dickie, I'd be surprised if you came up with any evidence to suggest anything other than my postulation.

From MSDS(material safety data sheets):
Glyphosate has an LD50 of >4050mg/kg in mice. Mice, rats etc are used as trying to find toxicity levels in humans would be a bit of a problem. LD stands for lethal dose, the 50(%) for the point where half the number of specimens die in a test due to the toxicity. "Glyphosate may irritate the skin" but is "of low toxicity if swallowed"


Sprayseed, the main alternative to glyphosate for broadspectrum control, has an LD50 of 112-150mg/kg in rats and interestingly 65mg/kg in Monkeys for key ingredient paraquat. Lethal dose for a man 2-3 grams. Diquat the other key ingredient kills man with 4-6 grams.

I'll address environmental effects when I have more time.