answer:@flo One can only imagine the myriad of industrial chemicals that flow into our municipal sewer systems….but it is one particularly sinister group of chemicals that is having a direct effect on plant, animal and many sources of drinking water and it is pharmaceuticals that are excreted by the hundreds of millions of us who are connected to municipal sewer systems. I don’t have time to find the links, but I have read many studies that document physiological changes of aquatic creatures mutations that have a substantial link to human hormones found in our waterways that have waste water discharged into them. Unintended consequences.