PITY male fish swimming in oestrogen-laced water. As if smaller testes weren’t bad enough, some will even become “intersex” and be unable to breed, with disastrous effects on the population’s future.
The effect of continuous, low-level exposure to oestrogen from waste water on wild fish populations has never been fully explored before. Karen Kidd, an ecotoxicologist now at the Canadian Rivers Institute at the University of New Brunswick in Saint John, and colleagues tested what the hormone did to wild minnows in a 34-hectare lake in Ontario, far from directly polluted watercourses.
Kidd’s team first surveyed the minnows for two years. Then for three years they…
