Introduction
Persistent organic pollutants (POPs) categorize a vast assemblage of environmentally toxic compounds and have received notoriety in recent decades for their lingering presence within an ecosystem. Most POPs are lipophilic and enabling them to bioaccumulate within an ecosystem which may potentially cause long lasting damage as they are transferred through consumption of an organism’s fat content (Ritter et al. 1995). The chemical stability of POPs allows these substances to persist in an ecosystem for many years either in soils or within animal tissue (Ritter et al. 1995). The recent detection of POPs in Arctic regions has raised concern over the severity these toxins may pose to Northern ecosystems (Letcher et al. 2010). Monitoring the amount and rate that POPs are being leeched back into the North is crucial in understanding the extent of ecosystem damage as well as identifying areas of further research. Schmid et al. (2011) found that glacial fed lakes contain higher POP levels compared to non-glacial fed ones demonstrating the potential for reintroduction of these pollutants back into the ecosystem. Another study by Blais et al. (2001) produced similar results as they detected higher levels of POPs in glacial streams compared to water from valley streams and precipitation. Blais et al. also believes free suspending POPs in glacial water are more prevalent because of the low organic material in these waters; consequently enabling them to travel further before being caught by soil or organic material.
The POPs in focus for this study are chlordane, dichlorodiphenyltrichloroethane (DDT), and polychlorinated biphenyls (PCBs). Chlordane, DDT, and PCBs have all been widely banned or reduced globally since the later qua...
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The premise of Theo Colborns’ research was to find the connection between the rising incidences of cancer and environmental contamination in the Great Lakes region. However, during field and laboratory studies, Colborn discovered that there was no direct link between the contamination and cancer. However, Colborn did find reoccurring patterns of abnormal behavior and deformed offspring amongst the wildlife populations in the Great Lakes region. Elevated levels of polychlorinated biphenls (PCBs), pesticides dieldrin, DDT, lindane and chlordane were found during tissue analysis of the wildlife in the Great Lakes region (Colborn et. Al 1996). These elevated levels were found in offspring of the wildlife who appeared to be healthy. This supported Colborns’ hypothesis that these contaminations disrupt hormones produced by the endocrine system during growth and development, which will then cause physical and behavioral abnormalities in the fetus.
There are many ways pollutants can enter lakes and rivers: agricultural and urban runoff, industrial outfalls, migration through groundwater, through the food chain, and many more. Many p...
The endocrine system of animals is a main source of bioregulatory compounds. Hormonal actions regulate all aspects of animal life: reproduction and development, digestion, metabolism, behavioural responses etc. (Hertenstein 2006, Norris 2007). Hormones and glands of vertebrate and invertebrate endocrine system differ in structure and function, but their main regulatory role remains conserved. However, the balance among the environmental clues, hormonal signals and organisms’ responses can be easily disturbed. One of the causes of this disturbance is the presence of Endocrine Disrupting Chemicals (EDC’s) in the environment.
The major source of mercury is the natural degassing of the earth's crust, including land areas, rivers, and the ocean, and this source is estimated to produce on the order of 2700 to 6000 tons per year. The total man made release into the atmosphere is about 2000 to 3000 tons, and it is difficult to assess what quantities of mercury come from human activities and what quantities from natural resources. Run-off into natural bodies of water may contain mercury from both anthropogenic and natural sources, so it is difficult to assess how much released into the atmosphere is from man made or natural sources. Nevertheless, mining, smelting, and industrial discharge have been factors in the environmental contamination in the past. For instance, it is estimated that loss in water effluent from chloralkali plants, one of the largest users of mercury, has been reduced to 99% in recent years. Industrial activities not directly employing mercury or mercury products give rise to substantial quantities of this metal. Fossil fuel may contain as much as 1 ppm of mercury, and it is estimated that about 5000 tons of mercury per year may be emitted from burning coal, natural gas, and from the refining of petroleum products. Calculations based on the mercury content of the Greenland ice cap show an increase from the year 1900 to the present and suggest that the increment is related both to an increase in background levels of mercury in rainwater and to man made r...
Evidence provided to support these claims of human and wildlife harm is largely from laboratory studies in which large doses are fed to test animals, usually rats or mice, and field studies of wildlife species that have been exposed to the chemicals mentioned above. In laboratory studies, high doses are required to give weak hormone activity. These doses are not likely to be encountered in the environment. However the process of bioaccumulation can result in top-level predators such as humans to have contaminants at levels many million times greater than the environmental background levels (Guilette 1994). In field studies, toxicity caused by endocrine disruption has been associated with the presence of certain pollutants. Findings from such studies include: reproductive disruption in starfish due to PCBs, bird eggshell thinning due to DDT, reproductive failure in mink, small penises in alligators due to DDT and dicofol (Guillette 1994, Colburn et al 1996). In addition, a variety of reproductive problems in many other species are claimed to be associated with environmental contamination although the specific causative agents have not been determined. One recent discovery that complicates the situation is that there are many naturally occurring "phytoestrogens", or chemicals of plant origin that exhibit weak estrogenic properties.
