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health and pollution > glossary
GlossaryAcid deposition: The airborne transport and descent to earth of acids and acid-forming chemicals, particularly those released by power plants, industry, and vehicles.
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AIDS: Acquired immune deficiency syndrome - a fatal disease caused by a virus (HIV) which destroys the immune system's ability to fight off infection.
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Algal bloom: Abnormally increased biomass of algae in a lake or river. Algal blooms occur naturally in spring and early summer, when the rate of reproduction of the algae outstrips that of their consumers. However, the most serious algal blooms are associated with human activities. Phosphates and nitrates carried into waterways in sewage, agricultural fertilisers and detergents, provide the nutrients that cause explosive growth in the algae population.
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Arsenic: A highly toxic element which exists in three forms � grey, black and yellow arsenic. It occurs naturally in the environment, being released from arsenic-bearing rocks through weathering. Arsenic accumulates in the environment so that small doses, relatively harmless individually, may eventually kill organisms - including people.
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Bio-indicators: Fish and other freshwater organisms from polluted waterways, for example, whose death or unusual behaviour may indicate the presence of hazardous pollutants that have escaped other detection methods.
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Bioaccumulation: The retention of non-biodegradable chemicals, or those that decay only slowly, in the bodies of organisms. Toxic metals such as lead (Pb) and mercury (Hg) and pesticides such as DDT are absorbed more rapidly than they are excreted and therefore accumulate in the body. Accumulation often takes place in specific locations, including bones, fatty tissues and organs, such as liver and kidney. The impact of bioaccumulation varies with the chemical and the organism involved, but it can cause death, prevent reproduction or increase susceptibility to disease.
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Carbon dioxide (CO2): One of the major greenhouse gases. Human-generated carbon dioxide is caused mainly by the burning of fossil fuels.
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Carbon tax: A policy that would tax fossil fuels according to the amount of carbon they contained. This would reduce the demand for fossil fuels in general and cause a realignment away from coal to less polluting natural gas, or renewable sources of energy.
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Carcinogen: A chemical or physical agent capable of causing cancer. Human activities can introduce chemical carcinogens such as chlorinated hydrocarbons or physical carcinogens such as asbestos or ionising radiation into the environment, but natural carcinogens such as toxic metals beryllium (Be), cadmium (Cd) and selenium (Se) are also present. There are two types of carcinogens: DNA-reactive carcinogens that alter the DNA of cells, and epigenetic carcinogens that do not react with DNA but may alter the immune system, cause hormonal imbalances or cause chronic tissue injury, all of which could lead to cancer. Carcinogens may be inhaled, ingested or absorbed through the skin.
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CFC�s (Chlorofluorocarbons): A group of chemicals containing chlorine (Cl), fluorine (F) and carbon (C), sometimes referred to by their trade name Freon. These synthetic compounds were used extensively for refrigeration and aerosol sprays until it was realized that they destroy ozone (they are also very powerful greenhouse gases) and have a very long lifetime once in the atmosphere (more than 100 years). The Montreal Protocol agreement of 1987 has resulted in the scaling down of CFC production and use in industrialised countries.
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Child mortality rate: The number of deaths among children under 5 years old per 1,000 children in the same age group.
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Chlorinated hydrocarbon: A class of synthetic chemicals first produced in the 1930s, including potent pesticides such as DDT and other compounds that do not break down in the environment and can be concentrated to poisonous levels in the fatty tissues of fish, birds, and mammals.
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Cholera: A bacterial disease caused by drinking water contaminated by sewage or eating food that has not been washed or is inadequately cooked. It is common in areas where the growth in population has outstripped the development of facilities for providing clean water or disposing of sewage. The problem is most severe in warm climates where high temperatures encourage the growth of the cholera bacteria.
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Coal: A black or brown combustible material composed of carbon (C), various carbon compounds and other materials such as sulphur (S). The most abundant of the fossil fuels, it was formed through the accumulation of vegetable matter over millions of years in environments (e.g. swamps, deltas) which reduced the rate of decay of the organic material and allowed the preservation of the solar energy to absorbed by it when it was growing. When coal is burned, it is that energy which is released.
