MATERIALS

The CRETIB code refers to the characteristics by which waste is considered as hazardous. When exhibiting at least one of such characteristics waste is classified as hazardous. Furthermore, non-hazardous waste mixed with hazardous waste is contaminated becoming thus hazardous.

In Mexico, the NOM-052-SEMARNAT-1993 standard defines CRETIB as:

“The classification code for the characteristics exhibited by hazardous waste, referred to as corrosive, reactive, explosive, toxic, flammable, and biological- infectious.”  

The most appropriate name for such standard is CRETIB.

Countries are free to organize their laws according to their particular needs and regulatory frameworks, without contravening international agreements such as the Basel Convention.  

According to the NOM-052-SEMARNAT-2005 standard, materials may exhibit one or more characteristics defined by the CRETIB code, which stands for:

• C: Corrosive, which refers to the ability of certain compounds to dissolve another compound.
• R: Reactive, which characterizes hazardous waste that is unstable and may pose an explosion hazard in a certain stage within the waste management cycle.
• E: Explosive, which is the ability of certain chemical substances to provoke an explosive or detonating decomposition or reaction, whether alone or in the presence of a source of energy, or if heated when confined. Explosiveness should not be determined by a laboratory test, but based on the knowledge of the waste origin or composition.
• T: Toxic, which refers to the ability of certain substances to damage living tissues and the central nervous system, to provoke a serious illness or, in extreme cases, to cause death, when ingested, inhaled, or absorbed through the skin.

A) TE: ENVIRONMENTAL TOXICITY

The characteristic of a certain substance or mixture of substances that results in an ecological imbalance

B) TH: ACUTE TOXICITY

The extent to which a certain substance or mixture of substances may damage or cause death to an organism in a short period of time or by a single exposure.  

C) TT: CHRONIC TOXICITY

The property by which a certain substance or mixture of substances may have long-term detrimental effects on organisms, generally from continuous or repeated exposure, being able to result in carcinogenic, teratogenic, or mutagenic effects.

• I: Flammable, which means the extent to which a gas, liquid, or solid may ignite and the speed at which, once ignited, it may propagate its flames. The faster the ignition, the more flammable the material. Liquids are not flammable by themselves, but because their vapors are ignitable.
• B: Biological-Infectious. Biological-infectious waste contains bacteria, viruses, or other microorganisms able to infect. Such waste contains toxins produced by microorganisms able to provoke infections.

Each of such properties can be specifically tested at the laboratory under standard conditions in order to detect them on the substances under test.