Available Now: 2023 Schedule of Hazmat & RCRA Training

How DOT and OSHA Regulate Corrosive Materials

Posted on 1/21/2019 by Joel Gregier, CDGP

Safety professionals know better than most that the safety regulations created by agencies like US DOT and OSHA often don’t line up neatly. They may overlap in some areas, but diverge in others. 

Today, we’re talking about corrosives—and specifically, how the Department of Transportation (DOT) defines them in the 49 CFR Hazardous Materials Regulations (HMR) versus how the Occupational Safety and Health Administration (OSHA) defines them under its Hazard Communication Standard (HCS).

When you know how and why your materials are regulated by US DOT and OSHA, you are more prepared to make informed decisions about how to train personnel who encounter these materials and protect them on the job.

How US DOT Regulates Corrosives (Hazardous Materials Regulations) 

The DOT lumps all corrosive materials into one single hazard class: Hazard Class 8 Corrosives. There are two main ways to have a Class 8 material:
  • Materials that cause full thickness destruction of skin within 4 hours of exposure
  • Materials that corrode through steel or aluminum at least 6.25 mm (0.25 in.) a year at a test temperature of 55°C (130°F)
If you do have a Class 8 hazardous material, you will need to further classify the material by assigning a packing group to it, which tells you the relative severity of the hazard. The hazmat packing groups for corrosives are as follows:
  • Packing Group I (high hazard) = completely destroys skin ≤ 3 minutes of exposure time (within a 60-minute observation period)
  • Packing Group II (moderate hazard) = completely destroys skin > 3 minutes but ≤ 60 minutes of exposure time (within a 14-day observation period)
  • Packing Group III (low hazard) = completely destroys skin > 60 minutes but ≤ 4 hours of exposure time (within a 14-day observation period)
  • Packing Group III (low hazard) = corrodes steel or aluminum at least 0.25 in. per year

Ship hazardous materials? Join Lion for Complete Multimodal Hazmat Shipper Training and get up to date on the latest 49 CFR, IATA DGR, and IMDG Code regulations you must know to classify, package, mark, label, load, unload, and document hazmat/dangerous goods shipments of any class.

How OSHA Regulates Corrosives (Hazard Communication Standard) 

OSHA’s HazCom Standard uses the Globally Harmonized System (or GHS) to define hazardous chemicals. Under GHS, OSHA identifies three hazard classes for corrosives:
  • Skin corrosion/irritation
  • Serious eye damage/irritation
  • Corrosive to metals

Under OSHA regulations, a material may be assigned to multiple classes of corrosivity. These classifications do overlap a bit with the DOT definitions above, but there are few key differences.

For the “skin corrosion/irritation” hazard class, the big difference for GHS is that it includes irritants. GHS also does not use packing groups. Instead, it uses hazard categories to indicate relative severity.

For skin corrosives/irritants, these are defined as:
  • Category 1 = Causes full thickness destruction of skin within 4 hours of exposure time, (which matches the DOT Corrosive definition)
  • Category 2 = Skin irritants

Within Category 1 skin corrosives, GHS does have subclassifications (which align exactly with the DOT packing groups from above). They are:
  • Category 1A = same criteria as PG I = completely destroys skin ≤ 3 minutes of exposure time (within a 60-minute observation period)
  • Category 1B = same criteria as PG II = completely destroys skin > 3 minutes but ≤ 60 minutes of exposure time (within a 14-day observation period)
  • Category 1C = same criteria as PG III = completely destroys skin > 60 minutes but ≤ 4 hours of exposure time (within a 14-day observation period) 

The “serious eye damage/irritation” hazard class is something that does not have an equivalent in the DOT regulations (although many things that are corrosive to the eyes would also be a skin corrosive). This hazard class is broken up into two hazard categories:
  • Category 1 = causes irreversible effects on the eye
  • Category 2 = causes reversible eye irritation
For the “corrosive to metals” hazard class, the good news is that OSHA's criteria are identical to US DOT's metals PG III criteria (anything that corrodes steel or aluminum at 0.25 in. per year). There is only a single category for things that are corrosive to metal, so everything here would simply be Category 1.

If you would like to see more specific defining criteria, the full definitions can be found as follows:
  • DOT Corrosives = 49 CFR 173.136 and 137
  • GHS Skin corrosion/irritation = 29 CFR 1910.1200, Appendix A.2
  • GHS Serious eye damage/irritation = 29 CFR 1910.1200, Appendix A.3
  • GHS Corrosive to metals = 29 CFR 1910.1200, Appendix B.16

Hazmat Safety and OSHA HazCom Training

packaging-bottle-of-chemicals.JPGUse these new Lion.com online courses to prepare workers to safely handle, package, and ship corrosive chemicals in your workplace. The courses are designed to cover both DOT and OSHA safety training requirements and are available for a variety of materials:

HazCom: Corrosives
HazCom: Flammables and Combustibles
HazCom: Compressed Gases
HazCom: Poisons/Toxics




Tags: corrosives, GHS, hazard communication, Hazmat regulations, osha

Find a Post

Compliance Archives

Lion - Quotes

Energetic/enthusiastic! Made training enjoyable, understandable and fun!

Amanda Walsh

Hazardous Waste Professional

My experience with Lion training, both online and in the classroom, is that they are far better organized and provide a better sequential explanation of the material.

Robert Roose

Manager, Dangerous Goods Transportation

The training was impressive. I am not a fan of online training but this was put together very well. I would recommend Lion to others.

Donnie James

Quality Manager

Lion is at the top of the industry in compliance training. Course content and structure are updated frequently to make annual re-training enjoyable. I like that Lion has experts that I can contact for 1 year after the training.

Caroline Froning

Plant Chemist

The instructor was great, explaining complex topics in terms that were easily understandable and answering questions clearly and thoroughly.

Brittany Holm

Lab Supervisor

I have been to other training companies, but Lion’s material is much better and easier to understand.

Mark Abell

Regional Manager

We have a very busy work schedule and using Lion enables us to take the course at our own time. It makes it easy for me to schedule my employees' training.

Timothy Mertes

Hazmat Shipping Professional

This was the 1st instructor that has made the topic actually enjoyable and easy to follow and understand. Far better than the "other" training providers our company has attended!

Lori Hardy

Process & Resource Administrator

The instructor made the class very enjoyable and catered to the needs of our group.

Sarah Baker


You blew the doors off the competition!

Stephen Bieschke

Facilities Manager

Download Our Latest Whitepaper

Ace hazmat inspections. Protect personnel. Defend against civil and criminal penalties. How? See the self-audit "best practices" for hazardous materials shippers.

Latest Whitepaper

By submitting your phone number, you agree to receive recurring marketing and training text messages. Consent to receive text messages is not required for any purchases. Text STOP at any time to cancel. Message and data rates may apply. View our Terms & Conditions and Privacy Policy.