Dursban 25 (chlorpyrifos-ethyl)is an organo phosphorous compound which attacks the pest's nervous system.
When used commercially on fruit and vegetables there is a 7 day harvest interval after application.
I know that you will not be eating the grass.
However, if you use this product please make sure that you wear gloves, facemask, googles, overalls and rubber boots. No one should go onto the treated area for at least 48hours.