From Wikipedia:
> The reported half-life of glyphosate in soil varies from two to 197 days with a typical field half-life of 47 days being suggested.[56] Soil and climate conditions affect glyphosate's persistence in soil. The median half-life of glyphosate in water varies from a few days to 91 days.[56] At a site in Texas, half-life was as little as three days. A site in Iowa had a half-life of 141.9 days.[94] The glyphosate metabolite AMPA has been found in Swedish forest soils up to two years after a glyphosate application.
It has a lower half-life in water, and a lower half-life when it's warmer. I store my oats both dry and cold.
As for cancer, I don't know - but it certainly is giving everyone parkinsons.
