Zinc toxicity may not show up in a year or a few years. It's bioaccumulative. There's a reason why a warning is placed for long term usages. Just like sweeteners, they are great on the surface, but what we don't realize is what other adverse functions it causes. In biochemistry, we know for a fact that low level of zinc helps with restorative functions. However, high concentration of zinc, combined with iron, unwanted hormonal fluctuations, and chemical exposures from other sources throughout our lives in the areas we travel to and fro, zinc, in combinations of unseen factors, play a insidious role of mRNA destruction for the concentrated areas. Kidneys, liver, glands, and even brain tissues.
Of course, no one has to listen, but do put that in the back of your mind for the time being and do a bit of published medical and biochemistry journal reading. Great sources to put you to sleep andale you go banana too.