So I'd like to chime in. It looks the the two primary ingredients for ZEP-o-zorb are Fuller's earth and powdered quartz.
First, Fuller's earth. This is good stuff! It's actually often used as an industrial absorbent for chemical spills (the purpose of ZEP-o-zorb), as well as in some types of cat litter. It totally makes sense why this stuff would work well for you, and I understand why you've been using it for a year. It's perfect for the task and has basically no downsides.
Now, about the powdered quartz... Chemically known as silicon dioxide. It's often refered to as silica. Silica is also good stuff! It's in concrete, it's the main component of glass, and of particular interest for your application, it's very good at absorbing volatile organic smelly stuff. Seems perfect, right?
Unfortunately, powdered quartz has a downside. When it's in a very fine powder, it produces a lot of dust. This silicon dioxide dust is incredibly harmful to your lungs. Long-term exposure to silicon dioxide dust results in silicosis, which is a really serious illness that kills tens of thousands of people every year. Inhaling that dust can also give you lung cancer, lupus, rheumatoid arthritis, or other autoimmune disorders.
I totally understand why you felt that this product was a great option! I don't doubt that it serves as an absolutely excellent cat litter. I had two kitties that took the smelliest shits, and I was always searching for ways to fix that (either through diet, litter, stress reduction, or other things). I also understand how upsetting it can be to share something with people and be met with disbelief, denial, and accusations. However, I really want to urge you to look past all of that and reconsider your use of this product. The silica dust is practically invisible and tasteless, and it had the chance to cause you many years of problems. You and your cat deserve to be healthy.