Tuesday, March 07, 2006

Don't read before/after/during eating

i am reading a book at lunch times called "the 13th element" by john emsley. it is on phosphorous (13th element discovered, does not have 13 protons). the section about phosphorous poisons (nerve gas, insecticides) has a table on with LD50's for some phospates marketed as pesticides. More intersting was the explanation of "LD50 (rats, oral)"

This stands for 'the lethal dose that will kill 50 per cent of rats who were given it orally' and it is measured in terms of the weight of toxin in mg, per body weight in kg. Rats make good subjects for testing because they are unable to vomit, so anything they ingest must pass through their bodies.
this made me wonder, really? i found this web page on the inability of a rat to vomit. which gives further references and such. and i think rats really can't vomit. how curious that vomiting requires such a high degree of muscle coordination.

2 comments:

~ AH ~ said...

isn't it kind of the same with mice? especially when you feed them soda or a few other things they can't vomit and it just expands in their tummies and kills them...

k2h said...

rats are so much bigger than mice, I wonder what the bio disposal fee cost comparison would be for the 2 subjects?

I wonder if he re-used the 50% of the rats that didn't die the first go around, or even if they didn't die he had to dispose of them and start with 'fresh' stock