Heavy Metals; Illegal offspring of industries For biosphere

Environment can be referred to the surroundings within which humans exist. These are made up of: the land, the water and the atmosphere of the earth; microorganisms, plant and animal life; any part or combination of the first two items on this list and the interrelationships among and between them and the physical, chemical, aesthetic and cultural properties and conditions of the foregoing that influence human health and well-being. It is also characterized by a number of spheres that influence its behavior and intrinsic value. The most important sphere of the environment is the biosphere because it harbors the living organisms. This is the sphere where you find living organisms (plants and animals) interacting with each and their nonliving environment (soil, air and water). In the late centuries, industrialization and globalization have impaired pristine environments and their ability to foster life. This has introduced components that compromise the holistic functioning of the environment and its intrinsic values [1]. An environment can be polluted or contaminated. Pollution differs from contamination; however, contaminants can be pollutants, and pose detrimental impact on the environment. From literature, pollution is defined as the introduction by man, directly or indirectly, of substances or energy into the environment resulting in such deleterious effects as harm to living resources, hazards to human health, hindrance to environmental activities and impairment of quality for use of the environment and reduction of amenities. Contamination on the other hand is the presence of elevated concentrations of substances in the environment above the natural background level for the area and for the organism. Environmental pollution can be referred to undesirable and unwanted change in physical, chemical and biological characteristics of air, water and soil which is harmful for living organisms—both animal and plants. Pollution can take the form of chemical substances or energy, such as noise, heat or light [2]. Pollutants, the elements of pollution, can either be foreign substances/energies or naturally occurring contaminants. Environmental pollutants continue to be a world concern and one of the great challenges faced by the global society. Pollutants can be naturally occurring compounds or foreign matter which when in contact with the environment cause adverse changes. There are different types of pollutants, namely inorganic, organic and biological. Irrespective of pollutants falling under different categories, they all receive considerable attention due to the impacts they introduce to the environment. The relationship between environmental pollution and world population has become an inarguable directly proportional relationship as it can be seen that the amount of potentially toxic substances released into the environment is increasing with the alarming growth in global population. This issue has led to pollution being a significant problem facing the environment. Industrial, agricultural and domestic wastes contribute to environmental pollution, which cause adverse harm to human and animal health. From such sources, inorganic pollutants are released. Inorganic pollutants are usually substances of mineral origin, with metals, salts and minerals being examples [2]. Studies have reported inorganic pollutants as material found naturally but have been altered by human production to increase their number in the environment. Inorganic substances enter the environment through different anthropogenic activities such as mine drainage, smelting, metallurgical and chemical processes, as well as natural processes. These pollutants are toxic due to the accumulation in the food chains [3]. Organic pollution can be briefly defined as biodegradable contaminants in an environment. These sources of pollution are naturally found and caused by the environment, but anthropogenic activity has also been contributing to their intensive production to meet the human needs. Some of the common organic pollutants which have been noted to be of special concern are human waste, food waste, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), pesticides, petroleum and organochlorine pesticides (OCPs) [4]. Organic pollutants have gained attention as they have become a major problem in the environment. Properties of organic pollutants, amongst others, such as high lipid solubility, stability, lipophilicity and hydrophobicity have recently made organic pollutants termed persistent. These properties give organic pollutants the ability to easily bioaccumulate in the different spheres of the environment, thus causing toxicological effects. Biological pollutants are described as pollutants which exist as a result of humanity’s actions and impact on the quality of aquatic and terrestrial environment. This type of pollutants include bacteria, viruses, moulds, mildew, animal dander and cat saliva, house dust, mites, cockroaches and pollen. Studies have documented different sources of these pollutants, including pollens originating from plants; viruses transmitted by people and animals; bacteria carried by people, animals, and soil and plant debris. Although there is no specific definition of a heavy metal, literature has defined it as a naturally occurring element having a high atomic weight and high density which is five times greater than that of water. Among all the pollutants, heavy metals have received a paramount attention to environmental chemists due to their toxic nature. Heavy metals are usually present in trace amounts in natural waters but many of them are toxic even at very low concentrations. Metals such as arsenic, lead, cadmium, nickel, mercury, chromium, cobalt, zinc and selenium are highly toxic even in minor quantity. Increasing quantity of heavy metals in our resources is currently an area of greater concern, especially since a large number of industries are discharging their metal containing effluents into fresh water without any adequate treatment. Heavy metals become toxic when they are not metabolized by the body and accumulate in the soft tissues. They may enter the human body