What Physical Properties Drive Hazard Classifications?

chemical properties

When authoring Safety Data Sheets (SDS), there are several components that inform hazard classification. While aspects such as ingredients of a chemical or mixture, stability, and reactivity matter, more than 90% of the information on SDSs is based on physical properties.

This is because ingredients may lose their hazardous properties when they’re mixed with other ingredients. What matters, then, is not why a substance is hazardous, but the fact that it is hazardous in the first place. Tracking the safety information of every ingredient in a mixture can lead to over-classification, so the better method is a top-down approach from a hazard perspective based on a mixture’s physical properties.

Below, we’ll take a closer look at the physical and chemical properties of SDSs and how they drive hazard classification.

Physical and Chemical Properties of SDS

Section 9 of an SDS covers the substance or mixture’s physical and chemical properties. It covers a comprehensive list of properties, like melting point, boiling point, flash point, and more. Some of these properties are more intuitive than others, but they’re all equally important.

There’s a lot to cover in Section 9, with the minimum required information including:

  • Physical appearance (color, physical state, etc.)
  • Odor and odor threshold
  • pH level
  • Melting and freezing points
  • Boiling point and range
  • Flashpoint
  • Rate of evaporation
  • Flammability
  • Flammability/explosive upper and lower limits
  • Vapor pressure and density
  • Solubility
  • Auto-ignition temperature
  • Decomposition temperature
  • Viscosity
  • Partition coefficient

Not every SDS will contain all of these data points, as they may not be relevant or available. If this is the case, any missing data should be noted in the SDS with something as simple as a “not determined” label.

This also isn’t an exhaustive list of all the physical properties that should be mentioned. If other properties, like its dust deflagration index, are relevant, they must be included as well.

How Physical Properties Drive Hazard Classification

Hazard over-classification is mistakenly believed to have lower risks and costs associated with it than under-classification. That’s not the case— over-classification errors result in lost sales, lost markets, extensive compliance, shipping, equipment, and training costs, and incorrect occupational risk assessments.

In reality, both over- and under-classification should be avoided at all costs, with correct and accurate classification as the goal.

The easiest way to slip into over-classification is by classifying ingredients first rather than driving the classification with physical properties. By considering physical properties such as density, appearance, odor, and water solubility, you can then determine which class of hazard any particular substance or mixture falls under. This is a much better approach than figuring out how all of the various ingredients interact with each other to determine classification and leads to more consistent documents as well as improved safety.

Top-Down Approach to SDS Authoring

Having access to an SDS authoring system that can categorize products based on physical states and unique hazard combinations can make all the difference, turning what can be a tedious, complicated task into a streamlined process with minimal user input required.

GSM understands that the compliance process is often time-consuming and unnecessarily complex, which is why we offer our TotalSDS solution, an SDS authoring and management system that can reduce authoring time by 80% and keep all hazard classifications and regulatory data up to date.

Get in touch with our team today to learn more about our SDS compliance solutions that can keep your classifications accurate, free up your time, and save you money.