If there was stuff that could live in beer and kill you, the human race would have died out a hell of a long time ago! If something toxic could come from our homebrewing, it wouldn't be a legal hobby!
I came across this from a pretty well known and award winning homebrewer railing against a fellow brewer (it was on one of those "color coded" brewboards where they are a little less friendly than we are.) I just cut and pasted it and stuck it in a file...here it is.
It's important to remember that one of the reasons we have beer today
(one of the oldest beverages in existence) is because it was made to be drunk in places where drinking the WATER was deadly....By boiling the wort, adding hops (which is an
antiseptic), changing the ph, and pitching yeast, you killed of any microorganism that good be harmful.....in fact the third runnings of the brewing process was fermented at an extremely low gravit 1-2% ABV, and it was called "table beer" or "Kid's Beer" this is the stuff that people drank with meals...it was their water replacement, like Iced tea or soda pop...because again the fermentation process insured that
it was safer than the water.
He talks about it here;
YouTube - Ancestral Ale: Brewing In Colonial America
So please, please, please, I can't stress this enough....
don't fear you beer!!!
If something bad could happen, then it would NOT be a legal hobby.....
Our beer is really the same thing as commercial beer...it's the exact same ingredients and process.....it's not like there are two kinds of malts and hops..ones for "real" beer and one for "homebrew"
Hopes this info helps....maybe show it to him.