I had a discussion with a high school student about the effect and production of nicotine. He mentioned that nicotine is naturally produced in our brain so when the person takes to smoking, the brain stops producing its own nicotine and starts craving it from an external source. According to him, this is how nicotine addiction develops. How true is this?
The students also claimed that nicotine in cigarettes is harmless. I have already seen the answer about how toxic it is to humans, but I would love to know:
- What's the lethal dose for nicotine via ingestion (not inhaling)?
- How does nicotine compare to other toxic substances - for example, cyanide or any other known poison? Is it more toxic or less toxic?