Estrogen-mimicking pollutants can trigger gender-bending effects in wildlife. For instance, male fish exposed to such hormonally active pollutants will make vitellogenin, an egg-yolk protein that's normally fashioned only by females (SN: 1/8/94, p. 24: http://www.sciencenews.org/sn_edpik/ls_7.htm). A new study finds that once initially spurred to make vitellogenin, males don't need a steady bath of estrogen to maintain high levels of the motherly protein.
Grace H. Panter of AstraZeneca in Brixham, England, and her colleagues exposed male fathead minnows (Pimephales promelas) to up to 120 parts per trillion (ppt) estrogen in water for 3 or 6 weeks. Some fish lived in tanks continuously laced with the hormone. Other fish spent half their time in clean water, either every other day or 3 days straight of every 6.