11.   And tobacco manufacturers have never conceded publicly that nicotine is an addictive substance.

12.   Instead of using addictive substances, they binged and purged.

13.   It shows how addictive substances seduce the brain and impose themselves in place of the natural neurotransmitter dopamine, which triggers our sensation of pleasure.

14.   Like other addictive substances, marijuana appears to hijack brain circuitry that evolved to help people find their way back to a food source or sexual partner.

15.   Metadate CD, like Ritalin, Adderall and similar drugs, are what are known as Schedule II controlled substances, the most addictive substances that are still legal.

16.   News reports said crack was the most addictive substance known to man, and prisons started to fill with people who once might have gotten help instead.

17.   Smoked cocaine is probably the most addictive substance used by humankind.

18.   Such self-administration of drugs by animals has been shown to be a hallmark of addictive substances.

19.   The effects are compounded because nicotine is regarded by most scientists as a highly addictive substance, so it is repeatedly delivered to the body over time.

20.   The FDA appealed to Clinton after concluding that nicotine is an addictive substance that needs to be regulated.