What is the best method for determining the hazard classification of an unknown substance?

Consulting the Safety Data Sheet (SDS) is the best method for determining the hazard classification of an unknown substance because the SDS is a comprehensive resource that provides detailed information about chemical substances. It includes critical data such as the chemical's properties, hazards, safe handling practices, and emergency measures. This document is specifically designed to help workers and responders understand the risks associated with chemicals and to use them safely.

Using smell tests may pose serious danger, as inhaling hazardous fumes can lead to health risks without providing reliable information about the substance's classification. Performing water solubility tests may not accurately indicate the overall hazard classification either, as solubility could give incomplete insights into the chemical's behavior in different environments. Equipping personal detectors can certainly aid in identifying certain volatile substances or monitoring specific hazardous gases, but these devices are not comprehensive enough on their own to classify wide-ranging hazards accurately. Therefore, consulting the Safety Data Sheet stands out as the most thorough and reliable approach to assess the hazards of an unknown substance.