Jonathan Kent: Are you okay?
Clark Kent: Can I answer that in about five years?
Jonathan Kent: Yeah.
Clark Kent: Dad I'm glad you and mom are the ones that found me.
Jonathan Kent: We didn't find you, Clark, you found us.
Chloe Sullivan: I call it 'The Wall of Weird.' It's every strange, bizarre, and unexplained event that's happened in Smallville since the meteor shower. That's when it all began - when the town went schizo.
Clark Kent: Why didn't you tell me about this?
Chloe Sullivan: Do you tell me everything that happens in your life? We all keep secrets, Clark.
Clark Kent: I'd give anything to be normal.
Answer: The kryptonite only creates mutations when it reacts with the environment and an individual. Remember, the FDA and several environmental groups did check out Smallville after the meteor shower, but found no danger in the rocks. Obviously they're not always emitting mutating rays, or all the flora and fauna of the surrounding area would be horribly mutated.
Phoenix