Mexico published its national implementation of the UN GHS on October 9 of 2015, as NOM-018-STPS-2015, Harmonized system for the identification and communication of hazards and risks from hazardous chemicals in the workplace (NORMA Oficial Mexicana NOM-018-STPS-2015, Sistema armonizado para la identificación y comunicación de peligros y riesgos por sustancias químicas peligrosas en los centros de trabajo).

The standard regulates the use of chemical substances and mixtures in the workplace, and makes no obligations relative to the SDSs provided by suppliers. Nonetheless the NOM offers perspective on what elements will best serve Mexican customers who must comply with the standard in the workplace.

Transition period
The NOM-018-STPS-2015 takes effect 3 years after the date of publication in the official journal, therefore on 8 October 2018.

During the transition period, it remains legal to use either the NOM-018-STPS-2000 or provisions voluntarily adopting the GHS per (PROY)NOM-018-STPS-2014 [the proposed NOM that was adopted as NOM-018-STPS-2015]. The NOM-018-STPS-2000 makes less prescriptive requirements to communicate hazards, so the GHS effectively complies with the NOM-018-STPS-2000.

Substance Listing
Mexico has no listings of substance classifications.

Classification thresholds
The NOM-018-STPS-2015 does not include any methods for the classification of mixtures. Instead, it references the NMX-R-019-SCFI-2011, harmonized system of classification and hazard communication of chemicals (Sistema armonizado de clasificación y comunicación de peligros de los productos químicos). Norma Mexicana (NMX) standards represent non-mandatory guidance.

The NMX-R-019-SCFI-2011 adopts the classification methods for mixtures as written in GHS, including both classification thresholds when the compromise classification system is described in the UN GHS Purple Book. This implies that an SDS compliant with either the OSHA/Canada thresholds for classification or those used elsewhere, such as in the EU, will meet the requirements for communication of hazards in the Mexican workplace. Note that NMX-R-019-SCFI-2011 is based on GHS Rev. 3.

Building Blocks
The NOM-018-STPS-2015 adopts all building blocks of GHS revision 5. The precedence of pictograms is written as per GHS, not including the provision adopted by OSHA that skull and crossbones suppresses exclamation mark only when the exclamation mark is related to acute toxicity hazards.

Deviations from GHS
The voluntary standard NMX-R-019-SCFI-2011 indicates that GHS pictograms must all be 100 x 100 mm red square on point frames (cf. 7.3.2). [Keep in mind that GHS is adopted in the context of workplace signage and that this is a voluntary standard.] Table B.2 of NOM-018-STPS-2015 sets minimum pictogram sizes (mandatory in the workplace) based on the distance of the observer from the sign. For distances less than 7 meters (which presumably applies for the actual container labels, with the use of storage area signage to indicate hazards of shelved or remotely stored products), B.4.1 indicates that the employer will define the pictogram dimensions in accordance with the size of the container or packaging, as long as it is readable. These sizes range from 31 to 375 mm, as measured along one side of the pictogram frame. 

Significant Variances between GHS in Mexico and United States or Canada

NOM-018-STPS-2015 adopts GHS Rev 5 so the most significant conflict is on aerosols, for which OSHA has clear guidance that the GHS elements may not be used as set out in Rev 5! Canada adopted Rev 5, but published special conditions for aerosols that match the OSHA adoption of Rev 3 classifications. The Mexican NOM and NMX do not prohibit using the gases under pressure classification together with the aerosols classification, so a compliant compromise might be to indicate the gases under pressure classification for aerosols in Mexican documents in addition to the standard aerosol classification. The NMX classification guideline are still based on GHS Rev. 3 though – if it is updated to include the GHS language indicating that aerosols do not require a Gas pictogram (GHS04) and are exempt from classification as a gas under pressure, this may create a conflict.

The Mexican NMX-R-019-SCFI-2011 standard on classification methods for mixtures is not mandatory. It describes the classification thresholds with both higher and lower available in the GHS compromise classification system. This implies that Mexico will accept either the use of the classification thresholds adopted by US OSHA or Health Canada (the lower thresholds in all cases) or those adopted in the EU and elsewhere (the higher thresholds for classification of the product per se, with lower thresholds used for communication of mixture contents in section 3 and some special labeling requirements in certain regions).

SDS format
The SDS may be written in free form, but must address the following sections. The content in sections 12-15 is not regulated by the Ministry of Labor and Social Welfare but must comply with requirements of the responsible agencies:

• SECTION 1. Identification of the dangerous chemical substance or mixture and the supplier or manufacturer
• SECTION 2. Hazards identification
• SECTION 3. Composition / information on ingredients
• SECTION 4. First aid measures
• SECTION 5. Fire-fighting measures
• SECTION 6. Measures to be taken in case of accidental spill or accidental release
• SECTION 7. Handling and storage
• SECTION 8. Exposure controls / personal protection
• SECTION 9. Physical and chemical properties
• SECTION 10. Stability and reactivity
• SECTION 11. Toxicological information
• SECTION 12. Ecological information
• SECTION 13. Information on the disposal of products
• SECTION 14. Transport information
• SECTION 15. Regulatory Information
• SECTION 16. Other information including information on the preparation and revision of safety data sheets
   

 The Mexican standard NOM-018-STPS-2015, Harmonized system for the identification and communication of hazards and risks from hazardous chemicals in the workplace (NORMA Oficial Mexicana NOM-018-STPS-2015, Sistema armonizado para la identificación y comunicación de peligros y riesgos por sustancias químicas peligrosas en los centros de trabajo) can be found in the Chemical Safety Consulting Resources.