Water

Given the floods in the American midwest this spring, one might reasonably suppose there was too much water in the world. But the BBC has said "the world's supply of water is running out. Already one person in five has no access to safe drinking water."

In this part of the world, we don't pay to much attention to what's going on in distant places, but when Los Angeles starts to worry that continued development in the city might be impossible because of insufficient water to support an expanding population, we start to listen.


There have been any number of suggestions about how to fix the problem, including recycling sewage. Not a bad idea at first blush. After all, all the water we use is recycled from somewhere.

But there are some disturbing indications that this might not be the best way to go and one of them involves the drugs we take. Legal pharmaceuticals, but a lot of them. People don't metabolise all the drugs they take, and of those parts that are metabolised, some of the metabolites are biologically active. Sewage treatments do not clean up all of these drug residues, and drug residues have been found in significant quantities all over North America, and in Europe. Drug residues in water, including estrogens, antidepressants and analgesics, have been implicated in a number of wildlife issues--poor health, a blurring of gender in individuals, reduced sperm counts, and general reproductive failure of fish and birds, and smaller, less noticeable but fundamentally more important creatures, like hydra.

The amounts of residues are very small--parts per billion--but they seem to be significant.

So let's suppose we do start using sewage, running it through improved treatment plants that make it nominally potable, and then adding it to a city's water supply. Round and round it goes, collecting a little more drug residue each time through the system. How may cycles before people start showing the effects? Will people who habitually soak in swimming pools and hot tubs be the first to go?