A study has been done on 50 lakes across Minnesota looking for chemicals that find their way into the lakes.  The most common chemical was DEET (used in bug spray).  Followed by a plastics chemical, and then surprisingly cocaine showed up.  Sometimes the cocaine was even found in remote lakes not near a sewer run off.

Most of the chemicals that appeared in the results could be traced back to a nearby sewer run off or were fed from streams coming from communities.  However some lakes were so remote that the only way the particles could get there would be through the air.  Which now we find out that we are breathing in tiny amounts of cocaine all the time.

But, we're talking really small amounts here.  Don't worry too much about it.  This is a pretty cool story you can read more into and see what the environmental impact is.