Chemical pollution into the environment can cause both genotypic and phenotypic changes in many organisms, including humans. More specifically, environmental pollutants like BPA can act as xenoestrogens (estrogen imitators), ultimately affecting hormonal activity and production in an organism. This alteration in activity and production can be termed as endocrine disruption. The endocrine system regulates a variety of processes responsible for growth and development, including gonadal formation and function, digestion, metabolism, sex differentiation, and embryonic development (reviewed by Flint et al., 2012). Chemicals that interfere with the function or structure of the endocrine system can be defined as endocrine disrupting compounds (EDCs) (US Environmental Protection Agency, 2007).
One of the many examples of endocrine disruptors are the effects pesticides on amphibians and alligators. These model organisms have been observed to have an increased exposure
The continued use of this pesticide requires research into the influence of DDT and other persistent chemicals on the environment and the human population. The pesticide enters the environment by run-off from soil, volatilization and its byproducts (DDD and DDE) enter the environment by chemical breakdown of DDT by sunlight (9). DDT sticks strongly to soil and does not dissolve easily into water, it begins to enter the environment by compiling within the adipose tissue of organisms making it an extremely persistent toxin.(explain a little more, which organisms start the biomag) This accumulation of DDT lead to bio-magnification in food webs, when DDT began to be used commercially, which affected predatory birds like ospreys, pelicans and eagles at the highest level of magnification (7). The contagion of DDT caused a reduction in the hardness of the bird’s eggs, because of a lack of calcium within the shell, and therefore widespread devastation in the population as the eggs all broke before ha...
Human civilization is evolving in the fields of science, engineering, architecture and medicine. The population because of these societal advances has allowed individuals to live longer sub healthy lives. Life improvements via transportation have been significantly enhanced because of breakthroughs in metal alloys which are used in car manufacturing. Or the usage of ether (ROR) extracted from corn to support the decline of gasoline. Individuals that live longer are thus able to experiment with different compounds seeking only to further improve on civilization. However, the more advanced our civilization becomes the greater the unknown risk of chemical exposures. The U.S. Environmental Protection Agency (EPA) and the U.S. Department of Defense (DoD), in various publications, have defined an emerging contaminate as a chemical or material that is characterized by a perceived, potential or real threat to human health. A contaminant may also be emerging because of the discovery of a new source or new pathway to humans and/or a new detection and treatment method (DoD 2006). Nevertheless, the USGS defines emerging contaminates as any synthetic or naturally occurring chemical or any microorganism that is not commonly monitored in the environment. These EC's are thought to have the potential to enter the environment and cause known or suspected adverse ecological and or human health effects. The Environmental Council of the states recently completed a survey of how states agencies currently defined and address emerging contaminates (Jones and Graves 2010). It was found that the definition varied by the state but no state had a clear definition of emerging contaminates and each lacked defined programs to deal with t...
From the research, Since 1996, the EPA has been involved in international negotiations to control the use of DDT and other POPs in all parts of the world. Under
One of the primary ways through which humans have caused significant modifications to the wildlife and their habitat is pollution. Pollution results from changes occurring to the physical and chemical characteristics of the environment leading to a harmful influence on wildlife and can cause deaths or an impairment to their health. Marine ecosystems are subject to chemical pollution from sources such as run-off, sewage, radioactive waste, oil drilling, and inadvertent dumping. Dachs and Mejanelle (2010), authors of “Organic Pollutants in Coastal Waters, Sediments, and Biota: A Relevant Driver for Ecosystems During the Anthropocene?,” state that despite the total number of synthetic chemicals not having
In addition to their many adverse effects on the human body, flame retardants also represent a hazard to the environment. They have similar effects on other animals as they do on humans. Even after certain types of flame retardants’ production was stopped after the discovery of their dangerous effects, they are still being detected in the environment, and are therefore still disturbing the ecosystem. (Guigueno,
Walton, D. W. H. and J. Shears, 1994, The need for environmental monitoring in Antarctica: baselines, environmental impact assessments, accidents and footprints. International Journal of Environmental Analytical Chemistry 55: 77-90.
Pesticides are contaminating the Earth’s water supplies. There are seventeen pesticides found in twenty-three state’s water supplies right now. Scientists at Cornell University conclude that 99% of pesticides miss the intended source and find their way into the water, air and soil. Most of the pollution isn’t strong enough to create an immediate impact on humans so the wildlife is the primary target to these contaminates. Animals such as the European Starling birds are constantly being tested and found that they are greatly affected both behaviorally and psychologically.