through food, water, air or absorption through the skin when they come in contact with humans in agriculture, manufacturing, pharmaceutical, industrial or residential settings. Industrial exposure accounts for a common route of exposure for adults. Ingestion is the most common route of exposure in children. Natural and human activities are contaminating the environment and its resources, they are discharging more than what the environment can handle Heavy metals are naturally occurring elements that have a high atomic weight and a density at least 5 times greater than that of water. Their multiple industrial, domestic, agricultural, medical and technological applications have led to their wide distribution in the environment; raising concerns over their potential effects on human health and the environment. Their toxicity depends on several factors including the dose, route of exposure, and chemical species, as well as the age, gender, genetics, and nutritional status of exposed individuals. Because of their high degree of toxicity, arsenic, cadmium, chromium, lead, and mercury rank among the priority metals that are of public health significance. These metallic elements are considered systemic toxicants that are known to induce multiple organ damage, even at lower levels of exposure. They are also classified as human carcinogens (known or probable) according to the U.S. Environmental Protection Agency, and the International Agency for Research on Cancer. This review provides an analysis of their environmental occurrence, production and use, potential for human exposure, and molecular mechanisms of toxicity, genotoxicity, and carcinogenicity. Heavy metals in drinking water pose a threat to human health. Populations are exposed to heavy metals primarily through water consumption, but few heavy metals can bioaccumulate in the human body (e.g., in lipids and the gastrointestinal system) and may induce cancer and other risks. To date, few thousand publications have reported various aspects of heavy metals in drinking water, including the types and quantities of metals in drinking water, their sources, and factors affecting their concentrations at exposure points, human exposure, potential risks, and their removal from drinking water. Many developing countries are faced with the challenge of reducing human exposure to heavy metals, mainly due to their limited economic capacities to use advanced technologies for heavy metal removal. This paper aims to review the state of research on heavy metals in drinking water in developing countries; understand their types and variability, sources, exposure, possible health effects, and removal; and analyze the factors contributing to heavy metals in drinking water. This study identifies the current challenges in developing countries, and future research needs to reduce the levels of heavy metals in drinking water. When a person consumes excessive amount of arsenic or arsenicosis, it leads to poisoning. The semi- metallic chemical is found in groundwater all over the world. Arsenic poisoning leads to a number of health problems and at times may cause death if not treated on the right time. Considering the risks associated with arsenic poisoning, it is essential to install the best RO water filter for your home which can remove arsenic so that you drink safe and healthy water. In this blog, we discuss in detail the causes, health effects, symptoms and ways to prevent arsenic poisoning. Water pollution is the contamination of water sources by substances which make the water unusable for drinking, cooking, cleaning, swimming, and other activities. Pollutants include chemicals, trash, bacteria, and parasites. All forms of pollution eventually make their way to water. History has shown that advancements in materials science and engineering have been important drivers in the development of sensor technologies. For instance, the temperature sensitivity of electrical resistance in a variety of materials was noted in the early 1800s and was applied by Wilhelm von Siemens in 1860 to develop a temperature sensor based on a copper resistor. The high resonance stability of single-crystal quartz, as well as its piezoelectric properties, have made possible an extraordinarily wide range of high performance, affordable sensors that have played an important role in everyday life and national defense. More recently, a new era in sensor technology was ushered in by the development of large-scale silicon processing, permitting the exploitation of silicon to create new methods for transducing physical phenomena into electrical output that can be readily processed by a computer. Ongoing developments in materials technology will permit better control of material properties and behavior, thereby offering possibilities for new sensors with advanced features, such as greater fidelity, lower cost, and increased reliability. As noted in the preface, the Committee on New Sensor Technologies: Materials and Applications was asked to identify novel sensor materials that could benefit the manufacture and operation of advanced systems for the Department of Defense and the National Aeronautics and Space Administration and to identify research and development (R&D) efforts that could accelerate the development and incorporation of these emerging sensor materials in particular applications with potentially high payoff. To provide a foundation for its recommendations in these areas, the committee began by assessing the current status of sensor technologies. Early in this assessment, the committee found that applications, not materials, drive new sensor development. Therefore the committee identified a conceptual framework that could relate sensor materials to application needs within which the importance of particular sensor materials could be determined. Given the extensive body of published work relating to the broad, multidisciplinary subject of sensor technologies, the committee prepared a summary bibliography drawn from the recent literature. The bibliography includes review articles, books, and monographs relating to the wide range of sensor technologies. These references can form a basis from which a more detailed study of any particular