Hm, I'm not convinced this is contamination from human waste. The quantity of caffeine and painkillers a human consume should be too small. Also, the body does break caffeine and painkillers, the amount in waste shouldn't be meaningful

If diluted in the oceans I would say that it would be undectable. Cocaine is even harder, because it is not commonly consumed, it is for a group of people, but not enough for the statistics