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Conservation (nature): Protection against irreversible destruction and other undesirable changes, including the management of human use of organisms or ecosystems to ensure such use is sustainable.
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DDT (Dichlorodiphenyl-trichloroethane): A chlorinated hydrocarbon once widely used as a broad-spectrum insecticide. Introduced during the Second World War as a delousing agent, it proved very effective against diseases such as malaria, yellow fever and typhus, which were spread by insects. Over the longer term, serious side affects became apparent. Being a broad-spectrum product, it killed beneficial insects as well pests and could accumulate in the environment for perhaps 20 years. Although not soluable in water, it was soluable in fat, which allowed it to migrate up the food chain, where it accumulated in the body tissue of the predators. In birds it caused the thinning of eggshells, seriously reducing the breeding success of some species. By the mid-1960s, DDT was found to be widespread in the fatty tissue of the human population, passed on from mother to child through breast milk. Although the link between DDT concentration and human health was not clear, its potential to cause serious ecological disruption was recognised, and it was eventually banned or had its use severely restricted in the developed world.
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Development: A process of economic and social transformation that defies simple definition. Though often viewed as a strictly economic process involving growth and diversification of a country's economy, development is a qualitative concept that entails complex social, cultural, and environmental changes. There are many models of what 'development' should look like and many different standards of what constitutes 'success'.
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Dioxins: A group of approximately 75 chlorinated hydrocarbons formed as by-products of chemical reactions involving chlorine (Cl) and hydrocarbons. Dioxins appear as manufacturing impurities in some herbicides, wood preservatives and disinfectants, and are released into the environment during the incineration of chlorine-based plastics or as a result of the chlorine bleaching process in the pulp and paper mills. They are also released in industrial processes such as steel making. Dioxins are persistent chemicals, accumulating in soil and human fatty tissue. Health effects are varied and complex, ranging from skin problems, such as chloracne, to cancers, birth defects and serious immunology, neurological and behavioural problems.
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Ecological balance: Stability in an ecosystem achieved through the development of equilibrium among its various components. This does not imply that the community is static. It is subject to natural variations associated with ecological succession and other influences such as fire, disease and climate change, but the system is normally sufficiently elastic to make the necessary adjustments without major displacement of the balance. Human intervention that includes the introduction or removal of plants and animals, pollution of the environment and destruction of habitat is now a main cause of imbalance in many ecosystems.
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Ecology: Originally defined by Ernst Haeckel in 1866, ecology is the study of the relationships that develop among living organisms and between these organisms and the environment.
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El Ni�o/Southern Oscillation (ENSO): El Ni�o is the name originally given by local inhabitants to a weak warm ocean current flowing along the coast of Ecuador and Peru. ENSO is an extensive, intense, atmospheric and oceanic phenomenon affecting the tropical Pacific Ocean. It is associated with major anomalies in atmospheric circulation and rainfall patterns. El Ni�o occurs irregularly, but approximately every four years on average. ENSO events have impacts on fisheries, bird life and mainland weather.
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Emerging infectious disease: Disease that is new in the population or rapidly increasing in incidence or expanding in geographical range.
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Endangered species: Species of plants or animals threatened with extinction because their numbers have declined to a critical level as a result of overharvesting or because their habitat has drastically changed. That critical level is the minimum viable population (MVP), and represents the smallest number of breeding pairs required to maintain the viability of species.
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Endocrine-disrupting chemicals: Chemicals that can weakly mimic, or modify the action of human hormones. For example, some chemicals found in plastics, pesticides and industrial products are weakly oestrogenic, modifying the action of the female hormone. (Hormones are chemical messengers which govern human development and control or mediate vital bodily functions).
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Environment: A combination of the various physical and biological elements that affect the life of an organism. Although it is common to refer to �the� environment, there are in fact many environments eg, aquatic or terrestrial, microscopic to global, all capable of change in time and place, but all intimately linked and in combination constituting the whole earth/atmosphere system.
