Even "organic" ones are contaminated in some way by the chemicals in the wind, rain and underground water supplies, even if they aren't sprayed and fertilised.
We live in a very artificial world.
Buy the seeds which have probably been changed in some way.
The land used to be farmland so has probably been treated with numerous chemicals.
The water is from an underground well which all the water from the fields nearby drain into after the farmers have sprayed their crops.
The chemical spray from the nearby fields probably blows over in the wind and rain.
If we did use any fertiliser, even from the nearby horses instead of in fertiliser bags, we don't know what they have been eating in their feed.
We now have chickens so our eggs are as free range as they can be but we still have to buy layers mash to feed them on so don't really know how they treat that.