All living things are part of the food chain… no exceptions. Although we experience this principle of dependency daily, it usually gets ignored unless something disrupts the chain and results to detrimental consequences such as food poisoning that may lead to human fatalities or illnesses. Heavy metals are a part of nature and some are even beneficial to the human body but as with most things, too much concentration can have its adverse effects. What Are Heavy Metals? Heavy metals are found in rocks and soils but these may also accumulate in water forms
when these solid objects get broken down in time. The term heavy metal means any “metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations. (ILPI, 2007, par. 1) Some of the heavy metals that are being considered as threatening are arsenic, cadmium, chromium, copper, lead and mercury. These heavy metals which can also be called minerals have been present in the environment in safe amounts until industrialization has initiated mining activities and technological advances that altered their presence in the food chain.
Some of the products that elevated these heavy metals to possible intolerable levels are leaded gasoline and silver-mercury tooth amalgam. (Haas, n. d. , par. 5) Unfortunately, heavy metals cannot be destroyed except through radiation. It is therefore necessary to control its content and the way it is distributed in man’s environment especially when the food chain is concerned. How Do Heavy Metals Seep Into The Food Chain? There are many natural ways by which heavy metals enter the food chain.
Nature can release heavy metals from boulders and other rock formations by weathering and eventual breakage or erosion. Volcanic eruptions can also release these heavy metals into the air which will eventually accumulate around the surrounding habitat of many living organisms. Acidic rains can also break down soils and release heavy metals into streams, lakes, rivers and ground water. (Lenntech, 2006, par. 4) Man also has had a hand in the spillage of heavy metals in his environment. Lead paint and water pipes have been a source of many health problems and intoxications.
Copper, for example, can contaminate drinking water because of the copper-based pipes it passes and also from purifying agents that are intended to control the presence of microorganisms. Sewage sludge disposal unto farms is also a means that was originally a good way of garbage disposal but it can also be a path for certain nutrients to seep through the soil in larger quantities that may not be so beneficial after all. In Ohio, for example, sludges are considered rich in nitrogen and phosphorus which are significant sources of nutrients to farms in the vicinity of the sewage treatment plants.
(The Ohio State University, n. d. , par. 1) However, it has been found that it also contains unnecessary amounts of cadmium, copper, nickel, zinc and lead that can deter the healthy growth of botanical organisms and contaminate the food chain. Cadmium is the one that is easily absorbed by plants and copper is toxic to livestock. These heavy metals can also contaminate the soil when these are applied as fertilizers and pesticides. Automobile exhausts, although not directly affecting the food chain, can also cause illnesses because of its lead content.
Burning fossil fuel like coal, garbage and even tobacco can also release heavy metals like cadmium into the environment. (Contaminants Division, n. d. , par. 5) Man and nature can go hand in hand in releasing heavy metals in the environment. A factory in China, for example, can emit these toxic minerals in the air and the wind can carry it over to bodies of land and water in Russia. Because of this fact, it is harder to study the sources of heavy metal contamination in different locations. Bioaccumulation and Biomagnifications
There are two terms that are being used to show the problems that we undergo due to heavy metal contamination. These are biomagnifications and bioaccumulation. Biomagnification is the addition of intoxicating quantities of minerals when animals eat prey that could have been contaminated by heavy metals. Bioaccumulation, on the other hand, is an increase in the concentration of a chemical in a biological organism over time, compare to the chemical’s concentration in the environment. (Wageningen University, 2007, par.
2) This means that the bodies of the contaminated organisms accumulate more of these toxins than what they are able to secrete or eliminate and the build up can cause many negative consequences. Biomagnification, as implied, is a step in the food chain while bioaccumulation pertains to the heavy metal content within a living organism in relation to its habitat. Methyl mercury, for example, is a heavy metal that can contaminate rivers. Marine organisms may make the mistake of taking the heavy metal. These organisms are usually eaten by fish.
When a fish eats a contaminated marine organism, it cannot excrete the methyl mercury from its body anymore. The more contaminated organisms it eats, the more the methyl mercury accumulates within its body. Little fishes that have eaten these organisms can also be eaten by bigger marine creatures. The animals that are on top of the food chain stands to receive the consequences. Should a human, catch a contaminated fish, mercury poisoning will be inevitable and probably be even fatal. It was once assumed that heavy metals on the ground can bind tightly with soil particles and thus avoid being taken in by organisms eating on the soil.
However, a study of snails on cadmium-contaminated soil was made by Renaud Scheifler and his team of soil biologists at the University of Franche-Comte which showed that after two weeks, the snail’s tissues were found to have absorbed 16 percent of cadmium. (Coghlan, 2002, par. 4) In other words, it is not true that heavy metals cannot be accessed by organisms when it is bound to soil particles. Thus, heavy metals can also enter the food chain through the soil. The human body can easily eliminate toxic substances taken in low doses but it can also sometimes confuse heavy metals for other helpful minerals.
Cadmium, for example, can be mistaken for zinc and lead for calcium. Although some of these minerals’ properties are the same, cadmium and lead cannot replace the functions or benefits that zinc and calcium provide. Thus, some essential body functions may not be carried out and heavy metals may also accumulate within. Humans are equipped with a good maintenance system but if our natural means of eliminating these heavy metals from our system is hampered because of overdose and continued exposure, there is a possibility of abnormalities or even fatalities if not treated properly.