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Environmental Impact Assessment: A process which predicts the magnitude and importance of effects of a proposed activity on the environment, and on human health, and establishes conditions under which the activity may be undertaken. The result of the process may prevent the activity from proceeding if the potential effects are unacceptable.
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Environmental pollution: The contamination of the physical and biological components of the earth/atmosphere system to such an extent that normal environmental processes are adversely affected.
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Environmentally-sound: The maintenance of a healthy environment and the protection of life-sustaining ecological processes. It is based on thorough knowledge and requires or will result in products, manufacturing processes, developments, etc. which are in harmony with essential ecological processes and human health.
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Epidemic: Appearance of abnormally high number of cases of infection in a given population; can also refer to non-infectious diseases (e.g. heart disease) or acute events such as chemical toxicity.
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Epidemiology: The study of the distribution and determinants of health-related states or events in specified populations. Epidemiology is the basic quantitative science of public health.
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Erosion: Natural physical and chemical processes by which the soil and the rocks of the Earth's crust are continuously abraded and corroded. Most erosion results from the combined activity of several factors, such as heat, cold, gases, water, wind, gravity, and plant life. In some regions one of these may predominate, such as wind in arid areas. Erosion is grouped into two major divisions: geological erosion, which affects rocks as well as soil, and soil erosion.
"Erosion," Microsoft� Encarta� Online Encyclopedia 2001 http://encarta.msn.co.uk � 1997-2001 Microsoft Corporation. All rights reserved.
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Eutrophication: The occurrence of high nutrient levels in freshwater and marine ecosystems, usually resulting in excessive plant growth and the death of animal and some plant life due to oxygen deprivation.
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Fossil fuels: Fuels such as coal, oil and gas made by decomposition of ancient animal and plant remains which give of carbon dioxide when burned.
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Fuel cells: Fuel cells are electrochemical devices that convert a fuel�s energy directly to electrical energy through a chemical reaction instead of combustion. Fuel cells operate much like continuous batteries when supplied with fuel to the anode (negative electrode). Fuel cells forego the traditional extraction of energy in the form of combustion heat, conversion of heat energy to mechanical energy (as with a turbine), and finally turning mechanical energy into electricity (e.g. using a dynamo). Instead, fuel cells chemically combine the molecules of a fuel and oxidizer without burning, dispensing with the inefficiencies and pollution of traditional combustion.
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Global warming: The idea that increased greenhouse gases cause the Earth�s temperature to rise globally.
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Greenhouse effect: The cause of global warming. Incoming solar radiation is transmitted by the atmosphere to the Earth�s surface, which it warms. The energy is retransmitted as thermal radiation, but some of it is absorbed by molecules of greenhouse gases instead of being retransmitted out to space, causing the temperature of the atmosphere to rise. The name comes from the ability of greenhouse glass to transmit incoming solar radiation but retain some of the outgoing thermal radiation to warm the interior of the greenhouse. The �natural� greenhouse effect is due to the greenhouse gases present for natural reasons, and is also observed for the neighbouring planets in the solar system. The �enhanced� greenhouse effect is the added effect caused by the greenhouse gases present in the atmosphere due to human activities, such as burning of fossil fuels and deforestation.
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Greenhouse gases: Molecules in the Earth�s atmosphere such a carbon dioxide (CO2), methane (CH4) and CFCs which warm the atmosphere because they absorb some of the thermal radiation emitted from the earth's surface.
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Hantavirus: Type of virus; some hantaviruses are pathogenic to humans, causing severe illness. Rodents are a natural reservoir of all hantaviruses. Infection in humans occurs via inhalation or ingestion of materials contaminated with rodent excreta, although a tick vector may be involved.
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Hazardous waste: A class of waste materials that poses immediate or long-term risks to human health or the environment and requires special handling for detoxification or safe disposal. Both industrial and household wastes include hazardous materials.
