All of which will still be in the water after you boil it, and most filters small enough to fit into a PSK, even a biggish one, can't do much for. All of those and more will be in any rain water you collect, much less get into your eyes and on your skin. There is only one way to avoid the pollution we've created, and that is to live in a bubble.

I know the risks, and I know the odds. I'm willing to throw the dice- survival and evolution rely as much on pure blind luck as they do the subject's supperior mental and physical ability and training to determine if they get to contribute to the gene pool.