I get asked fairly frequently about the use of herbicides, the residual of them, and how they affect us. The short answer: very minimal impact, if any, on humans and mammals.
Most of the products are inert within 24 hours. Herbicides we use in lawn care we use because they’re designed to work on a function a plant contains that a human or mammal does not. Broadleaf weed controls mimic the overstimulation of auxins in the plant. Humans/mammals do not have phyotohormonal pathways, therefore the material is inert to us. The risk according to the LD50 is less than that of sodium chloride (salt).
I believe in applicable cultural practices to really curb and mitigate the control of weeds naturally with your help: mowing higher in the summer during peak heat and not scalping the lawn. Denser turf creates a canopy and won’t allow weeds to take over.