See the paper by Deborah W. Knapp et al., “Detection of herbicides in the urine of pet dogs following home lawn chemical application,” at Science of The Total Environment, Volumes 456–457, 1 July 2013, Pages 34-41.

No surprise: dogs in contact with lawns pick up lawn chemicals, which increase the risk of bladder cancer. And even more sinisterly, “Dogs may serve as sentinels for human exposure.”

To state the obvious: children are more sensitive to pesticides and herbicides than adults are; and children, like dogs, like to romp in grass.