Constitution Of An Ox

[nailit]

Is it really possible to have a high resistance to chemicals?
Ive had it said to me (more than once) that I must have the constitution of an ox. Every time that I have to have dental work done I have to have extra anesthetic. Ive drunk enough alcohol in one sitting that has killed others with alcohol poisoning, Ive overdosed in the past during periods of depression with pills that have been fatal to others and experienced nothing more than a hangover, Ive had 2 colonoscopies (with sedation) that have really hurt me and yet others who have had the same procedure have reported painless experiences.

Is it really possible that some people just have a high tolerance to chemicals?