Introduction
One of the byproducts of urban growth and development is the waste production. As per the report of the World Bank (2013), OECD countries produce almost half of the world's waste, while South Asia and Africa are listed as the regions producing the least amount of waste. The Basel Convention defines 'wastes' as substances or objects that need to be disposed of in accordance with the provisions of national law. European Waste Catalogue shows 850 types of wastes out of which 420 types of wastes have been classified as hazardous waste. Hazardous wastes are those wastes considered to be dangerous to the environment and living beings. These wastes may be in the form of solid, liquid, gas, dangerous pathogens, chemicals, heavy metals, sludge, radiation, and other toxins (UNEP, 2011). Hazardous wastes can cause several types of damages to the ecological system, environment and human health. This essay will discuss about different types of hazardous wastes, characteristics of wastes and their impact on the environment and human health.
The Definition of Hazardous Waste
In order for proper waste management, it is important to have a concrete definition of the hazardous waste so that these wastes can be controlled. The definition of 'hazardous' depends on the constitution, the physical form and chemical, physical and biological properties of the waste. However, there is no standard definition of hazardous wastes in the world as each country in the world has its own interpretation of what constitutes hazardous waste. United Nations Environment Programme (UNEP) defines hazardous wastes as wastes, which due to their chemical activity and toxic, explosive and corrosive characteristics, pose danger to the health and the environment (UNEP, 2011). The U.S. Environmental Protection Agency (2013) defines hazardous waste as waste that is potentially harmful and dangerous to human health and the environment. Any waste that meets one of the four characteristics of ignitability, corrosivity, toxicity, and reactivity is labelled hazardous by EPA (EPA #1, 2013). The Hazardous Waste Act of Australia defines hazardous waste as waste that has any of the characteristics of toxicity, eco-toxicity, infectiousness, explosiveness, poisonousness and flammability as mentioned in Annex III to the Basel Convention (White and Heckenberg, 2011).
Waste Classification
The waste classifications also vary among countries. The classification methods used for determining hazardous wastes are the origin of the hazardous wastes, their characteristics and their physical, chemical and biological properties. The US EPA has divided hazardous into the following types:
Listed Wastes: Listed wastes are those that have been listed as hazardous by the EPA. This list includes
- F List - hazardous wastes from non-specific sources generated during common manufacturing and industrial processes, such as wood preserving wastes and dioxin-bearing wastes,
- K List - wastes generating from specific industries such as pesticide manufacturing, ink formulation, primary aluminium production, iron and steel production, and explosives manufacturing),
- P List (chemicals acutely hazardous, such as commercial chemical products), and you List (chronically toxic, hazardous wastes such as discarded chemicals) (EPA#2, 2005).
Characteristic Wastes: Wastes that are not listed above, but have one of the four characteristics (ignitability, reactivity, corrosivity, or toxicity) considered hazardous by the EPA.
Universal Wastes: Pesticides, batteries, mercury-containing equipments such as thermostats and lamps.
Mixed Wastes: Mixed wastes are those that carry both hazardous and radioactive components (EPA#2, 2013).
Basel Convention’s list of Y1 to Y18 features the wastes that need to be controlled because of their hazardous characteristics. These wastes include clinical wastes coming from the health care centers, medical clinics and hospitals, wastes generated during the production and preparation of pharmaceutical products, pharmaceutical wastes such as medicines and drugs, wastes containing cyanides, waste oils or water, emulsions, wastes from the production, formulation and use of dyes, inks, paints, varnish, resins, glues, organic solvents, photographic chemicals and processing materials, and residuals after industrial waste disposal operation (UNEP, 2011).
Characteristics of Waste
Despite the differences in the definition and classifications of waste, some of the key characteristics on the basis of which hazardous wastes are identified across all the countries include the following:
Toxicity: Toxic wastes are fatal and harmful when inhaled, ingested or absorbed through skin. The toxic effect may lead to chronic disease, including cancer (UNEP, 2011). Examples include any waste containing lead or mercury, spent cyanide solutions, many household cleaners, wood killers, and waste pesticides (EPA #2, 2005).
Corrosivity: Corrosive wastes are substances like acids or alkalis which through chemical action may cause severe damage when coming in contact with a living tissue or, if leaked, may corrode metal containers and destroy goods (UNEP, 2011).
