Is Pyrethrum Spray Safe?

So I'm planning on making a batch of pyrethrum spray to rid my plant of bugs, but I'm just wondering how it will effect the plant, specifically its smokeability. How long before harvest should I stop using the pyrethrum?

If you use it regularly, like a weekly maintanance progam, stop a week before harvest. Mist the plants for a few more days. Flush a few days before harvest. VV