Throughout England, scientists have found female egg protein in blood plasma samples of male trout living below sewage treatment plants. In 1996, U.S. researchers found effluent from sewage treatment plants in Minneapolis and Las Vegas causing the same effect in carp living downstream. Again, estrogen in waste water was the prime suspect. Pesticides and industrial chemicals that imitate natural hormones, however, have not been ruled out. Arid regions in the West are especially vulnerable to waste water contaminants, scientists said.
Many streams run almost entirely on sewage effluent during the dry season.
And many cities depend on waste water to replenish aquifers tapped for drinking water. Barber recently traced an agent called EDTAused in shampoo and food products from a sewage treatment plant in Los Angeles County to well water tapped by residents in Pico Rivera and Whittier.