This is based upon my opinion through years of reading and experience.
First, if possible, do not purchase waxed produce... The wax is applied after cultivation... and you have to remove the wax before getting to the skin which has been sprayed with god knows what... :-P
Yes, the food is generally washed first before applying the wax... but with what? a chemical wash? Yes some are. And the food may have been chemically ripened.
If you have no other choice for your food, after you have washed it, peal off and discard the skins - as it is my understanding that the skins hold the vast majority of the remaining toxins... but then removing the skins also eliminates over 1/3 of the nutrients and many beneficial compounds found in most crop skins too... many that you cannot get from the pulp\meat.
Not that they would have done you much good anyway (depending upon the food and nutrient) having the nutrients and beneficial compounds bound to the *toxins* pretty much makes them all null and void - worthless when you eat them... as the body will not break most food compounds down into a toxic poison on purpose to get at a nutrient.
Different washes serve different purposes... some are better than others in various circumstances.
In general, just washing with clean water will remove surface residue and many unbound, free chemicals along with dust\dirt. I believe that a diluted 3% H2O2 (Hydrogen-Peroxid)
(food grade only) wash would work best on pesticides and other agrichemicals... a clay wash is right up there IMO... but these washes only wash the surface of the crop. A dilute ACV and salt water wash would work too.
No *wash* will get inside the food crop and remove all of the agrichemicals and toxins absorbed by the plant, and into the food through the water, soil, and air as they grow when alive... same as us.
How would you *detox* without blood and lymph fluids pumping through you? Same applies with our foods unfortunately... that is why it is so very important to try and purchase only organic, or something similar such as beyond organic, certified naturally grown, etc. Or, grow your own.
That said, and watching some of the posts here on flora, it is also my understanding that beneficial flora can work wonders on breaking down toxins in our bodies into compounds we can actually use (yes - believe it or not), or more easily get rid of.