Hi,
The LD50 is the dose of a given chemical product (pesticide,…) which causes the mortality of 50% of a group of test animals in a specified period. It is commonly used in bioassays assessments to measure the acute toxicity of a chemical active ingredient. The lower the LD50 value the more toxic the chemical.
There are also some other toxicity terms used such as LD01, LD90 and LD100.
You can check out this link for more details: http://www.ccohs.ca/oshanswers/chemicals/ld50.html
Cheers
Hi. I think that half-maximal effects is just easier for biochemists to understand since we deal with many half-max. constants like Kd, Km, etc.
I agree with Steingrimur Stefansson. Anyway, sometimes LC90 or MIC90 are also used in biochemistry and microbiology, as the minimal inhibition concentration to cause 90% effect. I have never heard LC30 or LC40, theoretically is possible, but 50% or 90% are more significant.
Hi,
The LD50 is the dose of a given chemical product (pesticide,…) which causes the mortality of 50% of a group of test animals in a specified period. It is commonly used in bioassays assessments to measure the acute toxicity of a chemical active ingredient. The lower the LD50 value the more toxic the chemical.
There are also some other toxicity terms used such as LD01, LD90 and LD100.
You can check out this link for more details: http://www.ccohs.ca/oshanswers/chemicals/ld50.html
Cheers
Glad to see people giving well-written, succinct, and meaningful answers to questions.
It gives you a standard level of comparison between different compounds as to which will be more toxic. In addition, it gives you a reference concentration that you should go below it, sublethal concentration to show that your effect was not due to toxicity and rather it was a true pharmacological response disregard the associated toxicity.
I guess by now you got the definition. However, as mentioned earlier, you can use LC30 or LC10 too. It depends on your application later in the study. LC50 is traditional way of estimating how toxic a substance is as by definition it is the chemical concentration/dose which causes death of 50% of population in the study. This is helpful when you are aiming for dose response curves i.e dose dependent studies or in drug dosage studies. Even if you get LC10 or LC90 it can't be helpful in that scenarios unless you need to know the effect for 10 or 90 % of population! Hope this helps.
When you have the LC50 or LD50 values you can more easily discuss whether a strain/group/population of individuals is significantly more resistant/tolerant or sensitive than the average members of that species.
(Note: Always be careful with the use of the terms tolerant & resistant, these have a different meaning; tolerant refers to a higher LC50/LD50 concentration in that subgroup of indiviuals, because of a genetic difference (e.g. mutation), while resistance refers to the basal tolerance that is normally present in all the members of the population and is not due to a genetic difference in the subpopulations of that species)
THe LD50 (lethal dose - 50%) is the dosage of a drug that is toxic or lethal causing death in at least 50% of the population of animals and is expressed as a dose like mg/kg of animal weight etc. The LC50 (Lethal Concetration - 50%) is an analogous term used to measure drug toxicity in cell cultures as a measure of drug concentration that kills 50% of the cell population in vitro and is expressed as a concentration like mg or microgram per litre or ml. The LC50 unlike the LD50 is dependent on a time frame like over 48 hours or 72 hours of cell culture. It is also limited by cell line, culture conditions, media and other factors. But scientists do use these two terms interchangeably, but for cell cultures LC50 is the right term and for animals or humans LD50 is the right dose. Of course, it is not possible to estimate LD50 for humans since the researcher might well end up for murder. hence LD50 values for humans are usually construed from its effect on mice. But some scientists confuse IC50 wtih LC50, which is completely wrong since IC50 is the concentration that inhibits a specific biological process or a specific parameter which must be defined clearly and SHOULD not be used to define lethality or toxicity.
Having an a knowledge of the LC 10 or LC 90 in addition to the LC50 of a drug, substance or toxicant gives a lower and upper limit of toxicity or drug activity where applicable.
it is particularly useful when a substance does not follow a dose response pattern i.e. where toxicity or drug activity does not necessarily increase with increasing concentrations.
LC50s can also describe aqueous concentrations used in vivo animal exposures as in zebrafish and medaka (small teleost fish models). It would not be an LD50 because you cannot be certain of the exact dose that each fish receives, especially when LD50s are reported terms of mass (mg/kg, etc).
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