Some of the widespread uses Roundup. 

Almost everyone has heard of Roundup, the world's number one weed killer. Hundreds of millions of pounds are used every year in the USA alone. Globally, the active chemical ingredient glyphosate is sold in over 750 products by numerous chemical companies. It is sprayed on sidewalks, streets, along the sides of roads, on school playgrounds and city parks. It is also sprayed on the soil of our crops fields as a burndown before planting, on 80% of the genetically modified foods which are engineered to withstand Roundup, and as a desiccant (drying agent) on non-organic crops such as sugar, wheat, barley, dried peas, and beans.

Evidence of Glyphosate being used as a drying agent on wheat and other crops above.

Glyphosate does NOT wash off ( and yet it is sprayed on food)  and is claimed to target an enzyme which is NOT found in humans or animals. They refer to the shikimate pathway, which is found in humans and animals, in our gut bacteria.

Note: the glyphosate content of this product of Roundup ( average for sale in hardware stores) is 1%. Syngenta's product Traxion is 44.9% glyphosate and is used as a burndown on the soil in which grains are planted. This is extremely toxic. Canada is the primary source of grains for the USA cereals, beer barely, and animal feed. 400 ppm of glyphosate is allowed on grains. 0.1ppb of glyphosate has been shown to destroy gut bacteria in chickens.

See the full list of allowable levels of glyphosate on our foods at:http://www.ecfr.gov/cgi-bin/text-idx?SID=195f8b224b4d7d5ab8cfff3bf0f92f68&node=se40.24.180_1364&rgn=div8