What is the least severe rating in the GHS classification system?

In the GHS (Globally Harmonized System of Classification and Labelling of Chemicals) classification system, the severity of hazards is rated on a scale that typically ranges from one to four, with one representing the most severe hazards and four indicating the least severe. Therefore, a rating of four signifies a lower level of concern regarding the potential health or environmental impacts of a chemical.

The rationale behind this rating system is to provide a standardized way to communicate hazards associated with chemical substances. A rating of four indicates that the substance poses a minimal risk, while ratings of one, two, and three represent progressively more severe hazards, necessitating more stringent handling and precautionary measures. This clear hierarchy helps in risk assessment and safe management of chemicals in various industries.