Yes Roundup is a poison, but it is far less dangerous than what it replaced. I sprayed this stuff for weed control in orchards and vineyards in my teens and as a Forester U of T 74 , I know it was used in copious amounts by roadcrews, railways and hydro crews for weed and brush control on railway lines and hydro right of ways at that time. You can buy Roundup, without a permit for small time weed control at CTC, this stuff is banned by International Treaties.
https://www.ontario.ca/page/contact-herbicide-245-t
https://en.wikipedia.org/wiki/2,4,5-Trichlorophenoxyacetic_acid