Mercury Contamination in Fish - Research Paper Example

? Mercury Contamination in Fish Mercury Contamination in Fish Objective The objective of the project is to highlight the impact of aselected substance on the environment. In this regard, the paper specifically examines health effects of mercury from dietary fish. The paper narrows down to two regions; the U.S.A (New Hampshire) and Bangladesh. The paper illustrates how mercury in fish poses significant environmental hazards in the U.S and Bangladesh. The paper compares how these two countries are affected by this environmental challenge. The paper is based on two studies carried out in Bangladesh and the U.S. In the first study, Rees et al. (2007) aimed at elucidating how toenail mercury is related to dietary fish consumption in New Hampshire. In the second study (Bangladesh study), Shamshad, Shahidur, and Tasrena, (2009) focused on determining the level of trace elements (including mercury) in fish feed and shrimp sampled from aquaculture ponds. Mercury is an established heavy metal, environmental pollutant with deleterious health effects in human beings (Eisler, 2006). Mercury toxins lead to neurological impairment in humans (National Research Council, 1978). Mercury in contaminated fish food consumed by pregnant women may affect the unborn baby’s brain and nervous system. Children who were affected by mercury while in the womb have poor cognitive thinking and memory and reduced concentration (Health Effects, 2012). Studies have proved that adults, children and developing fetuses are in danger of mercury intoxication (National Research Council, 1978). Schmitt, Stricker and Brumbaugh (2011, p. 1) argue that methyl mercury concentrations in some U.S species of fish (Micropterus dolomieu and Hypentelium nigricans) “are significantly high to represent a threat to human health and wildlife”. The U.S has a high risk of suffering from mercury intoxication consumed from fish compared to Bangladesh, in spite of Bangladesh having more fish than the U.S. Studies on mercury intoxication are essential because they enable stake holders to devise preventative measures. Thus, this paper examines the effect of mercury toxins in fish in Bangladesh and the U.S. The graph below is an example showing comparing levels of mercury in blood lead and the risk for autism in children. The graph indicates a significant correlation between the two variables. Figure 1: Graph indicating the distribution of Hg levels in ‘charge children’, comparing four groups: regressive autism, autism of early onset, general population controls and developmentally delayed children. Source: http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.highlight/abstract/1773/report/F Materials and Methods The Bangladesh study assessed the level of trace elements content in fish feed and shrimp sampled from aquaculture ponds in Bangladesh by the use of Flame Atomic Absorption Spectrometer (FAAS), Cold Vapor Absorption Spectrometer (CV-AAS), and Hydride Generation Atomic Absorption Spectrometer (HG-AAS). The study was based on the theoretical assumption that since tannery and poultry waste are used as fish feed in Bangladesh, there is an accumulation of toxic contaminants in cultured fish posing food safety risk. Toxic metals including mercury are used in the manufacture of tanneries, dye production, textile dying and paper and pulp mills. Two samples of Shrimp and twelve samples of the feed were collected from different aquaculture sites in Bangladesh. The sample was washed by de-ionized water and then air-dried. They were then analyzed using FAAS, CV-AAS and HG-AAS (Shamshad, Shahidur, & Tasrena, 2009). The American study was conducted as follows: method one; participants observed a 3 day diary of water and seafood consumption which facilitated the calculation of the average consumption of finfish and shell fish on a weekly basis. Method two; the average weekly consumption of fish (shell fish, tuna and dark fish) was estimated using semi quantitative food frequency questionnaire. Method three; the weekly consumption of each fish species was determined by the use of detailed questionnaires. Results Mercury was found to be 0.03kg/mg in shrimp feed and in shrimp samples. These levels are below EU permissible limit Hg set at 0.1mg/kg (Shamshad, Shahidur, & Tasrena, 2009). In the other study, the results indicated that there was a significant correlation between toenail mercury levels and various measures of fish consumption derived from the semi quarantine food frequency questionnaire (Rees et al., 2007). No correlation was found between the consumption of fish and years of education (r=0.13, P=0.53). In addition, Omega-3 fatty acid consumption had a significant correlation with toenail mercury concentration (r=0.46, P=0.016) (Rees et al, 2007). Discussion Mercury tends to occur naturally in marine food chain as organically bound Hg (methyl mercury) or inorganically bound Hg. The organic form is the most harmful. The levels of Hg recorded in shrimp food and samples from the Bangladesh study are below EU set permissible levels. In the American study, multivariate studies indicated that toenail mercury concentration dependent significantly on finfish and shellfish consumption. Toenails have proved to be essential biomarkers of exposure to trace elements including mercury. Studies have proved reproducibility of toenail mercury levels overtime, and correlation of toenail mercury with dietary intake of fish have both been demonstrated (Rees et al., 2007). Toenail mercury concentration reflects both methyl mercury and elemental mercury. However, there are no set standards as of now for comparing toenail mercury concentrations or dietary assessments. In addition, other sources of mercury in the environment may also contribute to mercury content in the body of an individual. Mercury poses food a safety risk through dietary fish consumption. Mercury disrupts the nervous system of affected individuals. Fish is a source of food to a significant number of citizens in different countries. Thus, measures should be formulated to avoid contamination of aquatic lives (especially fish), with mercury. The United States needs to adopt safer sources of fish food like those used in Bangladesh. Conclusion The results from the Bangladesh study indicated that the consumption of shrimp which are produced in aquaculture farms does not constitute a food security concern in respect to mercury, Arsenic and Cadmium and Lead. On the other hand, results from the U.S study proved that toenail mercury concentration can be used as a biomarker for mercury exposure through dietary fish consumption. Well defined procedures for the measurement of mercury toxins as a food safety risk should be established. References Eisler, R. (2006). Mercury Hazards to Living Organisms. London: Tailor & Francis. Graph retrieved on 24 March 2012 from http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.highlight/abstract/1773/ report/F Health Effects. (2012). Retrieved on 24 March 2012 from http://www.epa.gov/hg/effects.htm. National Research Council (U.S). (1978). An Assessment of Mercury in the Enivironment. Wahington D.C: National Academies. Rees, R. et al. (2007). Toenail Mercury and Dietary Fish Consumption. Journal of Exposure Sience and Environmental Epidiemology, 17, 25-30. Schmitt, C., Stricker, C and . Brumbaugh, W. (2011). Mercury Bioaccumulation and Biomagnification in Ozark Stream Ecosystems. PubMed.gov, 74(8), 2215-24. Retrieved on 21 March fromhttp://www.ncbi.nlm.nih.gov/pubmed/21868094. Shamshad, B., Shahidur, R and Tasrena, R. (2009). Studies on Toxic Elements Accumulation in Shrimp form the Fish Feed used in Bangladesh. Asian Journal of Food and Agro- Industry, 20(04), 440-444. Read More