So here we find our complication. Grass clippings being the primary culprit as I think, for the most part, we would assume any lawn that is having the clippings collected is a lawn being treated at least with fertilizer.
At the same time, I don't use "organic" compost. Compost, amazingly, I find to be almost an object of religious contemplation. One needs to position their beliefs in a field of many possibilities. To me, any pesticide or herbicide residues would be broken down by the heat and biological intensity in the composting process. Therefore, my biggest concerns are what is happening in the compost and what its bacterial or fungal composition is.
"Why is that most important?"
Landscape designer and Proprietor of Buffalo Horticulture