I've heard and read many theories regarding the madness of Van Gogh.
He mouthed his brushes to improve the points, he ate paint, he drank turpentine, he had epilepsy, he had lead poisoning.....
True, the pigments he used, the colors he preferred, were highly toxic. Differing with the color, they contained lead, arsenic, cobalt, copper, manganese, cadmium sulphate, gambogic acid, singly or in combination.
At least he was not obliged to grind his own (and possibly inhale) powdered pigments, which was the custom in earlier times. Purists still do it, but with full knowledge of the chemicals, and with safer alternatives.
As far as his some aspects of his technique and palette, its also been said that absinthe to excess changes color perception, that lead poisoning can produce visual halos, blah blah and blah.
Can't we just say he was a wonderfully unique painter; lonely, poverty stricken, driven, rejected, under-appreciated probably an alcoholic, possibly in an advanced stage of syphilis and leave it at that?
The Myth Seekers won't be happy.