Question

For determining the toxicity of different compounds, the concept of LD50, the lethal dose for 50% of test subjects is used. The LD50 in rats for caffeine is 192mg per 1 kg of body weight. Assuming the same LD50 for humans.For a 180-lb person, calculate the number of cups of coffee that must be ingested to provide the LD50 for caffeine if one cup is 12 fluid ounces and there is 100mg of caffeine per 6 fluid ounces of drip brewed coffee.

Answer 1

Per 1 kg ---> 192 mg

180 lb person = 81.6466 kg ( 1 lb = 0.453 kg) ------> == 15676.1472 mg of caffeine is lethal dose (LD50)

100 mg of caffeine ---> 6 fluid ounces

15676.1472 mg of caffeine ---> ?? = 15676.1472 mg x 6 fluid ounce/100 = 94056.8832/100 = 940.568832 fluid ounces

12 fluid ounces = one cup

940.568832 fluid ounces = 940.608 /12 = 78.380736 cups = 78 cups (nearly)

The number of cups of coffee that must be ingested to provide the LD50 for caffeine = 78 cups