"that Dow had deliberately increased the power of AO"
So what?
It wasn't the 24-Dichlorophenoxyacetic acid or 2,4,5-Trichlorophenoxyacetic acid that caused the problem.
It was the various dioxin impurities.
And as has already been asked - what qualifications does that guy have to make that statement, and what does it mean anyway? There would be an effective dosage rate for spraying. Increasing the concentration would under many circumstances actually reduce the area covered because you'd be spraying in too concentrated a form. Basically the statement is invalid
Don't forget Dow were not the only manufacturers of 24-D/24,5-TCP
You also had Monsanto and Diamond Shamrock making large volumes, and a number of smaller companies as well. The stuff was actually developed in the UK at Rothamstead during WWII and a number of UK companies made it. I've packed down several tonnes of it into small bottles over the years, and I'm still here to tell the tale
Its clear from your comment that you know SFA about phenoxy herbicides so by mentioning them all you do is undermine what little case you may have.
For what its worth - 2,4-D is till manufactrured in the UK and is still available fro use