After reviewing case reports of nicotine intoxications and suicide attempts, the pharmacologist Bernd Mayer found that the lethal dose of nicotine in humans must be somewhere between 500-1000 mg of absorbed – not just ingested – nicotine. Given that one of the first symptoms of intoxication is vomiting, and that 70% of the remaining nicotine in the digestive tract is metabolized by the liver before it reaches other organs, absorbing that much nicotine is not easy.