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Toxic Capacity
Toxic capacity can be defined in many ways. The first way can be defined as the toxicity of a substance in relation to a specific organism, such as humans. Another way we can define toxic capacity is the concentration of toxic substances that can be contained in an organism without showing signs of poisoning or dying. It is important to note that once a substance’s toxic capacity has been surpassed, adverse affects may occur, such as illness or death. The testing of toxic capacity in ecosystems and organisms is difficult as procedures may cause harm and is therefore unethical, thus many questions still remain about specific toxic capacities.
Toxic Substances
The toxic substances that contribute to an organism’s toxic capacity come in many different types of materials. These can range from safe substances, such as vitamins and minerals essential to a proper nutrition, to chemicals like pesticides. Examples of toxic compounds include: acids, volatile organic compounds (VOCs), dioxins, mycotoxins, heavy metals, drugs, bases, paints, dyes, ammonia, polychlorinated biphenyls (PCBs), and chlorine [1] [2] [3]. The toxicity in an environment leads to the build-up of toxic substances within an individual’s body. Toxic capacities for various substances are unique from one another, and the toxic capacity for all species are different from individual to individual. For screening toxicity levels in the environment for these various substances and organisms, certain types of environmental data, such as groundwater, sediment, and fish tissue, may better predict specific classes of chemicals present in the environment [1]. In the United States, when testing toxicity readings from human adipose (fat) tissue, certain areas, such as southeast regions, were exposed to more toxic substances than elsewhere in the country [1]. Levels of exposure vary by geographic region with populations in some regions exposed to greater amounts of certain classes of compounds than others [4]. As humans, we need to be aware of high-risk materials and areas in order to manage toxic substances responsibly. Potentially harmful substances found in the home such as antibiotics, detergents, drugs, disinfectants, and perfumes can be found in Canadian lakes and streams. These synthetic chemicals and pollutants can be concentrated in ground water and surface water, in the air, in cosmetics, as well as soft plastic materials such as children’s toys. This indicates that it is not just our species that we are exposing these household, everyday toxic substances to, but entire ecosystems that surround us. [5]. Evidence also shows that incidents during the transportation of hazardous substances can cause injuries, such as respiratory and gastrointestinal problems, chemical burns, eye irritation, as well as death to workers and the public [3]. Findings suggest that the leading causes of incidents are human error and equipment failure, which can occur by ground transport, rail, water, pipeline, and others [3]. There are also many toxic substances found in animal feed which can accumulate in our bodies, and in extreme cases threaten our toxic capacities [2]. Cheap, analytical screening techniques to check feeds for all possible contaminants are still not available [2]. The safety and protection of the environment, animals, and human-kind is dependent on our willingness to take part in the global reduction of toxicity.
Mycotoxins
Mycotoxins are small molecular natural substances, produced by fungi that are toxic to humans and animals in low concentrations. Mycotoxins fall into the categories of antibiotics and phytotoxins. [6] Mycotoxicosis is the toxic effect of mycotoxins on animal and human health. Sensitivity to mycotoxins range depending on the species exposed. However, the severity of mycotoxicosis depends heavily on the influence of the toxicity of the substance, the extent of the exposure, the age and the nutritional status of the individual, and the possible effects of other chemicals to which the individual has been exposed. [7]. Mycotoxicosis, like all other illnesses presents many types of symptoms. Exposure to mycotoxins may have a large variety effects on humans and animals alike. Mycotoxicosis may result in either acute toxicity or chronic toxicity. Symptoms may include vomiting, diarrhea, hemorrhage, difficulty breathing, chest pain, blisters, headache, fatigue, dizziness, other endocrine disruption, and possibly death. In animals, toxic overload has been shown to alter production of goods such as milk and wool, it has altered animals’ abilities to reproduce and also to grow. [6]. There are many ways humans are able to come into contact with mycotoxins each and every day. Mycotoxins are mostly transmitted by ingestion. Mycotoxins may also be transmitted through skin contact or by inhalation. [8]. Mycotoxins are relatively easy to come into contact with as they reproduce in areas that have hot and humid climates, they grow in temperate zones, in areas that are infested with insects, in areas where droughts are common, in fungicides and in fertilizers. [6]. The most common mycotoxins are Aflatoxins (AF), Ochratoxins (OT), Trichothecenes, Zearalenone (ZEN), Fumonisins (F), Tremorgenic Toxins and Ergot Alkaloids. [7], [6].
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Vitamin Toxicity
Although there are many environmental toxins, there are nutritional toxins as well. In the past, vitamin toxicity was more common than in the present. However, there is still a risk. Vitamin toxicity, or hypervitaminosis, happens when too much of the vitamin is consumed and excessive amounts of the particular vitamin build up in the body. The most common type of toxicity through vitamins is through the vitamins that get stored in your fat and build up over time. Vitamin A toxicity is the most common form of vitamin toxicity. Vitamin A is present in many forms in different foods. One such form is carotene in carrots, which is the safest way to consume vitamin A. When you eat too much of this vitamin (more than 1000 times the nutritionally recommended amount) the liver cannot break it down and this excess will cause intoxication [9]. The signs of a vitamin A overdose are dry skin, brittle and course hair, dry scaly skin around the mouth, and in some cases cirrhosis [10]. Another prominent vitamin that can become toxic when taken in excess is vitamin D. Again, Vitamin D is not a prevalent issue in the present but can still pose a risk. In the past vitamin D fortified foods in the United States and Europe have caused vitamin D overdose. Hyperglycemia, the buildup of calcium in your blood, is responsible for producing most of the symptoms of vitamin D toxicity which may include gastrointestinal disorders like anorexia nervosa, diarrhea, constipation, nausea, and vomiting. Other symptoms of vitamin D toxicity include bone pain, drowsiness, continuous headaches, irregular heartbeat, loss of appetite, and muscle and joint pain. Additionally, are other symptoms that are likely to appear within a few days or weeks include frequent urination (especially at night), excessive thirst, weakness, nervousness and itching and kidney stone [11].
