Fire Codes and the GHS
Part 6: Corrosive solids, liquids, and gases
Part 6 in our series compares the International Fire Code (IFC) Corrosive hazard class with OSHA/GHS (Rev. 7) classifications to understand and document how they differ. Our goal in these articles is to provide the knowledge and tools necessary for code users to confidently assign the applicable fire code hazard class when the GHS hazard classes, generally available in a material’s Safety Data Sheet, are known.
Background
OSHA’s Hazard Communication (HAZCOM) Standard (29 CFR 1910.1200) prescribes the hazard classification system manufacturers are required to use to classify and label chemicals and communicate the hazards of materials in Safety Data Sheets (SDS). Appendix Table E104.2, introduced in the 2024 IFC, presents IFC hazard classes alongside those found in HAZCOM 2012, based on Revision 3 of the GHS. The much-awaited update to the HAZCOM Standard, based on Rev. 7 (2017) and some elements of Rev. 8 of the GHS, was published on May 20, 2024, and took effect on July 19, 2024. OSHA has since published its Corrections and Technical Amendments to the Final Rule, available here.
Corrosive to Metals
Some substances and mixtures chemically react with metals, leading to the deterioration or destruction of metal components through processes like oxidation or reduction. The damage is often rusting, pitting, or weakening of the metal over time, compromising the integrity of equipment, pipes, and metal surfaces.
The GHS and OSHA treat liquids and solids corrosive to metals as ‘Physical Hazards’ and classify them in one category based on the corrosion rate of steel and aluminum using the test procedure in Part III, sub-section 37.4 of the UN Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria.
In contrast, model fire and building codes don’t define materials corrosive to metals as hazardous materials. So, you can disregard this hazard class when encountering it on an SDS.
Corrosive to Skin
Surprisingly, there is no correlation between substances that are corrosive to metals and those that are corrosive to living tissue. The converse is also true. Materials that harm human skin and tissue involve chemical irritation, burns, or other biological reactions. These can include strong acids, bases, and other caustic substances that cause immediate harm upon contact with skin or tissue. The injuries may manifest as redness, blistering, or deep burns, depending on the substance and the duration of exposure, and the damage may or may not be reversible. Materials that cause skin corrosion are ‘Health Hazards’ under GHS, OSHA, and fire and building codes.
The IFC defines Corrosive as follows:
CORROSIVE. A chemical that causes visible destruction of, or irreversible alterations in, living tissue by chemical action at the point of contact. A chemical shall be considered corrosive if, when tested on the intact skin of albino rabbits by the method described in DOTn 49 CFR 173.137, such chemical destroys or changes irreversibly the structure of the tissue at the point of contact following an exposure period of 4 hours. This term does not refer to action on inanimate surfaces.
Moreover, the 2024 IFC Appendix Table E104.2 compares the IFC Corrosive definition and the GHS/OSHA definition of Corrosive to Skin (H314).
NFPA 400, Hazardous Materials Code (2025), defines Corrosive similarly and refers to the acceptable test methods in an Annex note.
DOT 49 CFR 173.137, referred to in the IFC definition, authorizes several in vivo or in vitro test methods published in the Organization for Economic Cooperation and Development’s (OECD) Guidelines for the Testing of Chemicals to determine whether a material is corrosive to the skin.
Under the GHS and OSHA, if the skin damage is irreversible, it is classified as skin corrosion. If the damage is reversible, it is considered skin irritation. Model fire codes no longer define irritants as hazardous materials; they focus solely on corrosive materials causing irreversible harm. The Comparison Table below shows when the GHS/OHSA Skin Corrosion classification translates to the IFC Corrosive hazard class.
Eye Damage
You might wonder whether a material should be classified as Corrosive under fire and building codes if it causes damage to the eyes rather than the skin. The GHS and OSHA classify materials separately based on skin corrosion and the harm they cause to the eyes. Under the GHS and OSHA, the health hazard categories, Serious Eye Damage, Category 1, and Eye Irritation, Category 2, address how harmful materials are to the eyes and define the terms as follows:
Serious eye damage refers to the production of tissue damage in the eye, or serious physical decay of vision, which is not fully reversible, occurring after exposure of the eye to a substance or mixture.
Eye irritation refers to the production of changes in the eye, which are fully reversible, occurring after the exposure of the eye to a substance or mixture.
I classify materials identified as Serious Eye Damage, Category 1 materials under the GHS and OSHA classification system as Corrosive under the IFC, and here is why. First, the first sentence of the IFC definition of Corrosive refers to ‘destruction or irreversible alteration to living tissue.’ ‘Living tissue’ includes eyes.
Sure, the OECD test methods authorized by the DOT and called out in the second sentence of the IFC definition are all skin tissue tests. However, that sentence does not necessarily preclude other accepted test methods from being used to demonstrate the destruction of living tissue.
Second, the Code intends to safeguard the public and firefighters, so minimizing exposure to materials that can cause irreversible damage to the eyes must be expected.
Lastly, the code change proposal to incorporate the GHS/OSHA hazard classes in the IFC definition of Corrosive was approved by the Fire Code Committee last year, and barring any public comment that upsets the apple cart, the 2027 IFC definition of Corrosive will read:
CORROSIVE. A substance or mixture that is categorized under the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) as either Skin Corrosion (Category 1A, 1B, or 1C) or Serious Eye Damage (Category 1). Where the GHS category is not known, the following is acceptable for classification purposes:
A chemical that causes visible destruction of, or irreversible alterations in, living tissue by chemical action at the point of contact. A chemical shall be considered corrosive if, when tested on the intact skin of albino rabbits by the method described in DOTn 49 CFR 173.137, such chemical destroys or changes irreversibly the structure of the tissue at the point of contact following an exposure period of 4 hours. This term does not refer to action on inanimate surfaces. [Proposed 2027 IFC definition]
The IFC Summary Table below illustrates how the GHS/OSHA hazard classes that affect the eye and the IFC Corrosive definition might align.
Overall, the Skin Corrosion and severe eye damage hazard classes align exceptionally well with model fire and building codes. Each class considers whether damage to living tissue is reversible.
You can access this and other code change proposals submitted to better align the IFC and IBC with the GHS and OSHA hazard classification systems here. If you haven’t already, sign up for our HazMat Halftime newsletter so we can update you on fire codes and the GHS!
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