Pesticides on Edible Flowers

I bought some Pansies about three weeks ago at a local grocery store. I found a Shortbread Cookie recipe a few days later that uses edible Pansies. Most likely the Pansies I bought were treated with pesticides before they arrived to the grocery store. My question is, now that I've had the pansies for three weeks, are the pesticides still in the Pansies? I would like to use the Pansies for my cookies but not if they still contain pesticides. Please advise. Thanks!