while I learning more about detoxification, I have two more questions. Although it is very rare in organic chemical compounds, there are such kinds of undetoxified or unbreakable chemical compounds such as DDT or Dioxin or PCB, is there any reason why these kinds of Toxin could not be detoxified by enzyme or liver (am i right? ) , are there any special chemical structures that hard to be broken by liver or enzyme. or there is no special enzymes to break or detoxify such kinds of toxin?

Seconds,(if there are alot of chemical structure that body could not break or detoxify) How could scientists know that the new chemical substances which they developed could be metabolized and broken into the parts or elements.... (what if it stay forever in the body)

last. as far as I know that all chemcial substances are not dangerous or lethal. because if the molecular structure of chemical substance is not simillar to hormone or not fittable to cell receptors, they could not block the function of cell or neuro system. (am I right? )
And then one toxin has the only one bad function to the receptors or cell? (is it possible for one toxin could do harm to several organs or cell or receptors..

P. S doctor teach me that toxin die with damaged cell together. It is very hard to understand because toxin molecure structrue could be changed by attacking cell or receptors?

Sorry to bother you again. Thank you very much.