The MSDS lists three active ingredients, and another product, Bonide BK-32 has the same formulation (active ingredients and proportions).
Bonide BK-32's instruction booklet includes the following notes in various portions of the booklet:
Do not allow people (other than applicator) or pets on treatment area during application. People and pets may enter treated area after spray has dried.
If on skin or clothing
- Take off contaminated clothing
- Rinse skin immediately with plenty of water for 15-20 minutes
- Call a poison control center or doctor for treatment advice
Users should ... remove PPE (personal protective equipment) immediately after handling this product. Wash the outside of gloves before removing. As soon as possible, wash thoroughly and change into clean clothing.
All of the above suggests that this weed killer isn't safe. I expect that if you follow the instructions and wear shoes on the grass after it dries, then you won't have any problems, but I worry about children who, barefoot or not, have a lot more skin to grass contact than adults in a typical outside play period. Particularly for toddlers and infants who may not only put their skin into contact with the treated surface, but may subsequently put their hands or other objects in their mouths.
Two of the three active ingredients I've found in the more common Scott's products which have more explicit information regarding kids, pets, and cautionary statements:
Dimethylamine Salt of 2,Methyl-4 Chlorophenoxyacetic Acit 13.72 %
Kids and pets
Keep people and pets off lawn during application. Do not allow people or pets to enter treated areas until dusts have settled. Particles should stick to weed leaves for at least 24 hours after application, so it is best to limit activity from kids and pets for 24 hours after application.
Do not apply this product in a away that will contact any person or pet. Keep people and pets out of the area during application. Do not use this product for controlling weeds in vegetable gardens, flower beds, shrubs, or ornamental plants. Do not use around fruits, vegetables, or flowers.
This product does not have a suggestion for when kids and pets can access the area after application. The notes about vegetable gardens could signal some bioincompatibility with humans, or simply that it kills vegetables as though they were weeds.
I could not find a good example of the third ingredient.
This particular product is a very strong weed killing product, though, and all the uses suggest that it isn't meant for lawns and play areas, but heavy brush or spot weed treating. I'd suggest you not use it as a general application for lawn and [play area use, but only for spot treating, or heavy brush/weed areas, and excourage limited contact until a week and/or a good rainstorm later.