Wildlife needs a drugs policy

When we take medication, a proportion of it passes through our bodies unchanged and is flushed into the sewage system.

Some of the more persistent pharmaceuticals, such as antidepressants and the hormones in the contraceptive pill, evade clean-up processes; they are then pumped into streams and rivers, and also spread on to fields via sewage sludge. On top on this, manure containing veterinary drugs is deposited straight on to fields by livestock and used by farmers as fertiliser.

The effects on wildlife can be dramatic: in India, three species of vulture were almost driven extinct by eating the carcasses of livestock that had been treated with the anti-inflammatory drug diclofenac. Recent studies suggest that drugs designed for humans are entering the food chain of fish-eating species such as otters and ospreys, and can modify behaviour and physiology in creatures including snails, frogs and songbirds. For example, starlings that were fed worms containing a concentration of Prozac equivalent to that seen in wild worms showed changes in feeding behaviour and libido relative to controls.