Webster’s Dictionary defines corrosive
to mean…Just kidding.
When it comes to regulatory compliance, you can leave your dictionary on the shelf. Both US EPA’s RCRA hazardous waste regulations and US DOT’s Hazardous Materials Regulations (HMR) contain requirements related to corrosive
- Under RCRA, corrosive hazardous wastes are signified with the code D002.
- Under the HMR, corrosives are a Class 8 hazardous material.
The two sets of regulations define “corrosive” differently. Facilities that manage and ship hazardous wastes and/or hazardous materials must know two definitions
for “corrosive” to comply with environmental and
US EPA—RCRA Hazardous Waste Regulations
A material is a corrosive hazardous waste (D002) if:
- It is aqueous and has a pH < 2 or a pH > 12.5 (i.e., very strong acids and bases); or
- It is liquid and corrodes steel at a rate greater than ¼ inch per year.
(40 CFR 261.22)
US DOT—Hazardous Materials Regulations (HMR)
In transportation, a material is corrosive (Class 8) if:
- It is a liquid or solid that causes irreversible damage to human skin at the site of contact within 14 days after an exposure time of 4 hours; or
- It corrodes steel or aluminum at ¼ inch or more per year.
(49 CFR 173.136—137)
What’s the Difference?
EPA’s definition of a corrosive hazardous waste is based on pH levels or the waste’s corrosive effect on steel. DOT’s definition of a corrosive hazardous material does not include pH criteria—it is based strictly on the material’s corrosive effect on skin, steel, or aluminum.
There is a logical reason why US EPA and DOT maintain separate, slightly different definitions of “corrosive.” The two agencies have different goals, and their respective regulations reflect these goals.
EPA’s RCRA hazardous waste regulations aim to prevent hazardous waste from entering the environment.
To achieve this, the regulations include standards for on-site management, exclusions for recycling activities, and Land Disposal Restrictions or LDRs.
The goal of US DOT’s Hazardous Materials Regulations (HMR), on the other hand, is to ensure the material is transported safely.
DOT’s definition of corrosive considers the damage to human skin because supply chain workers may handle the package many times before it reaches its destination—during loading, transportation, storage, at a port, etc.
US DOT's definition of a Class 8 also considers the material's corrosion of steel and aluminum. Why aluminum? More than a quarter of all aluminum is used in the transportation industry. It is commonly used for the construction of cars, buses, trains, ships, and aircraft.
Is Every D002 Waste a Class 8 Hazardous Material?
A D002 (corrosive) hazardous waste with a low or high pH will most likely also meet the DOT’s criteria for a Class 8 hazardous material.
That said, some wastes with a pH between
2 and 12.5 can still harm skin. In this case, the waste would be classified as a Class 8 corrosive for transportation purposes, even though it does not fit the criteria for a D002 hazardous waste. The same is true for a waste that corrodes aluminum at ¼ inch per year, but not steel.
The DOT’s definition of a Class 8 corrosive includes physically solid materials that harm skin. The RCRA definition does not include solids. Therefore, it’s possible to have a waste that is not
a D002 corrosivity hazardous waste (because it’s not a liquid), but must be shipped as a DOT Class 8.
US EPA denied a petition
to add solid materials to the RCRA definition of corrosive in 2021.
To summarize: The criteria for classifying D002 hazardous wastes and Class 8 hazardous materials are found in two different, stand-alone sets of regulations.
Although there is some overlap, the RCRA regulations and the HMR should be considered and applied separately–RCRA for hazardous waste identification, onsite management, and subsequent treatment and the HMR for offsite transportation.
In-person RCRA Workshops Return in 2021!
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In June and July 2022, the two-day RCRA training
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EH&S professionals leave the workshop with detailed, up to date resources that make the regulations easier to read and use. Plus, receive a full year of Lion Membership for answers to on-the-job questions, access to regulations updated throughout the year, exclusive updates, and more.