Q. Less than one year ago, the Occupational Safety and Health Administration (OSHA) amended the Hazard Communication Standard (HAZCOM) to harmonize with the Globally Harmonized System of Chemical Classification and Labeling (GHS). HAZCOM is one of two major programs in the United States that classifies a large universe of chemical hazards. The other major system is the Hazardous Material Regulations (HMR) promulgated and enforced by the Department of Transportation (DOT). How do OSHA’s new GHS classifications compare with the DOT’s hazmat classification system?
A. While the U.S. Department of Transportation and the Occupational Safety and Health Administration both regulate hazardous chemicals, they have very different priorities. These priorities lead to some differences in which chemicals they regulate.
The DOT regulates the safe and secure transportation of hazardous material (hazmat) in commerce. The Hazardous Material Regulations (HMR) exist to protect transporters (truck drivers, rail workers, air crews, and mariners), passengers, emergency responders, and the general public from the consequences of an incident or accident involving the sudden uncontrolled release of hazmat during the cycle of transportation. In contrast, OSHA regulates the safety and health of workplaces. The Hazard Communication Standard exists to protect workers in a workplace from the consequences of both sudden and chronic exposures to hazardous chemicals. This means that while both agencies regulate immediate hazards to safety (explosives, flammables, poison gases, corrosives, etc.), only OSHA will be concerned with the hazards of long-term exposure (i.e., carcinogens, mutagens).
What’s Similar?
Both the HMR and GHS require shippers/manufacturers to identify hazardous materials, assign those materials to a classification, and communicate those hazards to persons who could be exposed. The HMR and GHS use very similar criteria to classify “physical hazards.” For instance, both the HMR and GHS have classifications for flammable or combustible liquids. Under the HMR, the class of flammable and combustible liquids includes all liquids with a minimum flash point (closed-cup) less than 200°F [49 CFR 173.120(b)(1)]. Under GHS, the upper limit for flammable liquids is a flash point of 199.4°F [29 CFR 1910.1200, Appendix B.6.1].
What’s Different?
As stated above, both the DOT and GHS assign hazard classes to hazardous chemicals. A small difference, however, is that the DOT divides these hazards into one of nine numbered hazard classes (e.g., flammable liquids are “Class 3″), while the GHS just names them (a flammable liquid is just a “flammable liquid”).
Another aspect that is similar but not exactly analogous is that both the DOT and GHS rules require shippers/manufacturers to further classify their hazard classes by determining the “severity” of the hazard. The DOT denotes this, for most classes, by assigning “packing groups,” while the GHS uses “hazard categories.” Often, these packing groups and hazard categories align; however, there are times when they do not. A good example of harmony between the systems is the severity determination for flammable liquids, summarized below:
| Flash Point (FP/Boiling Point (BP)* | HMR Flammable Liquid Classification | GHS Flammable Liquid Classification |
| FP < 23ºC, BP ≤ 35ºC | Packing Group I | Hazard Category 1 |
| FP < 23°C, BP > 35°C | Packing Group II | Hazard Category 2 |
| FP ≥ 23°C and ≤ 60°C | Packing Group III | Hazard Category 3 |
| FP > 60°C and ≤ 93°C | Combustible hazard | Hazard Category 4 |
*Due to varying conversion factors between Celsius and Fahrenheit, there are slight variations (less than 1 degree) between the HMR and GHS classification criteria. These variances are rounded away in this presentation. [49 CFR 173.120 and 29 CFR 1910.1200 Appendix B.6.1]
Of course, not every hazard class lines up as nicely as flammable liquids.
Another big difference between DOT and GHS classification is that the GHS system regulates many “health” hazards that the DOT does not. Many of the health hazards are regulated by OSHA since the hazards arise from chronic exposure to chemicals and everyday workplace hazards. These hazards are not significant when in transportation, so they are not regulated by the DOT.
Some examples of health hazards that are regulated under GHS but not under DOT include:
- Respiratory or skin sensitization,
- Germ cell mutagenicity,
- Carcinogenicity generally,
- Reproductive toxicity (teratogenicity), and
- Specific organ toxicity. [29 CFR 1910.1200, Appendix A]
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