A synthetic hormone added to a remote Canadian lake at a concentration measured in just a few parts per trillion produced an ecological shock: a population of fathead minnows was pushed to the brink of collapse.
The finding came from a rare whole-lake experiment in Ontario, where researchers deliberately introduced the synthetic estrogen 17α-ethynylestradiol (EE2) into Lake 260 to understand what long-term exposure to hormone-like chemicals could do to freshwater ecosystems.
