Carbon, when formed on food by charring, etc., is supposed to be carcenogenic. This may be due to the reactivity of carbon with respect to other elements when the food is mashed and smooshed and churned around by the hydrochloric acid of your stomach.
Also, small particulates can be highly carcenogenic, even if they are chemically inert, for example asbestos. That stuff is so "rock solid" it's good for very high temperature insulation, so by itself in large pieces, it's quite harmless. But if you breathe it's dust, you get lung cancer, all because of the size and shape of its small particles. This goes for anything else, too, including carbon.
Furthermore, when food, just about of any kind is cooked, there is always the potential that the heat may change something naturally not harmful into something else that might be.
But we should get all stupid about it; the watchword is moderation! We can eat just about everything cooked every which way (sometimes even not, if you like it really rare... but that poses its own different risks) but let's not overdo anything!
Years ago, there as a villiage in Northern China that had an abnormally high incidence of esophageal cancer. After doctors looked into it, it turned out that the residents had for generations traditionally eaten lots and lots of pickled vegetables... per day! And the high acid and salt, among other probable chemical transformations involved in the pickling probably irritated their throats so much that many, many people developed cancer.
I plan on using BOTH my TOS (no bloody A, B, or C) charcoal kettle and the fancy post-TNG (probably E) propane drive system, complete with thermal sensor and flux control disks tomorrow afternoon... and I'm a TOS guy. I guess that answers the original thread's question.
Topic: Grilling: Gas or Charcoal? (Read 7089 times)