sensing technology, principle, or application can be initiated. Several key journals dealing with sensing have been included in the bibliography; they are suggested as starting points for investigating the most recent developments and trends in sensor technologies. Additional information is available from the reference list at the end of each chapter. Despite the extensive published literature that treat the fundamentals of sensor technology, considerable ambiguity exists in sensor definition and classification, as illustrated by a recent buyer's guide for sensors in which two lists of sensor suppliers are provided, one based on properties sensed and the other on technologies used (Sensors, 1992). The latter list includes both physical phenomena (for example, acoustic, electrochemical, Hall Effect and infrared sensors), and material types (such as bimetallic, fiberoptic, thick-and thin-film, and zirconium oxide sensors). Understanding the physical or chemical effects that yield useful transduction is important in selecting and designing sensors. However, these effects by themselves are usually not sufficient to establish an unambiguous sensor classification, since typical sensors may use more than one effect. A simple example is a diaphragm pressure gauge. The diaphragm uses one form of mechanical energy to create another (pressure generates displacement and strain); however, the creation of an electrical signal from the displacement or strain can be accomplished using many approaches. The diaphragm could be made of a piezoelectric material, in which the air would induce an electrical charge; an inductive or capacitive effect could be employed to measure the charge related to the strain and the deflection and thereby infer the pressure. Thus understanding all of the possible field effects and features of transducer materials behavior provides the most complete set of sensor design options. In order to accelerate the incorporation of emerging sensor materials in new applications, it is critically important that the sensor materials community be able to readily identify sensing needs that candidate materials could fulfill. The formal study of sensor technology is plagued by ambiguity in definitions and terminology. This evolving field of endeavor is extraordinarily broad with nearly every scientific and technical discipline playing an important role. Thus, it should not be surprising that there is no unanimous concept of a sensor. Given the impossibility of presenting a universally accepted definition for sensors, the committee used terms and definitions that are generally accepted in the current technical literature to provide the basis for discussion in this report. (A complete tutorial on sensors and their transduction principles is beyond the scope of the present report.) The terms "sensor" and "transducer" have often been used as synonyms. The American National Standards Institute (ANSI) standard MC6.1 defines a transducer as "a device which provides a usable output in response to a specific measurand" (Instrument Society of America, 1975). An output is defined as an "electrical quantity," and a measurand is ''a physical quantity, property, or condition which is measured." In 1975, the ANSI standard stated that "transducer" was preferred to "sensor." However, the scientific literature has not generally adopted the ANSI definitions, and thus currently "sensor" is the most commonly used term. Therefore, the term "sensor" will be used throughout this report. The committee recognizes that, for the purpose of this report, the output of a sensor may be any form of energy. Many early sensors converted (by transduction) a physical measurand to mechanical energy; for example, pneumatic energy was used for fluid controls and mechanical energy for kinematic control. However, the introduction of solid-state electronics created new opportunities for sensor development and control, with the result that sensors today almost exclusively produce an electrical output for use in such applications as computer-based controls, archiving/recording, and visual display. This need for electrical interfacing is causing a broadening in the definition of a sensor to include the systems interface and signal conditioning features that form an integral part of the sensing system. With progress in optical computing and information processing, a new class of sensors, which involve the transduction of energy into an optical form, is likely. Also, sensors based on microelectromechanical systems may enable fluidic elements to operate as controls and actuation devices in the future. Thus the definition of a "sensor" will continue to evolve. The definition of a sensor does not precisely define what physical elements constitute the sensor. For example, what portion of a thermocouple is the sensor? Is it solely the bimetallic junction? Does it include the wires used for transmission purposes? Does it include any packaging or signal processing? On the basis of information in the current technical literature, the committee chose to adopt the following definitions: Sensor element: The fundamental transduction mechanism (e.g., a material) that converts one form of energy into another. Some sensors may incorporate more than one sensor element (e.g., a compound sensor). Sensor: A sensor element including its physical packaging and external connections (e.g., electrical or optical). Sensor system: A sensor and its assorted signal processing hardware (analog or digital) with the processing either in or on the same package or discrete from the sensor itself. In order to describe and characterize the performance of a sensor, a large and specific vocabulary is required. Several excellent references, which provide a basic review of transducer characteristics, are cited in the bibliography. Lion (1969) introduced a classification of principles according to the form of energy in which sensor signals were received and generated, which yielded a matrix of effects. In this book, we intend to investigate water pollution by heavy metals. Finally, we will review the methods for characterizing heavy metals by chemical sensors. So Ladies and gentlemen! Welcome to the age of pollution