Everyone knows that it’s possible to build up a strong tolerance to certain drugs with frequent use – alcohol, heroin, nicotine, etc. What about other, more lethal poisons?
Could someone become immune to arsenic, or ricin, by carefully dosing themselves with non-lethal amounts?
Could lactose intolerant people become tolerant, by consuming ever-increasing amounts of dairy products? How about peanut allergies?
Basically, I’m wondering if the scenario presented in The Princess Bride has any possible analogy to real-world poisons, or if the very idea is…umm…inconceivable.
It depends completely on the poison and on why it’s a poison.
Lactose: no, having more lactose will not reactivate lactase production on someone who’s lactose intolerant. Lactose intolerance is a normal part of the aging process for most people, our bodies slow down production of the enzyme which breaks up lactose. Giving yourself the runs will not make you younger.
Arsenic and other heavy metals: they accumulate in the body. Having small doses is akin to getting punched in the face once every day - it may not hurt as bad as getting a dozen punches all together, but it’s still Not A Good Idea nor will it make you stop getting bruises.
Organic compounds which are broken down by the body: many manage to create tolerance while killing you (alcohol is the most famous example). Others will not create tolerance (you still need the same dose to get the same effects, years after using that product) but will still put pressure on the body’s chemical equilibrium that wouldn’t exist without those compounds - when the reason they’re being used is that there was something wrong with the body in the first place, well, it becomes a cost/benefits analysis.
ETA: I’m not trying to be technical here, I’m sure other people will come up with more technical details.
It may be possible to develop a tolerance to arsenic. Immunity, no.
“To a limited extent, it is possible to build up a tolerance to certain poisonous metals. Metallothioneins are proteins produced in the body that, among other things, seem to bond to ions of dangerous elements like arsenic and cadmium and so help to minimize organ damage and other serious ill effects. While there’s no way to become immune to such poisons, chronic exposure to them may — I repeat, may — stimulate the body into upping its metallothionein output, thus allowing one to take on greater quantities of the toxic stuff before starting to get really sick.”
There was a guy named Mithridates who tried this, then (as legend would have it) found himself unable to commit suicide. The practice of trying to acquire immunity is named after him.
I can’t speak to heroin/nicotine/other drugs, but regarding alcohol, an addict develops a tolerance over time to the intoxicating effects - that is, as his addiction proceeds, it takes more and more alcohol to achieve a high. However, the important thing is that the LD[sub]50[/sub] doesn’t change. The result is that you have a guy who is drinking more and more each time in order to get drunk, trying to land his blood alcohol concentration in an increasingly narrow space between “buzzed” and “clinically dead.” If the addiction gets bad enough, that narrow space gets really narrow, and some day he screws up and drinks just a little too much, overshoots the safe zone and ends up dead.
It’s not simply legend. As I’ve observed before on this Board, herpetologist William E. Haast, founder of the Miami Serpentarium, practiced this. His blood was in demand as a treatment for snakebite where there was no available antivenin:
Haast was bitten many times by cobras and other snakes, including mamba and krait. He lost sirculation in his hands near the end of his life, and lost a finger, but ffor years he suffered no ill effects. He died last yea
A friend of mine installs control systems in dairies. Due to working with electricity in chronically wet conditions he said “I electrocute myself with monotonous regularity.” He has not yet developed an immunity. Perhaps I’ll suggest he needs to start upping his dosage to get any benefit.