Control/Regulation of Toxins
Many of the symptoms that can result from toxin consumption, can be avoided by properly controlling and regulating the substances, that humans allow to enter the environment. Every day, humans engage in activities that are harming our environment by creating build-ups of toxic material. These activities are damaging our ecosystem functions, human and wildlife health. Activities such as agricultural production, urban development, energy production and reutilization of resources such as wastewater, are all capable of releasing toxic substances into our environment. [12].In order to control the exposure and to minimize the effects of mycotoxins, there are several steps that can be taken, such as good agricultural practices, biological control, chemical control, decontamination, breeding for resistance, and surveillance and awareness creation. [6]
Toxins in The Environment
Without proper regulation and monitoring, such phenomenons such as bioaccumulation and eutrophication may occur. Bioaccumulation is the gradual build-up of a chemical in a living organism over time. This occurs either because the chemical is taken up faster than it can be used, or because the chemical cannot be metabolized. [13]. Bioaccumulation can result in a magnified toxin which, as a result of the food web, is most harmful to top predators. This can lead to the loss or extinction of many species in an ecosystem. Eutrophication is the process by which a body of water becomes over-enriched in dissolved nutrients that stimulate the growth of aquatic plant life which eventually results in the depletion of dissolved oxygen. [14]. Eutrophication can occur when waterways are excessively loaded with nitrates and phosphates from run-off water released in agricultural, industrial and domestic processes. [12]. Eutrophication affects plant and vegetation growth, nutrient pollution and causes changes in biodiversity and in the food web. Other effects that toxins expose the environment to are impaired soil fertility, such as acidic soil due to increased levels of Manganese [15] and DNA damage. As one study shows, a number of chemicals have been tested on live aquatic animals and have been proven to cause DNA damage. These chemicals can be grouped into four classes: 1. Act directly on DNA 2. Metabolites cause DNA damage 3. Cause the production of reactive oxygen species that can damage DNA 4. Inhibit DNA synthesis and repair. [16]
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How to Reduce Toxicity in the Environment
Additionally, it is extremely important to be aware of established methods in which the world is attempting to reduce this toxicity around us. To reduce transport accidents associated with toxic exposure, action can be taken at many levels, such as developing emergency response plans before accidents occur, ensure employees and first responders working around toxic substances undergo continuous job safety training, preventive maintenance on equipment and vehicles used, and avoiding storing or transporting these substances in high-risk areas [3]. Cooperation between research, industry, and government in the field of green chemistry will also maximize the use of available resources and accelerate the adoption of sustainable products and processes in chemical industries, helping reduce production of hazardous substances [17]. In Canada, organizations and leaders, such as the Canadian Cancer Society and the government, are achieving toxic use reduction (TUR) by supporting public campaigns, funding research, promoting pollution prevention programs, passing bills for toxic use reduction, and advocating for the reduction, proper labeling, and better standards for toxic substances [18]. Methods like these help many industries around the world reduce the toxic impact on the environment. Reducing toxicity in the environment on a large scale is effective, but it is also essential that humans take an individualized approach in reducing the toxicity in the environment. There are many suggestions for individuals for lowering the pressure on toxic capacities in the environment. Actions such as avoiding products with high Volatile Organic Compound (VOC) content, buying fresh, organic food, and using natural pest control methods are examples of ways in which to personally lower toxic substance output into the environment [19]. Other suggestions include turning off power on appliances when not using them, recycling, choosing energy-efficient appliances, and driving vehicles efficiently [20].
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Exploring the harmful effects and controversial uses of DDT
DDT was first synthesized in 1874 but its insecticide qualities were not discovered until 1940 by a Swiss chemist, Dr. Paul Müller, who discovered that it could be sprayed on walls and would cause any insect to die within the next six months, without any apparent toxicity to humans. During WWII, DDT, because of effectiveness in eradicating insects, quickly became the chief weapon used by the US military to protect troops in areas laden with vector-borne diseases such as typhus and malaria. DDT was so effective at stopping the spread of insect borne diseases that it became the most important pesticide responsible for maintaining human health through the next two decades [21]. However, due to the chemical make-up of DDT, it is very persistent, biodegrades slowly, builds up in fatty tissues, and cause adverse health effects on wildlife [22]. DDT can build up in the fatty tissues of wildlife and humans, however while it is stored in fat there are no adverse health effects. When a person goes through a period of fat loss or starvation then the breakdown of DDT can enter the blood stream and be toxic to the liver and nervous system. When DDT accumulates in the body it is excreted through urine, feces, and break milk. DDT was banned in the United States because it was brought to the public’s attention that it had environmental affects and health risks [23]. Although DDT is not permitted to be used in the United States or Canada, it is still produced in the US and is sold to foreign countries. It is used for the regulation of lice and other insects that pose health problems or insects that pose problems to crops.
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- ^ a b c Kan, C. and Meijer, G. 2006. The Risk of Contamination of Food with Toxic Substances Present in Animal Feed. Animal Feed Science and Technology 133: 84-108, [2]
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- ^ X, Xin, et al. 2016.Manganese Oxide Affects Nitrification and Ammonia Oxidizers in Subtropical and Temperate Acid Forest Soils.Catena: 24-30, [12]
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- ^ Thomas Dunlap. 2014. Part two-Learning about DDT, and Part three-Changing directions. DDT: Scientists, Citizens, and Public Policy. 1st edition. Princeton University Press,[20]