LD 50, better version mabey?

[JBoer]

http://scorpions.dimensional-rift.co.uk/LD50table.htm

stumbled across this, i know the table has been posted before but this one gives values for how much is injected aswell and as far as i know hasn't been posted.

if i calculated right, a.australis can possibly be considered more dangerous than an lq

 

[Kugellager]

This has been in the FAQ section for years.

http://www.arachnoboards.com/ab/showthread.php?t=24231

John
];')

 

[JBoer]

also according to my calculations it would take 8+ lq stings for a lethal dose:?
oh well enjoy

 

[JBoer]

This has been in the FAQ section for years.

http://www.arachnoboards.com/ab/showthread.php?t=24231

John
];')

oops. sorry, better let this one die then

 

[reverendsterlin]

oops. sorry, better let this one die then

yep I have posted my objection to LD50 before. There is an Austrailian that has a 5 point scale that is better but not too broad. will try to remember when I have more time

 

[RichardMorris]

ld 50 is a standard measurement. Sorry, but it is used in chemistry and biology and however you think scorpions should be rated (other than ld 50) is a waste of time. Its a valid scientific system.

What puzzles me is why the table you reference has all the "Methods of administration". It further muddies the meaning of ld 50 and while I have seen some of these ld 50 values before, but I don't recall seeing other reference saying it was iv, im, etc...

Here is my assumption: An IV of venom would be worse than an SC. This tables values indicate just the opposite. An IV application of scorpion venom should have a massive, nearly instant (and most likely fatal) since it will go right across the blood-brain barrier. The footnote at the bottom states that as well, but in this table, the smaller the number, the more potent it is, all the IV ld 50 values are higher than the sc values.

There is bound to be a better table on the internet. This is just bogus.

sc - this is what is going to happen.
im - typically a 2" needle is used to do this, do you think it's possible for a scorpion? If you had 3% body fat, IT'S STILL UNLIKELY
ip - impossible for a scorpion to do.
iv - extremely unlikely a scorpion can do this.

And no matter, the LQ (and is that LQQ or LQH?) is still #1.

 

[Kugellager]

There is bound to be a better table on the internet. This is just bogus.

No there aren't any better comprehensive tables with the LD50 for scorpions and there will likely never be anything much better as LD50 testing has been deemed unethical or no longer used and even banned in many places.

In regards to the method of how the venom is emplaced, these tests were almost all performed on lab mice. Scorpion venom is designed primarily to subdue prey or as a defense against predators. The most common predators being small mammals and other small vertebrates - not humans. So although these LD50 tables would be a fairly accurate gauge against mice and other small animals, they are not that good for judging how humans would be affected by scorpion venom. Unfortunately, it is all we have to go on.

I would also care to speculate that some species of scorpion might succeed at ip envenomation of a mouse or lizard - definitely impossible for a human as you stated.

This is one of the reasons that, even though they are very subjective, that people write sting reports in the "Sting Report" thread on AB. Although not scientific it does help to (to at least some small extent) give 'real world' measure of how a human may react to some of the more common scorpions kept by hobbyists.

John
];')

 

[skinheaddave]

ld 50 is a standard measurement. Sorry, but it is used in chemistry and biology and however you think scorpions should be rated (other than ld 50) is a waste of time. Its a valid scientific system.

Yes, LD50 is a standard measurement, but it is NOT the only such measurement accepted by the toxicological community. It is also important to remember that it is a statistical measure. This isn't like measuring velocity or valence or some other absolute ... it is merely an attempt to standardize what is, after all, the interaction of complex cocktails of various substances with even more complex biological systems.

What puzzles me is why the table you reference has all the "Methods of administration".

Because any toxicological study that is published without reference to the method of administration is completely useless and any figures derived from these studies without reference to protocol is equally useless. The real shame is that the method of venom extraction and purification is not also listed in the chart -- but then that is why the references on the right are there for those who actually want to look into it fully.

It further muddies the meaning of ld 50

No, it merely points out where the mud is -- or at least where a bit of the mud is coming from. If I may resort to analogy, this is like running two trials on the lethality of various ammunitions. Study 1 will be the effect of a 9mm bullet to the head of a set of victims. Study 2 will be the effect of a deer slug to the big toe of another set of victims. The report WOULD look a lot cleaner if you excluded the details ... but it would also be completely useless. And while my examples of the gun protocols is somewhat hyperbelous, the fact remains that the protocols used by laboratories in different places to evaluate LD50 has varied dramatically and that ignoring these differences leads to false (albeit neat and clean) conclusions.

all the IV ld 50 values are higher than the sc values.

Actually, I can only find two instances where the IV value is higher than all of the sc values for the same species. I can find several instances where the iv values is lower than at least one sc value. If you look through in general, you will see a wide variation in many of the species where multiple studies have been conducted. That is why you need to look at details so that you can compare apples to apples and oranges to oranges (even though, due to the limitations of the studies out there, you are often forced to compare tangarines to oranges and slap a disclaimer on your conclusions).

There is bound to be a better table on the internet. This is just bogus.

Actually, I think Oliver did a fantastic job of compiling data from numerous peer reviewed journals. I'm sure there is more data to be added and I'd ultimately have liked to see perhaps a small summary of the methodology for each cited study ... but I don't know that you would find a better table out there. That is, of course, unless you consider an unreferenced table superior because it glosses over issues of methodology.

And no matter, the LQ (and is that LQQ or LQH?) is still #1.

This is like trying to rank gold medalists at the olympics. Venom is not a particularly rankable substance. Unless you're producing a Discovery channel "top 5 deadly scorpion venoms" or something, I don't think you really need to declare a winner. As to your question regarding subspecies, read the papers regarding the source of their venom and you may get your answer.

