CHARACTERISTICS OF HAZARDOUS WASTES

 CHARACTERISTICS OF HAZARDOUS WASTES 

The Environmental Protection Agency of America (EPA) defines the characteristics of hazardous waste as: 

 1.IGNITABILITY: The waste that explodes with the application of fire, electricity spark, or any source of heat; wastes with high ignitable potential or which burn vigorously and persistently. Such waste has a flash point of less than 600C. Examples of these types of wastes are :- solvent washes, waste oil, alcohols, aldehydes, paint wastes, petroleum wastes, cleaning solvents, etc. 

2.CORROSIVITY: It is the ability of the waste to cause skin and mucosal membrane damage, burns and erosions and dissolve or corrode metallic surfaces. Such wastes have pH value of 2.512.5 at normal room temperatures (250 C). The corrosion rate for material damage is at 0.625 meters per year at 550 C.  Examples: acid sludge, battery acid wastes, caustic wastewater, alkaline cleaning wastes, rust remover waste, etc.

3.REACTIVITY: Reactivity refers to the tendency of a substance to undergo a chemical reaction, often rapidly and violently, under certain conditions. Reactive wastes are unstable and can cause dangerous situations, such as explosions, when mixed with water, exposed to heat, or under pressure.
          Here are some key points about reactivity:  

• Unstable Substances: Reactive wastes can be unstable and may react spontaneously, causing explosions or releasing toxic gases. 
• Water-Reactive: Some substances react violently when they come into contact with water, producing potentially explosive hydrogen gas. 
• Air-Reactive: Certain wastes can react with air or oxygen, leading to combustion or explosion. 
• Pressure-Sensitive: Reactive materials may also react under pressure or when subjected to shock or friction. 
• Incompatible Chemicals: Mixing reactive wastes with incompatible substances, such as acids with bases, can lead to violent reactions. Due to these dangers, reactive wastes require careful handling, storage, and disposal to prevent harm to human health and the environment. 

4.TOXICITY: Toxicity is the potential of a substance to cause harm to living organisms through chemical reactions or other processes. Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Metals have the capacity to produce long term effects like carcinogenicity, mutagenicity, teratogenicity. Toxicity can affect a whole organism, such as an animal, bacterium, or plant, as well as a substructure of the organism, such as a cell (cytotoxicity) or an organ such as the liver (hepatotoxicity). The following guideline can be used for determining whether acute and chronic toxicity may occur: if a waste contains an amount greater than ten times its standard in drinking water, or a hundred times more than in its standard in drinking water, or a hundred times more than in its standard for water used for recreational purposes. Measurement: The toxicity of a substance is often measured by its LD50, which is the dose required to kill half the members of a tested population after a specified test duration. The lower the LD50 value, the more toxic the substance. 

Types of Toxicity: 

• Acute Toxicity: This occurs when harmful effects happen after a single exposure to a substance. Effects are often immediate or occur within 14 days of exposure. 
•  Chronic Toxicity: Results from long-term exposure to a substance and the effects can take months or years to appear. 
•  Routes of Exposure: 
• Inhalation: Breathing in toxic fumes, vapors, or particles. 
• Ingestion: Consuming contaminated food, water, or other substances. 
• Absorption: Absorbing substances through the skin. Environmental Impact: Toxic waste can leach into soil and water sources, causing widespread environmental contamination. It can affect ecosystems, wildlife, and human populations, especially if it enters the food chain. 
• Regulations: Due to the potential risks, toxic waste is strictly regulated. Proper labeling, handling, and disposal procedures are required to minimize exposure and prevent contamination. 

5.INFECTIVITY: Infectivity refers to the ability of a pathogen, such as a virus, bacterium, fungus to enter, survive, and multiply in a host organism.  

• Host Invasion: Infectivity involves the pathogen’s capability to invade and establish itself in the host. This includes overcoming the host’s immune defenses and finding a suitable environment for replication. 
• Transmission: A pathogen’s infectivity is also related to its mode of transmission, which can be through direct contact, airborne particles, bodily fluids, contaminated surfaces, or vectors like mosquitoes. 
• Reproduction Rate: The reproduction rate, or R0 (basic reproduction number), is a measure of infectivity. It represents the average number of people one infected person will pass the pathogen to in a population with no immunity. 
• Disease Spread: High infectivity means a pathogen can spread rapidly through a population, potentially leading to outbreaks or epidemics if not controlled. 
• Factors Affecting Infectivity: Various factors can influence a pathogen’s infectivity, including genetic makeup, environmental conditions, and the presence of other diseases. 

6.RADIOACTIVITY :Waste containing radioactive elements. Such wastes are mainly from biomedical training and research institutes. Waste may include radioactive elements of uranium, molybdenum, cobalt, iodine. 

7.BIOACCUMULATION EFFECT : Bioaccumulation is the process by which certain substances, such as pesticides, heavy metals, or other chemicals, build up in an organism’s body over time. This occurs when the organism absorbs the substance at a rate faster than it can be metabolized or excreted. Examples: polychlorinated biphenyls (PCB), dioxin.