elcrep

Its fantastic to see someone with real scientific credentials on our side for once. Much respect to you.

Just to synthesize what you said, the key ways of removing nasties from hair are bleaching chemicals, UV light, and things that make the hair more porous(?)
I wasn't aware that washing up liquids did this. People have talked about high pH substances contributing to opening the hair cuticle (I think Jerry G suggests a sodium bicarbonate solution).

From a scientific perspective, what could you say about propylene glycol and/or products like Zydot which contain high concentrations of PG?

Once again, its great to have a chemist's opinions on these subjects. So often, detox product companies bamboozle us with spurious and contrived pieces of science, simply to make us part with our cash, rather than educating us.