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Heavy metals: Elements such as copper, lead, cadmium, mercury, and other toxic metals used in industrial processes and often released as both air and water pollutants. They may accumulate to hazardous concentrations in sediments and sludge.
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Hydrocarbons: Air pollutants that are important precursors of smog. These chemical compounds are generally released as unburned or incompletely burned residue when carbon-containing fossil fuels such as coal, oil, and natural gas are burned in car or truck engines.
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Methane: A simple hydrocarbon gas (CH4) produced during the decomposition of organic material under anaerobic conditions. It is the main constituent of natural gas and therefore and important fuel.
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OPEC: Organisation of Petroleum Exporting Countries. A group of Middle Eastern, Asian, African and Latin American nations that includes the world�s major petroleum producers and exporters. They came together in 1960, recognising the importance of oil as a source of future development, and with the intention of using their petroleum resources to advance their economic interests.
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Organochlorides: A group of organic compounds that contain chlorine (Cl). They have a variety of forms and uses including aerosol propellants, plasticisers, transformer coolants (PCBs) and food packaging (PCVs), but their greatest use was as pesticides, in the form of DDT, Aldrine and Lindane. However, with time many pests have developed immunity to them and it has also become clear that the characteristics that made them good pesticides � persistence, mobility and high biological activity � also posed dangers for the environment. Organochlorides accumulate in the fatty tissue of animals, and through biomagnification in the food chain may reach toxic levels in predators. Because of side effects such as sterility, birth defects, cancer and damage to the nervous system, they have been banned or had their use severely restricted in most parts of the world.
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Organophosphoruus compounds: A group of pesticides that work by blocking the central nervous systems of the organisms exposed to them. Malathion and diazonon are the most commonly used organophosphates. They are highly effective against insects, but break down rapidly in the environment and do not bioaccumulate. For these reasons, they are preferred over organochloride pesticides. Although generally considered safer than the organochlorides, they are highly toxic to humans and other mammals and may be carcinogenic.
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Ozone: An unstable and chemically-reactive gas containing three oxygen atoms, formed at high altitudes by the action of sunlight on molecular oxygen. Present at low concentration in the stratosphere, ozone absorbs ultraviolet radiation from the sun and reduces the amount of this damaging radiation that reaches the Earth's surface. Ozone is also formed at ground level - by the interaction of sunlight with exhaust gases from automobiles and industry, and by the action of sunlight on nitrogen oxides and hydrocarbons-where it is a primary component of smog that aggravates breathing problems and damages plants.
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Ozone hole: A region of the atmosphere over Antarctica where, during spring in the southern hemisphere, about half the atmospheric ozone disappears. The Ozone layer protects the earth�s surface from the effects of excess ultraviolet radiation. However, the growth in the volume and use of ozone-destroying chemicals, such as CFCs, has depleted the layer, allowing greater amounts of ultraviolet radiation to pass through to the earth�s surface, raising fears of the increased occurrence of skin cancer, eye damage and genetic mutation in terrestrial organisms. (Recently scientists have decreases of 10-20 per cent in ozone over the Arctic).
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Ozone hole: A popular name given to a phenomenon discovered in 1987, when scientists measured unexpectedly low ozone concentrations in the stratosphere above the South Pole during the Antarctic spring. It is now generally accepted that the loss of stratospheric ozone is caused by chemical reactions initiated by chlorofluorocarbons.
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Pandemic: Epidemic occurring over a very wide area, crossing international boundaries and usually effecting large numbers of people.
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Particulates: Very small solid exhaust particles emitted during the combustion of fossil and biomass fuels. Regarding respiratory diseases, particulates composed of acids, metals and polycyclic aromatic hydrocarbons are of greatest concern.
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Pathogen: Agent causing disease.
