See if any of the ingredients in the patches have any known carcinogens. I think any chemical has potential in some, and may depend on length of exposure, usage, even if they say it's safe, FDA approved. I used listerine mouthwash excessively for decades, and wonder about the high alcohol content, and ambersol on my back gum area for quite a while, and it contains a carcinogen to have contributed to me having tonsil cancer. A google search may help. Good luck.
