We live in a world which is becoming more and more synthetic.

Even if we try to have natural organically grown foods, avoid synthetic detergents etc. we can't really do it.

We are constantly exposed to numerous chemicals which are foreign to our body. How we individually respond to them depends on our genetic makeup and previous environmental exposures.

Many of those substances will not cause any damage on initial exposure, but with repeat and accumulating exposures they eventually will.
There is very limited data on the effect of chronic exposure to various substances, but the limited data there is, is quite alarming.

For instance a substance which is widely used in the cosmetic industry showed no ill effects when given to lab animals in a certain dose. But, when the same dose was used for 90 days there was a significant effect on multiple organs. A recent study showed that genetically modified crop considered safe, led to serious ill effects in lab animals exposed to it for a significant period of time (previous studies were done with a very short exposure, which caused no such effects).

There are no follow up studies on humans and physicians are not trained to recognize, diagnose (or even consider) the ill effects of such environmental exposure. So, there is no way to know what they really are.

A cup of hot chocolate can potentially contain numerous substances, which can effect the immune system, mitochondrial function and numerous metabolic processes. It depends on what you made it from.