it is a very toxic element. Fish and shellfish have a natural tendency to concentrate mercury in their bodies. Its most often in the form of methylmercury, a highly toxic organic compound of mercury. The chemical formula for methylmercury is CH3Hg. The EPA is responsible for regulating and managing mercury contamination. They also are in charge of issuing advisories.



Two key biological terms to know in relation to these contaminants are biomagnification and bioaccumulation. Biomaginification means that the substance concentration magnifies within the organism due to the substance being slow to break down and having a low or nonexistent rate of internal degradation or excretion of the substance. This is often due to water insolubility. Bioaccumulation occurs within the trophic level of fish. It is the increase in concentration of a substance in an organism due to absorption from food and the environment.

References:

[] @http://en.wikipedia.org/wiki/Dioxin_(chemical) [] [] [] [] @http://en.wikipedia.org/wiki/Methylmercury @http://toxics.usgs.gov/definitions/methylmercury.html http://en.wikipedia.org/wiki/Mercury_(element) @http://en.wikipedia.org/wiki/Biomagnification @http://en.wikipedia.org/wiki/Bioaccumulation