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Persistant Organic Pollutants (POPs): Persistant Organic Pollutants (POPs) are chemicals that remain intact in the environment for long periods, become widely distributed geographically, accumulate in the fatty tissue of living organisms and are toxic to humans and wildlife. POPs circulate globally and can cause damage wherever they travel. Such pollutants include toxix chemicals like DDT, Chlordane, and Endrin, Dioxins and Furans, among many others. The Stockholm Convention is a global treaty to protect human health and the environment from persistent organic pollutants (POPs). In implementing the Convention, governments will take measures to eliminate or reduce the release of POPs into the environment. For more information see: Ridding the World of POPs: A guide to the Stockholm Convention on Persistent Organic Pollutants
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Pesticides: Chemical products designed to kill or restrict the development of pests. They include fungicides, herbicides and insecticides. Pesticides range from relatively simple elements such as sulphur (S) to complex chemical compounds such as chlorinated hydrocarbons and may be broad-spectrum or narrow-spectrum agents. Pesticides also vary in their persistence in the environment, and in general, the longer they remain chemically stable the greater is their potential for environmental damage. The use of pesticides has undoubtedly benefited society, by preventing disease and improving the food supply. At the same time, ignorance of the environmental impact of pesticides, the indiscriminate use of certain products and inadequate control of the production and use of pesticides has created problems for wildlife and natural vegetation and has threatened human health.
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Petrochemicals: Chemicals derived from oil and natural gas � for example, ethylene, propylene, toluene � which act as feedstocks for the manufacture of products such as plastics, pesticides, fertilisers, antiseptics and pharmaceuticals. Petrochemicals play a very important role in modern society, but they also create pollution problems. Plastics are a major component of solid waste, for example, fertilisers contribute to eutrophication of lakes and rivers and pesticide residues in food and water present health problems.
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Petroleum: A mixture of naturally occurring hydrocarbons, that may exist in a solid (e.g. bitumen), liquid (e.g. crude oil) or gaseous state (e.g. natural gas). It commonly contains variable amounts of other chemicals such as sulphur (S) and nitrogen (N). Petroleum is the end-product of the partial decay of living organisms which once inhabited the world�s oceans. As they died they sank to the bottom of the oceans, where the anaerobic conditions allowed them to be preserved.
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Pollution: An undesirable contaminate (gas, liquid, noise, solid) which has been released into, and is now a part of, the environment.
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Polychlorinated Biphenyls (PCBs): PCB is a compound derived from biphenyl and containing chlorine that is used in electrical insulators, flame retardants, and plasticizers. Being stable they tend to accumulate in the environment, mainly by passage through the food chains. As a result, they are found in locations far removed from their industrial sources. Seals, fish and humans in the Arctic, for example, have traces of PCBs in their bodies. Tests have indicated that PCBs are carcinogenic and may impair the immune system. They area hazardous pollutants that are difficult to dispose of safely and have been banned in several countries.
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Population health: A measure of health status of populations, proposed in recent years to selectively replace use of the terms human health, which is more restrictive, and public health, which also encompasses preventive and curative measures and infrastructures.
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Primary pollutants: Substances known to be harmful as they are released to the environment.
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Resurging infectious disease: Disease that had been decreasing in population but which is now rapidly increasing in incidence again. Examples include: diptheria, malaria and cholera. In some cases, resurgence is due to decreases in active control programmes or surveillance activities.
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Secondary pollutants: Pollutants such as ozone, peroxyacetyl nitrate (PAN), and other compounds formed when nitrogen oxides and hydrocarbons react in the presence of sunlight.
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Smog: Originally a combination of smoke and fog, now used to describe other mixtures of air pollutants, especially ozone and other compounds formed when strong sunlight acts on a mixture of nitrogen oxides and volatile organic compounds from motor vehicle exhaust.
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Solar thermal energy: Energy produced by using the sun's rays to heat a gas or liquid that then performs useful work, such as powering an electrical generator. Electricity from solar thermal power plants is now nearly competitive in cost with electricity from conventinal fossil-fuel power plants.
