GHS vs. DOT: Why Classifications Don’t Always Match

The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) was designed to bring consistency to how chemicals are classified and labeled worldwide.

So why, even with GHS, do OSHA and DOT classifications still differ?

Different Purposes, Different Rules

• OSHA focuses on workplace safety—both chronic and acute hazards.
• DOT focuses on transportation safety—immediate hazards that could occur during shipment.

This means a chemical might be classified as hazardous in the workplace but not in transportation, or vice versa.

Key Differences in Scope

Example 1:

• OSHA considers a chemical hazardous if it causes eye irritation, even without other hazards.
• DOT does not regulate materials solely for eye irritation.

Example 2:

• Carcinogens, mutagens, and teratogens are covered by OSHA because they pose long-term health risks to workers.
• DOT only regulates them if they present an immediate hazard during transport.

The 2015 Confusion

When OSHA’s Hazard Communication Standard (HCS 2012) took effect, some packages displayed the GHS corrosive pictogram without the DOT corrosive label.

• Carriers familiar with DOT rules rejected these shipments.
• Shippers had to explain the difference: corrosive for workplace safety ≠ corrosive for transportation.

Even though GHS was designed to harmonize chemical hazard communication, differences remain between OSHA’s workplace-focused rules and DOT’s transportation-focused regulations. Knowing where these rules align—and where they don’t—can help you prevent confusion, shipment delays, and compliance issues. When in doubt, consult experts who understand both systems inside and out.