Sure, the body processes things that come into it through the digestive system and the respiratory system, and so on. But it's the nature of those chemicals coming in that are a problem as well as the fact that many of them the body has never seen before. It has never had to develop mechanisms for either breaking down persistent chemicals or for dealing with the toxic results of, say, breakdown products and so on. So sure, the body will process what comes into it, but the effects that result are what we're concerned about.
I just found that to be a bizarre statement he made. It's not useful information in terms of the concerns that exist for some of the more toxic components, especially synthetic chemicals. But of course there is lots of toxicity associated with naturally occurring substances, such as lead or mercury.