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Sustainable development: Sustainable development has as many definitions as subscribers. In essence, it refers to economic development that meets the needs of all without leaving future generations with fewer natural resources than those we enjoy today. It is widely accepted that achieving sustainable development requires balance between three dimensions of complementary change:
- Economic (towards sustainable patterns of production and consumption)
- Ecological (towards maintenance and restoration of healthy ecosystems)
- Social (towards poverty eradication and sustainable livelihoods)
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Synthetic Chemcial: Pertaining to or involving chemical synthesis; (of an organic compound, a gem, etc.) produced by artificial synthesis, esp. in imitation of a natural substance; (of a fibre) manufactured from a chemically synthesized polymer.
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Toxin: Poison of animal or vegetable origin. Or poison formed in the body by pathogenic organism.
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Ultraviolet radiation: High energy, short-wave radiation lying between visible light and X-rays in the electromagnetic spectrum. It is usually divided into ultraviolet-A (UV-A) with wavelengths of 320-400 nanometres (nm), ultraviolet-B (UV-B) with wavelengths of 280-320nm and ultraviolet-C (UV-C) with wavelengths of 200-280nm. Ultraviolet rays are an important component of solar radiation. At normal levels it is an important germicide and is essential for the synthesis of Vitamin D in humans. At elevated levels, it causes sunburn and skin cancer, and can produce changes in the genetic make-up of organisms. It also has a role in the formation of photochemical smog. Most of the UV radiation which reaches the earth from the sun is absorbed by the ozone layer in the stratosphere. Thinning of the ozone layer, however, has increased the proportion of ultraviolet radiation � particularly UV-B � reaching the earth�s surface, giving rise to fears of an increasing incidence of skin cancer and other radiation-related problems.
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Urbanisation: Conversion of land from a natural state or managed natural state (such as agriculture) to an urban state.
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Vector: Organism that acts as an essential intermediate host or definite host for a human pathogen and that plays an active role in its transmission; for example, Anpheles species are vectors of malaria. This definition excludes mechanical carriers or infective materials (such as houseflies and cockroaches), strictly passive intermediate hosts (such as the snail hosts of schistosomiasis) and reservoir species (such as foxes in the case of rabies).
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Waste: Any material, solid, liquid or gas, that is no longer required by the organism or system that has been using it or producing it. Population growth, new lifestyles and a rapidly changing technology have contributed to an increase in the generation of waste and created serious waste disposal problems.
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Water-washed diseases: Diseases spread from one person to another due to inadequate supplies of water for personal hygiene. These include infections of the skin and eyes (e.g. trachoma) and infections carried by lice, e.g. louse-borne epidemic typhus.
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WHO (World Health Organisation): A UN agency created in 1948 to deal with global health issues and to achieve as high a level of physical, mental and social well-being as possible for peoples of the world. It is involved in a variety of environemental studies, including the impact of climate change and ozone depletion on health, in conjunction with other agencies such as the World Meteorological Organisation (WMO) and the United Nations Environment Program(UNEP).
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World Commission on Environment and Development: Established by the United Nations General Assembly in 1983 to examine international and global environmental problems and to propose strategies for sustainable development. Chaired by Norwegian Prime Minister Gro Harlem Brundtland, the independent commission held meetings and public hearing around the world and submitted a report on its inquiry to the General Assembly in 1987.
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World Summit on Sustainable Development (WSSD): The World Summit on Sustainable Development takes place from 26 August - 4 September 2002 in Johannesburg, South Africa. Governments, UN agencies, and civil society organisations will come together to assess progress since the UN Conference on Environment and Development held in Rio in 1992 (hence the title 'Rio + 10' for the Johannesburg meeting). Sustainable development is defined in the report from the Rio meeting as being 'economic progress which meets all of our needs without leaving future generations with fewer resources than those we enjoy'.
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Zero-discharge technology: Technology that comprises industrial processes designed to prevent the release of any pollutant harmful to the environment (e.g., recovery of solvents, cleaning rinses, and other chemicals used in manufacturing by collecting them and removing dissolved and suspended materials so the liquids can be reused.
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