Info on Monsanto's Glyphosate...https://www.youtube.com/watch?v=7sUNxX0OxP8
State of the Science of Gmo Foods - Health and Wellness section.
Glyphosate will stay in your soil for up to 20 years. It does not break down in the 3 years Monsanto states. You should assume anything Monsanto states on their packaging is false.
There are alternatives. Search "natural weed killer."
You could ask put the question to Moms Across America on Facebook.