Hazardous Waste: Definition, Classification (CRETIB), and Characteristics
Waste
Waste is any material discarded by its owner, having no direct use value in the process. The potential for recycling poses a challenge, as waste can also be a raw material. This global issue has various solutions. Some countries classify discarded materials as waste even if destined for recycling. This enhances environmental protection but increases administrative costs for generators and recyclers, potentially discouraging recycling. It’s recommended to consider materials as waste until processed to ensure environmental protection, especially where control infrastructure is limited.
Hazardous Waste
Hazardous waste poses a risk to public health or the environment due to its corrosivity, reactivity, explosivity, toxicity, flammability, or infectiousness. Radioactive waste, while hazardous, is typically managed by separate agencies and not included in this definition. The CRETIB code classifies hazardous waste based on these characteristics.
The General Law of Ecological Equilibrium and Environmental Protection (LGEEPA) defines hazardous materials as elements, substances, compounds, waste, or mixtures, regardless of physical state, that pose a risk to the environment, health, or natural resources due to their corrosive, reactive, explosive, toxic, flammable, or biologically infectious properties. Hazardous waste under LGEEPA refers to waste in any physical state with CRETIB characteristics that endanger the ecological balance or environment.
Corrosivity
A waste is corrosive if it meets any of these criteria:
- Watery with a pH less than or equal to 2 or greater than or equal to 12.52
- Liquid and corrodes steel at a rate greater than 6.35 mm per year at 55°C
Reactivity
A waste is reactive if it exhibits any of these properties:
- Unstable and reacts violently without detonating
- Reacts violently with water
- Generates toxic gases, fumes, or vapors in harmful quantities when mixed with water
- Contains cyanides or sulfides that release toxic gases, vapors, or fumes when reacting
- Detonates or explodes under a strong initial stimulus or heat under confinement
Explosivity
A waste is explosive if it has any of these properties:
- Forms potentially explosive mixtures with water
- Easily detonates or explodes at 25°C and 1 atm
- Manufactured for explosions or pyrotechnic effects. The EPA considers explosive waste a subset of reactive waste.
Toxicity
A waste is toxic if it can cause death, serious injury, or adverse health effects if swallowed, inhaled, or contacted with skin.
Flammability
A waste is flammable if it meets any of these criteria:
- Liquid with a flash point below 60°C (excluding aqueous solutions with less than 24% alcohol by volume)
- Non-liquid and ignites by friction, moisture absorption, or spontaneous chemical changes at 25°C and 1 atm, burning vigorously and persistently
- An oxidant that releases oxygen, stimulating combustion and intensifying fire in other materials
Biological Infectivity
A waste is infectious if it contains disease-causing microorganisms or toxins. This excludes household waste and domestic effluent treatment waste.