Toxicology is the study of the adverse effects of chemicals on living organisms. It is the study of symptoms, mechanisms, treatments and detection of poisoning, especially the poisoning of people. Toxicity is measured by LD50 or “lethal dose.” This means that out of a certain number of test subjects (usually rats or other rodents), 50% had died because of their contact with whatever the tested substance was. For example, parathion (which is a type of pesticide) with an LD50 of 3 mg/kg would be highly toxic. That means that half the test animals that are given 3 mg/kg body mass will be expected to die (Basic Chemistry textbook, 34). Toxicology is measured by parts per million (ppm), which equals milligrams per kilogram (mg/kg). For every kilogram of an animal’s weight, you need a corresponding weight of the material being tested.

              Mathieu Orfila is considered to be the modern father of toxicology, having given the subject its first formal treatment in 1813 in his Traité des poisons, also called Toxicologie générale. As technology progressed, testing toxicity has become more concise. However, the study of toxicology comes at a cost: an extremely large number of test subjects. Then again, they are just rats.

How to calculate toxicity:

  1. Take the weight of an animal, such as a rat
  2. Take a substance, like table sugar, and look up its toxicity in LD50
  3. For rats, it will take 29,700 milligrams per kilograms of body weight to kill a rat (all in one dose). If you have a rat that weights 3kg, it will take 29,700mg/kg * 3kg = 89,100 milligrams of table sugar, all in one dose, to kill a rat weighing 3kg

Sources: “Letter to editor…” Calculation of LD50 (Spearman-Karber) “Environment, Health and Safety Committee [EHSC]”


About Skphjlmt

We are four people: Stephen, Paul, Jin Do, and Micah!

18 responses to “Toxicology”

  1. Jose says :

    Well, definitely the most intellectual post thus far, since I actually had to stop and re-read some things to make sure I was understanding everything. Good job guys! So far, this is the only blog where I practically didn’t know anything about the subject at hand 😛 I like how you said, “they’re just rats.” I would love to observe a toxicology test. Thanks for all the info!

  2. Stefanie Tan says :

    That video was very short and to the point. I was about to close it when I saw that it only had 10 more seconds to go, so I didn’t :b I had no idea that they would use eye fluids to calculate someones toxicology. Is there something specific that they test for when collecting eye fluid?

  3. kenny says :

    i wonder how often it happens that rats and humans react differently to certain elements.

  4. Brittany McGavran says :

    I found that very interesting to read and learned a lot, and i feel sorry for all the lab rats that are used to determine the toxicology of something.

  5. Zach Armstrong says :

    this kind of did not make since to me but im glad we can find out if an element is toxic or not

  6. Michael says :

    wow that’s interesting!! that would seem like a pretty cool job to test poisons all day! I would have never guessed that there would be a science to it! I bet animal rights activists hate toxicology:P

  7. Kohl Herman says :

    this is confusing… but really cool… i am going to use this info to kill something.

  8. ajachem says :

    Jenny: I wonder if there’s more to this field than what is told in public. It does have a relation with death and possibly murder. Maybe there should be some information that should be concealed from public? Just my opinion. 🙂 Great post.

  9. Karl Geary says :

    That is quite interesting (and rather confusing). Though 3 pppm is surprisingly small for any substance to kill a creature. This actually reminds me of the mercury post by explosionsrus… what’s the toxicity of mercury?

  10. Mary Smith says :

    this is kinda confusing.. haha so now we can all calculate how much of a substance it will take to kill someone 😉

  11. Joseph says :

    this is really confusing but it’s also cool to learn some new stuff. nice guys 🙂

  12. jjemchem2 says :

    Esther: I have never knew about this at all.
    Today, Im learning too many things at once.
    But it is cool cuz I learned that we can calculated the amount of toxic we need to kill an animal/ human! 😛
    btw.. as soon as I read “rat” from this post.. Im not feeling well… (why did I read that!!) 😦

  13. jjemchem2 says :

    Janice: Pertaining to the example you provided, if the 3kg rat consumes less than 89,100mg of table sugar, it won’t die? So even if a substance is potentially toxic to a particular animal, it won’t be deadly unless the animal is given a certain amount?

    • Skphjlmt says :

      Toxicity is measured in LD50s, as stated in our post. This means that 50% of all test subjects die from a certain dose of a certain substance. So, 50% of those 3kg rats tested on died from consuming 89,100mg of table sugar. make sense? 🙂

  14. jjemchem2 says :

    I didn’t even know there was a field called toxicology. It’s really interesting that you can figure out how much toxic you need to kill an animal/person.

  15. Ben Hubert says :

    Well that sounds like a fun job. How much parathion would you have to give the hulk to kill him?

  16. oh yes, its Angela :) says :

    Woaah!! they test the eye fluid of a dead guy for levels of toxin?! wicked…yep, i’d be one of those students that pass out. ^^

  17. Alexa Challandes says :

    Um, i did not know any of this… and i guess i’m glad people figured out how to decide if something was lethally toxic…?

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