Classifying Hazmat Mixtures (On the Dark Side)
For potentially toxic materials, LD50 is the measurement that determines whether or not the material meets US DOT’s definition of a Division 6.1 hazmat. Often, the LD50 of a given chemical will be found on the chemical’s Safety Data Sheet (SDS). LD stands for “lethal dose,” and 50 represents 50% of a group of rats. LD50 is a measure of the dosage it takes to kill half of the rats. Simply put, the more toxic the chemical, the lower the LD50.
Classifying Toxicity—Pure Substances vs. Mixtures
When you classify a pure substance, the process is straightforward—you compare the SDS LD50 data of your material to the packing group assignment table at 49 CFR 173.133 and choose the corresponding packing group. Sodium cyanide, for example, has an oral LD50 of 5 mg/kg, making it a Division 6.1, PG I. Cadmium oxide has an oral LD50 of 72 mg/kg, so it is classified as a 6.1, PG III. But what if someone is shipping a hazmat mixture with different percentages of each component, and the components each have a unique LD50? How can the shipper determine the overall LD50 of the mixture? Let’s try an example.
Classifying Toxic Hazmat Mixtures on the Dark Side
Darth Vader needs your help! The leader of the Empire must ship some very dangerous hazmat across the galaxy (using the 49 CFR hazmat regulations, of course). Since he is a caring, concerned citizen (the guy has kids, after all), he wants to make sure his material is properly classified. He wants to ship a solid mixture that contains 40% skywalkerium, 30% soloium, 20% Binksium, and 10% other (non-hazmat).
|Material||Oral LD50||6.1 PG|
Vader isn’t sure how to classify his mixture. He thinks the mixture is most likely a 6.1 poison because 90% of its total composition are poisonous materials. Still, he has questions.
- Should he call it a PG III because its largest component is a PG III?
- Should he call it a PG I because the Lion instructor from class said something about choosing the most severe packing group in certain situations?
- Why does Jar Jar Binks get an element named after him? No one even likes Jar Jar Binks.
Luckily for Darth Vader’s conscience, hazmat shippers can use math to calculate overall LD50 of a toxic hazmat mixture instead of testing it on rats.
According to 49 CFR 173.132(c)(3), “If reliable, accurate data [for oral LD50 of a mixture] is not available, apply the formula:
In this LD50 formula:
- C = the % concentration of constituents A, B, …Z in the mixture
- T = the oral LD50 values of constituents A, B, …Z
- TM = the oral LD50 value of the mixture
When we plug the numbers of Darth Vader’s mixture into the formula, it looks like this:
The math works out as follows:
0.4 + 0.6 + 4.0 = 100/TM
5.0 = 100/TM
5.0 x TM = 100
TM = 20mg/kg
So, the oral LD50 of the mixture is 20 mg/kg, which makes it a Division 6.1, PG II hazardous material.
This useful formula can be applied to any potentially toxic mixture for which there is not already LD50 data, regardless of how many toxic constituents it contains.
Don't Miss These June Hazmat Workshops!
Build the skills and confidence to offer hazmat shipments in full compliance with US and international regulations. Meet 49 CFR, IATA, and IMO hazmat training requirements when the Complete Multimodal Hazmat Shipper Workshops come to your area.
Need training now? Convenient, interactive online courses at Lion.com let you fulfill critical training requirements without taking time away from work. Stop and start as needed to fit your work schedule, and benefit from support 7 days a week so you can complete training when it fits your schedule.
Tags: hazmat shipping
Very good. I have always appreciated the way Lion Tech develops, presents and provides training and materials.
The instructor was great, explaining complex topics in terms that were easily understandable and answering questions clearly and thoroughly.
Lion Technology workshops are amazing!! You always learn so much, and the instructors are fantastic.
The instructor was excellent. They knew all of the material without having to read from a notepad or computer.
Lion's online training is more comprehensive, has better slides, and is a superior training experience than what I would get from other trainers.
District Environmental Manager
Lion is easily and consistently the best option for compliance training. I've learned new information from every instructor I've had.
Lion was very responsive to my initial questions and the website was user friendly.
Supply Chain Director
Lion courses always set the bar for content, reference, and practical application. Membership and access to the experts is an added bonus.
John Brown, CSP
Director of Safety & Env Affairs
Having the tutorial buttons for additional information was extremely beneficial.
Lion's information is very thorough and accurate. Presenter was very good.
Download Our Latest Whitepaper
What to do before, during, and after a RCRA hazardous waste inspection to defend your site from rising State and Federal penalties.