I have a very informative update. I spoke with American Excelsior Company (the poly foam company). I asked about toxins and how safe the foam was. The conversation went something like this. "Is the poly foam toxic if it catches fire?" - Yes, even poly fiber is toxic when it burns and will create a bad taste if inhaled - (I explained what I was using it for and how the nicotine juice worked in a 510 cart, I was very detailed). "Are you familiar with MarineLand water filters for fish tanks?" - Yes, it is also toxic if it burns. The poly foam is a little thick or it could be used in place of the marine foam - "If I filled the poly foam with water and squeezed it out could I drink it?" -Yes, I would recommend washing it first. Like a water filter you would want to put it through a cycle to get out any debris that could be in the filter while being packaged- "So is the poly foam safe to filter liquid nicotine?" -Yes, as long as it doesnt catch fire, you don't want to breathe the fumes, same for the marine filter (blue foam).
So I guess everything we use for plugs are toxic if they burn. Thought that was nice to know. Now that I know the poly foam is safe to use as a filter as long as it doesn't burn, I will be going back to it. Its only $1.99 and it works better for me. Never leaks and supplies me with perfect juice every vape. If you try it, make sure you wash it first to remove any dust or debris.