Ignitability or Flammability: Ignitable or flammable wastes are those that are combustible and can spark fires under certain conditions. Examples include oils, gasoline, paints, lacquers, and varnishes (UNEP, 2011).
Reactivity: Reactive wastes are those that may cause an explosion, toxic fumes, vapors or gases when compressed, heated or mixed with water. For example, ammonia and chlorine bleach are reactive and may create toxic gas when in contact with each other. Other examples of reactive wastes include explosives, peroxide solutions, hypochlorite solutions and lithium-sulphur batteries (EPA #2, 2005).
Eco-toxicity: Eco-toxic wastes are those substances which, if released, may cause potential harm to the environment or to other species by making toxic effects upon the biotic systems (UNEP, 2011). Examples include oils, detergents, plastics and heavy metals.
Impact of Hazardous Waste
As per the EPA, when a small amount of hazardous substance is released into the environment, it does not pose any danger and threat to the living beings or the environment, but the same may cause injury or death to plants, animals and human beings, if a large amount of hazardous chemicals is released at a time, or a small amount is released multiple times at the same place, or the substance does not get diluted, or the substance is extremely toxic such as arsenic (EPA #3, 2014).
Municipal Waste and Its Impact on Environment and Health
Water Pollution. Waste management through landfill causes immense threat to the environment and human health. Landfills are used for the dumping grounds of municipal, industrial and hospital wastes, which include pathogenic and infectious materials, batteries, paints, used oil, acids, asbestos, pesticides and pharmaceuticals. Rain, snow, hail and other precipitation enter landfills and mix with the landfill contents, including the above mentioned hazardous components. If the hazardous waste is soluble in water, then it gets dissolved and swept away with water wherever the water flows, but if it is non-soluble in water, then it remains intact or travels suspended in water. This contaminated water called leachate passes through the layers of various trashes and may enter the environment if remains unhindered (Ramke, 2009). Since the wastewater treatment facilities cannot completely clean the leachate, it may also enter the water cycle.
Air Pollution. Besides leachate, landfill also causes polluting emissions and other adverse effects, such as landfill gas, bad odour, noise, windblown litter and dust, and turns into a breeding ground for vermin and insects. The landfill gas emissions are highly obnoxious containing carbon dioxide, methane, hazardous air pollutants (HAPs), volatile organic compounds (VOCs), and odorous compounds that may cause harm to the environment and human beings (EPA #4, 2014). Methane is an inflammable gas and may cause an explosion in a range of concentration from 5% to 15%. It also promotes global warming by contributing to the greenhouse gases. Carbon dioxide affects the respiratory system of human beings, and the presence of more than 5% carbon dioxide in the air may cause vertigo or headache, over 8% of which are fatal (Ramke, 2009).
Both methane and C02 in landfill gas are highly toxic for the vegetation of the landfill area and the nearby areas. The subsurface migration of the landfill gas may cause fire both on the landfill property or any private property near the landfill site. The emission of VOCs can cause smog or ozone formation at the ground level, leading to respiratory problems in humans and stunted growth of vegetation. Exposure to HAP may also contribute to a variety of health problems, including the damage of the central nervous system, respiratory irritation, and cancers (EPA #4, 2014).
Impact on Human Health. Studies show that individuals living nearby the landfill sites have the presence of high levels of heavy metals and organic compounds in their blood streams. A team of researchers conducted a study on 373 hazardous waste sites in Indonesia, India and the Philippines came up with the finding that about 8.6 million people living nearby those landfill sites are exposed to the risk of illnesses caused by the exposure to asbestos, hexavalent chromium, lead, and other hazardous materials. Among the people who are at risk, the exposures to the hazardous components may cause a loss of about 829,000 years of good health owing to disability, disease, and early deaths (Wayman, 2013). Lead and hexavalent chromium, both carcinogens, account for over 99% of the lost healthy years. Several studies have found a correlation between living close to landfill sites and health-related effects such as congenital malformations and various types of cancers like childhood leukemia, bladder cancer, stomach cancer, prostate cancer, kidney cancer, and liver cancer (Gouveia, 2010).
