Here is a mail I received.

Varun*, an IT professional working in Technopark, was finding himself with an upset stomach every night. While normal medical checks revealed nothing wrong in him, deeper probes revealed the reason – his stomach was collecting significant amounts of wax. And doctors identified the villian – the ordinary paper cups he used for drinking his tea at his office pantry.

Disposable paper cups have become quite popular in office pantries due to the convenience it offers. What many overlook is the fact that these paper cups are coated with a tiny layer of wax, which is essential to prevent water from seeping into the paper. When very hot liquids are pour over this cup, the wax may disintegrate and a little may come off, which will promptly be sent along with the drink into our stomachs! While our body can discard minor amounts, over the long-term, it does become a problem.

So what can be done about it? You can try to bring your own glass cups. Glass is one of the least reactive materials in the world (remember acids are stored in glass vessels, blood samples are collected in glass plates – these are for a good reason). But glass does have the problem of breaking easily, so it requires good care. Ceramic cups are probably the best bet. Of course, you can also use your ordinary stainless steel glass, but never use plastic ones – its dangers are even worse than wax!