The toxicity of a substance is generally judged by a property called LD50 or Median Lethal Dose. LD50 is the mass of a substance that would kill 50% of the population in g/Kg. It is often calculated in rats or mice and then applied to humans, so there is therefore some ambiguity and variation in the accuracy of the values. Nevertheless, it is the best assessment of toxicity we have.
Here are some examples of LD50s (in g/Kg)...
Table Salt, 3
Vitamin C, 11.9
Capsaicin (the hot stuff in chillis), 0.0472
Which brings us to chocolate.
Chocolate contains a chemical called theobromine that accounts for its toxicity, Due to the theobromine content chocolate's LD50 (in humans) is 77g/Kg. Effectively that means that 6Kg of chocolate is enough to kill 50% of the population of people weighing 12 Stone.
To put it seasonally, that is approximately 20 average easter eggs or 60 bags of mini eggs or 300 creme eggs.
Now if you think that is disappointingly low, think of your dog. The LD50 for chocolate in dogs is about 26g/Kg. This means that 1kg of chocolate is enough to wipe out a pretty large dog and considerable less is needed to cause it some serious problems. Dogs can't metabolise the theobromine as well as humans so it can easily build up in their system. If you are worried that your dog has been at your choccies then the symptoms of theobromine poisoning in dogs are nausea, vomiting, diarrhea, and increased urination progressing to cardiac arrhythmias, epileptic seizures, internal bleeding, heart attacks and finally, death
So over Easter, take it easy with the eggs but make sure you eat them before the dog gets them. It might feel selfish at the time but you are doing them a favour in the long run.