Industrial Waste and Its Impact on Environment and Health
Municipal wastes are less toxic and harmful for the environment, and with proper waste disposal techniques, their adverse effects can be reduced significantly. However, industrial wastes are often highly toxic and hazardous. Industry is the main source of hazardous waste. Even among different industries, metal production, petroleum refineries, chemical manufacturing and metal fabrication account for 90% of the hazardous waste from industries (DEFRA, 2010).
Chemical Waste. Some of the most common hazardous chemical wastes are halogenated solvents, wastewater from the production of herbicide, commercial chemical products like benzene (used in drug manufacturing), detergents, dyes, lubricants, vinyl chloride and pesticides. These chemicals have severe health impact on human beings and also on other animals. For example, methylene chloride, a hazardous waste generated from many industries, is a known carcinogen. Trichloroethylene is commonly used chemical in analgesics and also used in large quantities as industrial solvents. Small quantities of trichloroethylene are not bad for health, but like arsenic if it is consumed over a long period of time, it can damage liver, lungs and the central nervous system (European Commission, 2011). The main problem with trichloroethylene is that it is easily soluble in water and not easily separable. The levels of this chemical in some of the groundwater in the USA have been found to be alarming.
Electronic Waste. As electronic products are becoming more and more popular, more electronic and metallic wastes are entering the environment. Some heavy metals like cadmium, copper, lead and nickel are the most common hazardous waste of this industry. Lead can not only severely affect the central nervous system, but also can create learning disabilities in children. If cadmium enters in large quantity in the human body, then it can severely damage the kidney functions (LA City, 2007).
Agricultural Chemicals. Pesticides are one of the most common forms of chemical waste. Pesticides like malathion, DDT are hazardous chemicals manufactured for killing insects that threaten agricultural crops. However, their manufacturing process often produces additional hazardous materials. Furthermore, the disposal and cleaning of these chemicals are not always of high standards, and hence, they enter into the groundwater and the food chain and remains in the air. Over time, pesticides enter the human body through the air (inhalation), water and food chain (MDHSS, 2014). These hazardous chemicals designed for killing harmful bacteria or insects kill the plants and insects that are good for the environment in many cases. These pesticides and insecticides, if consumed even in small quantity over a long period of time, can damage almost all the internal organs of a human being like liver, kidney and intestine.
Other sources of Hazardous wastes and Its Impact on Environment and Health
Apart from the municipal and industrial sources, other sources of hazardous waste include military bases, mines, dry cleaners, auto garages, scientific labs, photo developers and many other types of small businesses. Unlike industrial wastes where a few types of hazardous wastes are produced or disposed in the environment, small businesses generate many types of hazardous wastes. For example, the chemicals used in developing photos, dry-cleaning and auto garages are completely different, and each of them is hazardous. Also small businesses often lack the proper disposable process for hazardous materials, and this poses greater amount of threat to the environment and human health (European Commission, 2011). For example, a study conducted in the 1990s shows that the presence of hazardous materials and radioactive materials in the ground water under military bases have been found to be pretty higher than the normal in the USA (Hamilton, 2003). Gold mining industry often releases a large quantity of mercury, which, if increased in the water level, can severely damage the health of human beings, river fishes and even many plants. If high quantities of mercury are consumed, then it may cause birth defects and kidney failures. Mining industry also uses acids and arsenic to clean metals. These acids and arsenic end up in the ground water table. These increased levels of acid in the ground water can severely damage the local ecological system.
Conclusion
As we are becoming more and more civilized, our demand for different industrial products are on the rise. The industrial output of the world is not only at all-time high, but it is increasing at a very high rate. Higher levels of output mean high levels of consumption and production and disposal of higher levels of waste and byproducts, many of which are hazardous. Hazardous materials come from everywhere. Industry is the main source of hazardous chemicals, but hazardous chemicals are also generated directly or indirectly through many other sources. Hazardous chemicals, metals, acids and pesticides can have severe impact on human health and the environment. It can destroy or change the ecology of a place, or it can cause diseases like cancer, liver dysfunction, central nervous system failure, and renal failures. It is difficult to eliminate the production of hazardous chemicals, but we should be more vigilant in the way we dispose the hazardous materials to minimize the impact on human health and the environment.
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