Are Esbits Really Non-Toxic?

Are the true esbit squares non-toxic? I have come across different "opinions" searching the web. Is the square itself poisonous? Is the soot that I will wipe off the pots poisonous? and finally, can I keep an esbit cooker stove inside my pot/cup?

In reality, they are so cheap, I should just try one; but I was curious and I don't live anywhere near a store.

Thanks

Estit is made from hexamine which is also used to treat urinary tract problems.
I've used it for fuel for many years without problem.
I store the stove and a few tabs in my pot.

Here's a safety data sheet:
http://zenstoves.net/MSDS/MSDSEsbit.pdf