Yes but that is yes and no. A number of postemerge products have some pre-emerge activity but they are not considered pre-emerges. The vast majority of all (the few who don't are confused) use Prodiamine,Pendulum and Drive(product name). Besides I am talking mainly about preventing grassy weeds like crabgrass and not broadleaves.
Therefore show me the studies where the most common pre-emerges that control grassy weeds harm people,pets or the environment.If it is out there you would be the one who can find it. I know you are well respected on this forum and by me but I am saying the organic/natural world might be a little more open to at least pre-emerges that control crabgrass because that is one area the org. have no solution. I have seen organic companies come and go in the south because they can not beat the crabgrass. Well,what's the harm in including the prodiamine if it causes no harm.
After all even NOFA allows pyrethrum which comes from the chrysanthemum and thus is natural but so is snake venom. Pyrethrum is harmful to people and should not be on any organic/natural program but yet it is justified because I guess they needed Something.