Hazard classification

Many substances are potentially hazardous, including water, but not classified. This is because the hazard-exposure analysis concludes that the level of exposure to that substance

The purpose of hazard classification is to identify whether the intrinsic physicochemical characteristics of a product or its toxicological and ecotoxicological properties may represent a hazard (e.g. has a capacity to burn, explode, corrode, etc.) when handled or used.

Data on potential hazard is then considered with exposure, and this forms the basic approach to risk assessment. It is summarized in a simple formula:  hazard x exposure = risk. The implication is that minimizing hazard or exposure minimizes risk.

The Global Harmonized System of Classification and labelling (GHS) distinguishes 3 categories: substances, mixtures and articles

The properties of substances are tested by prescribed methods and the results are evaluated against criteria limits. It is worth noting that many substances are potentially hazardous, including water, but not classified when they are not considered a risk to health in normal use conditions.

For mixtures, calculation rules have been developed under GHS based on the composition of the product and in relation to hazard categories. This provides an alternative to the testing of mixtures and allows for prediction and estimation of the hazard properties.

Examples of the classification categories in GHS are:
  • Health hazards:
    • Acute toxicity
    • Sub-chronic toxicity
    • Reproductive and developmental toxicity
    • Chronic toxicity
    • Genotoxicity
  • Environmental hazards – aquatic :
    • Acute aquatic toxicity
    • Chronic aquatic toxicity
    • Potential for actual bioaccumulation
    • Degradation (biotic or abiotic) for organic chemicals
  • Physical hazards:
    • Flammable

Page glossary

  • Acute
  • Acute Toxicity
  • Bioaccumulation
  • Chronic
  • Chronic Toxicity
  • Classification
  • Exposure
  • GHS
  • Hazard
  • Risk
  • Risk Assessment
  • Substance
  • Toxicity