While it’s true that if the LD50 is 200mg/kg, you’d expect roughly 50% of humans weighing about 100kg to die from it, I kind of suspect it doesn’t quite work th

While it’s true that if the LD50 is 200mg/kg, you’d expect roughly 50% of humans weighing about 100kg to die from it, I kind of suspect it doesn’t quite work that way. Dose/response relationships are frequently logarithmic, which means that after a certain point, you have to increase the dose by a lot to get just a little more effect. Also, LD50 values are always extrapolated from single dose tests on lab animals, typically rats or mice. Not only is that not how a human would end up ingesting 10+ grams of caffeine, the LD50 varies considerably from one animal to the next. For instance: > [S]ome LD50s for dichlorvos, an insecticide commonly used in household pesticide strips, are listed below:[0] > Oral LD50 (rat): 56 mg/kg > Oral LD50 (rabbit) 10 mg/kg > Oral LD50 (pigeon:): 23.7 mg/kg > Oral LD50 (rat): 56 mg/kg > Oral (mouse): 61 mg/kg > Oral (dog): 100 mg/kg > Oral (pig): 157 mg/kg As you can see, these numbers don’t seem to scale up in any intuitive way when you start crossing animal species. ——- [0]: https://www.ccohs.ca/oshanswers/chemicals/ld50.html https://www.ccohs.ca/oshanswers/chemicals/ld50.html