Lethal DoseToxicity

Chem Catalyst

Which substance do you think is most toxic?

•Alcohol (ethanol, C2H6O3)

•Aspirin (salicylic acid, C7H6O3)

•Arsenic (III) oxide (As2O3)

Lethal Dose

• Lethal Dose: LD50 is the amount of an ingested substance that kills 50% of a test sample of an animal (usually lab rats)

Converting LD50

• But how do we translate the lethal dose for a lab rat to the lethal dose for a human??

• Using the rat data, scientists translate this to a lethal dose per kilogram of body weight.

?

Let’s Try: Aspirin

1.If the LD50 for aspirin is 200mg/kg, based on testing with lab rats, what is the calculated lethal dose for a 132 lb. (60 kg) adult?

2.Answer: 12,000 mg.

Alcohol

1.If the LD50 for alcohol is 7,060 mg/kg in rats, what is the calculated lethal dose for a 60 kg adult?

2.Answer: 423,600 mg

Alcohol Poisoning

• About 50,000 cases of alcohol poisoning are reported per year in the US.

• An estimated 4,000 of those cases resulted in death.

Arsenic

1.If the LD50 of arsenic is 15mg/kg in rag, what is the calculated lethal dose for our 60 kg person?

2.Answer: 900 mg.

Different toxic substances have different lethal doses

• Aspirin: 12,000 mg

• Alcohol: 423,600 mg

• Arsenic: 900 mg

Turn in your Journal