Hazardous waste poses threats to public health or the environment. It can be liquid, solid, sludge, or contained gas, originating from diverse sources like industrial processes or discarded commercial products. Understanding its nature and identification is important for proper management and preventing harm.
What Makes Waste Hazardous?
Hazardous wastes share common properties, known as characteristics. These include ignitability, corrosivity, reactivity, and toxicity, each indicating a distinct type of hazard. If a waste exhibits even one of these properties, it falls under hazardous waste regulations, guiding its management to mitigate risks.
Ignitable wastes can readily create fires. This category includes liquids with a flash point below 60 degrees Celsius (140 degrees Fahrenheit), which is the lowest temperature at which fumes above the waste can ignite. Solids that are spontaneously combustible, ignitable compressed gases, and oxidizers are also classified here. Examples include waste oils, used solvents, gasoline, and alcohol-based products.
Corrosive wastes are acids or bases capable of dissolving metals or causing severe burns upon contact with living tissue. Aqueous wastes are considered corrosive if they have a pH less than or equal to 2 or greater than or equal to 12.5. Common examples include hydrochloric acid, nitric acid, and battery acid, which can compromise containers and lead to hazardous leaks.
Reactive wastes are unstable and can undergo violent changes. They may cause explosions, generate toxic fumes, gases, or vapors when heated, compressed, or mixed with water. They can also form potentially explosive mixtures or detonate. Examples include certain lithium-sulfur batteries, explosives, and cyanide or sulfide-bearing wastes.
Toxic wastes are harmful or fatal when ingested, inhaled, or absorbed through the skin. They pose a significant concern because they can leach from waste materials and pollute groundwater, affecting drinking water supplies. Materials containing heavy metals like mercury or lead, as well as certain pesticides, are common examples of toxic waste.
The Regulatory Framework
The management of hazardous waste in the United States is primarily governed by the Resource Conservation and Recovery Act (RCRA). Enacted in 1976, RCRA provides the federal framework that controls hazardous waste from its generation to its ultimate disposal, often referred to as “cradle to grave” management. This comprehensive approach ensures that hazardous materials are tracked and managed throughout their lifecycle.
RCRA empowers the Environmental Protection Agency (EPA) to develop regulations that establish standards for hazardous waste. These regulations are based on the characteristics of hazardous waste and include lists of specific wastes. The act aims to protect human health and the environment from the dangers of improper waste disposal, and promotes waste minimization and the beneficial reuse of resources.
This regulatory structure ensures accountability for all entities involved in the hazardous waste chain, from generators to transporters and disposal facilities. The goal is to prevent contamination and ensure that hazardous waste is handled in an environmentally sound manner.
Identifying Hazardous Waste
Determining whether a waste is hazardous is an important step in its proper management, and waste generators bear the responsibility for this determination. This process often involves applying knowledge of the waste or conducting specific laboratory tests. The aim is to accurately classify the waste for safe handling and regulatory compliance.
One common laboratory method for identifying hazardous waste, particularly for toxicity, is the Toxicity Characteristic Leaching Procedure (TCLP). This test simulates the leaching of toxic substances from solid waste into the environment, mimicking conditions found in a landfill. If the concentration of certain contaminants in the leachate exceeds specified regulatory levels, the waste is classified as toxic.
Beyond characteristic properties, waste can also be identified as hazardous if it appears on specific regulatory lists published by the EPA under RCRA. These include the F-list, which covers wastes from common manufacturing and industrial processes, and the K-list, identifying wastes from specific industries. The P-list and U-list designate certain unused commercial chemical products as hazardous when discarded.