Cheers,
Dave

 

[bjaeger]

Could someone provide a brief explanation on how to judge/read LD values?

 

[skinheaddave]

Brief, probably not, but I can try to explain it:

LD50 is the amount of a substance per unit of body weight that can be expected to kill half of any test group. In other words, if you take 100 mice, weigh each one and adminster the appropriate dosage proportional to the mouse's weight then you can expect to have 50 live mice at the end of it.

In terms of reading it, the lower the number the worse the accute toxicity of the substance. You can figure out how much it should take to give you a 50% chance of living by multiplying the figure by your weight in the appropriate units. I'm about 90kg so if substance a is 1mg/kg and substance b is 10mg/kg then it should take 90mg of substance a or 900 mg of substance b to reach the LD50 dosage. If both are delivered in a fixed dosage (a "sting" if you will) of 100mg then you can see that substance a is pretty dangerous but substance b, with the higher LD50, isn't so bad as it would require 9 "stings" to get me to the 50% survival rate point.

That's the theory, but in reality you need to apply a lot of caution when interpreting these figures. Firstly, each individual is going to be more or less succeptable to any particular substance. I've calculated above how much of a or b it will take to give me a 50% survival chance, but in reality I don't actually know. I may be extremely succeptable or almost immune to either substance. Remember that in testing, only half of the test group dies at that dosage. Some might also die at substantially lower dosages and some might live through much, much higher dosages. If you're concerned about population medicine then this sort of thing can be useful, but if you are concerned about your personal health then there are many more factors involved.

Another issue is that these experiements aren't actually caried out on humans (for obvious reasons). They are carried out on mice, rats or other human models. One issue with this is that body mass does not necessarily scale linearily. Look at alcohol tollerance. The 200lb guy is not going to be able to drink exactly twice what the 100lb guy can drink before he reaches the same level of intoxication. This issue of scaling is substantially greater when you're comparing that 200lb guy to a mouse weighing less than an ounce.

There is also the issue that we are not just giant mice, nor are mice just tiny people. Our biologies differ and so something that is particularily dangerous to some may be absolutely fine for others. Consider the funnel web spiders of Australia which are particularly toxic to primates (including us) but are comparatively harmless to many other species. For simple compounds, the differences may be easy to determine and quantify -- but for venoms (complex cocktails of various compounds) it isn't necessarily so easy to do.

There are also the issues of delivery etc. that have been touched on already here. One thing that was not elaborated on was the method of venom extraction and purification. A lot of scorpion venom is extracted using electrical shock. It has been suggested that this might result in an unnaturally strong contraction of the vesicle muscles and may expell material which would not normally be delivered in a sting. This might dilute the concentration of compounds of particular significance to toxological studies or may introduce compounds in greater concentration than would be expected in a natural sting.

I feel I'm forgetting to mention some other shortcomings of LD50 studies on the whole, but I suppose I can always tack stuff on later. The gist of the matter is that lower numbers are more dangerous but that you need to consider things a bit more carefully than just that. Still, in comparing Hadogenes to Leiurus on the charts, you can see that LD50 corresponds nicely with sting reports and medical journals in that the former is pretty harmless and the later is a nasty critter.

Cheers,
Dave

 

[bjaeger]

That was very well-written, Dave. Thanks for the extremely helpful explanation :clap:

There are also the issues of delivery etc. that have been touched on already here. One thing that was not elaborated on was the method of venom extraction and purification. A lot of scorpion venom is extracted using electrical shock. It has been suggested that this might result in an unnaturally strong contraction of the vesicle muscles and may expell material which would not normally be delivered in a sting. This might dilute the concentration of compounds of particular significance to toxological studies or may introduce compounds in greater concentration than would be expected in a natural sting.

One question of mine is, how exactly do they release their venom? Is it a muscle that kind of shoots it out whereas they can control the amount delivered? I've never really thought about it before. I'm pretty sure that if I had read books on scorpions before that I would know this one..

 

[skinheaddave]

One question of mine is, how exactly do they release their venom?

The vesicle is divided in half and there are muscles that compress each half into the outer wall. This forces the venom out through two very closely spaced holes towards the end of the stinger.

Cheers,
Dave

 

[errit]

Not sure if it is the right thread to post this but i came across these ld50 measurments. http://www.terra-animals.de/animals.php?mode=LetaleDosis&species=Scorpiones

There is also a list for spiders and snakes etc. I have the feeling that most of these figures are copied from other ld50 tables.
Even so the spider ld 50 is new to me. maybe a nice comparison.
intersting also is the low LD 50 measurement for A. robustus wich supposed to have a hight figure (as in low in toxicity to mice)
The inland taipan seems to be 10 times more toxic then L.quinquestriatus.

Am also surprised at the LD50 of mesobuthus (hottentotta) tamulus. considering its status i assumed it would be lower. possibly an indication that ld50 measurments
are not always a good representation of its true threat.

 

[JBoer]

The vesicle is divided in half and there are muscles that compress each half into the outer wall. This forces the venom out through two very closely spaced holes towards the end of the stinger.

Cheers,
Dave

that explains how some can inject different venoms, read that on the boards somewhere.. is there a list of these sp?

this thread is reinforcing how unreliable the LD50 table is, though it can be quite accurate. mabey someone somewhere has instuments that can inject tiny doses of potent venoms into human test subjects to find the average break-off point between 100% survivable and when it starts to go downhill.
obviously these subjects would have to be %100 willing and in tip-top shape but i imagine even that would skew the results, ofcourse this will never happen but just a thought.

 

[reverendsterlin]

well done Dave, I am glad you weighed in. I too have tried to explain the problem with the tables :wall: I think though we say nearly the same thing you did it better :worship:

 

[~Abyss~]

Thanks Dave and John for helping us all bettern understand Scorpion Venom and LD50.