This paper seems balanced:
http://74.125.155.132/scholar?q=cache:1MrI0c6oxtkJ:scholar.google.com/+organic+manure+%22food+poisoning%22&hl=en&as_sdt=80000000&as_ylo=2005&as_yhi=2010
Rememeber that organic agriculture was a main cause of the dust bowl of the 1930s.
It is dangerous to live in a free society where we make individual choices. I prefer to live with these dangers rather than have the government protect me.
If you have a lawn (spayed or not), you are maintaining a wildlife desert. We have chosen to develop 90% of our farm as wildlife habitat, which we can do by practicing high-intensity farming practices on 10% of the land. This seems preferable to me compared with disrupting all the land with low-intensity farming practices. The animals agree based on their numbers and diversity. They spend little time on my unsprayed lawn.
