Carnegie Mellon University chemists say they have discovered an environmentally friendly way to destroy harmful female sex hormones that contaminate rivers and streams and sometimes drinking water.
Estrogens enter the environment after being excreted by livestock that naturally produce these chemicals, or are flushed into sewers by the estimated 16 million American women who take birth control pills.
Until now, no practical way existed to break down these hormones in wastewater. They have been linked to developmental disorders and reproductive complications in fish and other wildlife, and could pose a threat to human health, said CMU chemist Colin Horwitz, whose findings will be presented today at a meeting of the Green Chemistry and Engineering Conference in Washington.
"These chemicals have been found in the environment at very low levels, but they are very potent," said Gerald LeBlanc, an environmental toxicologist at North Carolina State University. "The goal is to break these things down so they lose their estrogenic activity in a way that doesn't create other problems."
To do so, Horwitz and colleagues at the U.S. Department of Agriculture took advantage of a powerful catalyst invented by Terrence Collins, who directs the Institute for Green Oxidation Chemistry at CMU's Mellon College of Science.
In 2003, Collins announced his research team had discovered a new class of "green" catalysts called Fe-TAMLs, which are iron tetra- amido macrocyclic ligands.
Catalysts are substances that speed up the rate of chemical reactions but aren't consumed in the process.
Fe-TAML catalysts separate hydrogen peroxide -- a medicine cabinet staple -- into water and an oxygen atom. The oxygen atom is then free to destroy undesirable molecules and render them less toxic without producing any nasty byproducts. …