The marketing meme, is that "certified potato sets" are free of various viral diseases, well, at least 95% free.... And in many jurisdictions, certified potato sets are inspected for diseases during the growing season, and/or tested for diseases before being sold. I suspect that many potato producers grow for the grocery stores using certified potato sets, so they might only be one year away from certified "virus-free" origins. They might have picked up some viruses, but if they had picked up too many, the farmers wouldn't have many potatoes to
sell. I have planted a lot of grocery store potatoes, and they have grown great for me.
Supposing that we take all the toxic gick contained in a non-organic potato set, and transfer it 100% into the new tubers, without any decomposition during the growing season. That might create around a hundred fold dilution of the toxicity. A more realistic scenario, is that the toxic gick gets spread across the whole plant, including the non-harvested stems and
roots, and it gets diluted into the soil as the seed tuber rots away, and the toxic gick gets decomposed by the plant, microbes, sunlight, and weather. So the actual dilution might be closer to 10,000 times. I don't know what your tolerance for toxic gick is, but that's good
enough for me.