Globally Harmonized System as a framework for communicating chemical hazards

The Globally Harmonized System (GHS) was developed to harmonize the classification and communication of chemical hazards, addressing the historical coexistence of multiple national schemes. This review summarizes the evolution of the GHS, its essential components (classification, labeling, and safety data sheets), and the main implementation challenges. The results show that standardization facilitates preventive management and trade, but its impact depends on technical consistency in classification and the availability of documentation (SDS/SDS) in the environments where it is used. The evidence also highlights that the comprehensibility of labels and pictograms is a critical determinant: although pictograms are generally highly memorable, misinterpretations can increase occupational risk, especially in contexts with educational or linguistic barriers. Additionally, potential sources of "disharmony" due to differences in data and expert judgment are identified, and strategies such as national lists of classified substances and technical guidelines are proposed. The review concludes that the GHS must be integrated with training, audits, and operational procedures to ensure effectiveness in real-world scenarios.