Middlemen and store managers cannot possibly determine what food is safe. Don't harass them over this please. Wash food or peel it as much as possible. Virtually ALL pesticides are NOT safe. They are killing tools, and they can ALL cause you trouble is you eat them before they break down.
All pesticides have a half life, meaning that the pesticide has to break down at a fixed rate.
The common pesticides like Seven and Malathion break down rapidly and are not nearly as terrible as health food nuts claim, IF you wait as instructed to pick and eat the food after treatment. The problem is, these old standbys are losing their effect on tougher bugs which have mutated to resist older pesticides. In any case, the longer you store the food listed above, the longer it has to break down. Some of the chemicals though are not half life controlled since they have entered the soil in non-agricultural scenarios. This unknown factor cannot be measured or predicted, and storage time may not affect it at all.