Since you completely ignored the parent's valid point (many things that are in fact healthy for you can also cause cancer if overdoing, so the phrase "may cause cancer" by itself is not a valid argument), here's why your own argument has no merit whatsoever:
> Alcohol: can I live forever without drinking any alcohol. Yes, you can. Problem fixed.
> Alcohol: can I live forever without drinking any alcohol. Yes, you can. Problem fixed.
No you can't. Nobody lives foverer.