Effects of Heavy Metals to Humans Different heavy metals have unique effects on the living organisms that intake it. In the 1950s, many people in Japan began to experience a painful disorder called “itai-itai” which they discovered was a result of cadmium exposure due to industrial wastes. Cadmium can also have other effects such as the following: damage to the kidney, susceptibility to anemia, renal dysfunction, lung diseases that can lead to lung cancer, osteoporosis and osteomalacia.
Animals have been studied and showed that cadmium also increases their blood pressure but it has not been proven enough to affect humans the same way. Mercury and lead can both accumulate in the kidney, liver and spleen which can affect these organs’ functions. Low-level exposure can irritate the skin and cause ulceration. (Lenntech, par. 19) In 1932, people from Minimata Japan experienced what is now known as the Minimata Syndrome which was a direct effect of mercury contamination of marine life which the Japanese loved to eat.
Over 500 people died because of this disruption in the food chain. Copper is needed by the body but unusual doses can result to anemia, damages to the liver and kidney, plus stomach pain. Chromium can also accumulate in marine creatures and can cause considerable damages to the human kidney, liver and nerve tissues. Selenium is needed for some human body processes but overdose can damage the nerves, result to over fatigue and increased moodiness. Harder to correct health problems that may arise include loss of fingernails, damages to organ tissues and the nervous system.
One of the most important links in the general food chain is the plant species. However, heavy metal contamination can cause very sensitive kinds of plants to die. (Velky, n. d. par. 1) When this happens, organisms that rely on these botanical creatures will have a food shortage. Plants who may survive contamination get the chance to be eaten by other living creatures that can start the problems of biomagnifications and bioaccumulation. Humans are susceptible to higher levels of pollutants through ingestion because we are at the top of the food chain.
When plants and the soil from which many living things get food from becomes contaminated with toxic chemicals, these pollutants can be carried and accumulated in each animal that enters the food chain before man finally eats the one with the most quantity at the end of the chain. Heavy metals, as previously mentioned, can affect internal organs, the brain and even the development of young children. Pregnant women can bear ill or handicapped children as a result of heavy metal contamination of their food. For these innocent babies, the effect of these pollutants will remain with them for the rest of their lives.
Prevention or Solution Since these heavy metals are important for other natural reasons and can only be broken down through radiation, we cannot easily just find technology that will eradicate them. We can only try to control them by studying more about how these affect the human population and how they become a dangerous part of the food chain. We can develop more studies as to which plants are more resistant to heavy metal contamination so that we can adapt our choices of agricultural products in industrial territories. (Velky, par. 3)
Governments concerned with the environment can also form agreements such as the “Heavy Metal Protocol” initiated by Canada which seeks to necessitate the use of environmental-friendly technology to lessen heavy metal pollution from industrialized factories. To avoid direct poisoning from toxic materials, it would be wiser to eat younger fish or smaller marine animals that could not have accumulated many chemicals yet from the food chain. It might also be smarter for people to eat animals that are not predators to avoid being the last link in a contaminated food chain.
It would also be better to listen and follow health advisories regarding food toxicity rather than risk food poisoning. Conclusion Technology and nature can cook up a dangerous recipe when heavy metals are concerned. Man has to learn to control wastes and learn more about pollution to be able to make wiser decisions regarding many things that affect the food chain. If the food chain is not properly secured, it can be assumed that the human population will experience short-term, long-term and fatal consequences that could have been otherwise avoided with good principles and information. Rough Draft
Introduction: All living things are essential in the food chain. Heavy metals are natural necessities but can be poisonous if taken in overdosed amounts. What are Heavy Metals: Nature provided man with heavy metals in natural land forms like rocks and soil. These minerals can be released as the land forms are broken down by weather and time. Man also has increased heavy metal contamination through technology, mining and industrialization. Heavy metals are not easily destroyed unless by radiation. Therefore, man has to learn how to control the quantity of these heavy metals in his environment.
How Do Heavy Metals Seep Into the Food Chain? Nature can release these when rock formations are broken, through erosion, volcanic eruptions and acidic rain. Man can contaminate his environment by improper disposal of wastes such as sewage sludges, irresponsible use of technology which emits poisonous gas like lead. Nature and man can also assist each other in contaminating the earth too. Bioaccumulation and Biomagnifications: Biomagnification happens when a contaminated prey is eaten by another living creature.
Each of the biomagnifications in the food chain allows the accumulation of the heavy metal to increase until the end eater of the chain suffers the most quantity of toxic material ingested. This is bioaccumulation. Scientists are also proving that organisms can get these toxic wastes from the soil even when it was believed that heavy metals can bind themselves well to soil particles so that they become non-bio-accessible. This was refuted by a study in France. The human body also accepts heavy metals like cadmium and lead because these are mistaken for zinc and calcium which have similar properties.
However, due to its differences, the functions aided by zinc and calcium are not met by cadmium and lead which results to devastating consequences. Effects of Heavy Metals to Humans: Different minerals have different effects. Plants, which are a very important part of the food chain, may also die because of contamination and this can affect those who eat it. Humans can die because of contamination. Should a victim live, serious consequences like birth defects for babies and handicaps may form.
Prevention or Solution: Research must be done to find which plants can adapt to contamination and not before crops are planted near industrialized areas. Prevention and finding ways to control waste disposal are also recommendable. Learning to choose which food to eat can also save one from food poisoning. Conclusion: Man needs to learn how to control or manage waste disposal to protect and survive in the food chain.
References
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