The downstream dangers of your perfume

Every day, those chemicals wash down the drain. While they are not themselves poisonous, they may affect biological processes in unexpected ways. Now, Stanford University biologists have the mussels to prove it.

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Welcome to the new science of ecotoxicology in which scientists try to understand how the synthetic chemicals we're pouring into our environment affect the way earthly life goes about its business.

Recent research about musk fragrances and mussels illustrates this point. When gills from live mussels were exposed to water with low concentrations of six commercial musks, they were not poisoned, point out postdoctoral fellow Till Luckenbach and Prof. David Epel of Stanford. That was expected.

But after two hours, the researchers washed the gills and put them in musk-free water that also contained a red dye. Cells in the gill tissue took up the dye. That was not expected.

Those cells have a mechanism to detect a foreign substance, such as the dye, and keep it out. That worked for cells not exposed to the musk in the first place. Cells that had been exposed lost this natural defense.

That finding has a disturbing global implication, notes the California Sea Grant program, which provided part of the funding for the study. Cells in many animal species, including humans, use the same protective mechanism to ward off foreign substances.

These musks, used to improve the smell of everything from detergents and soap to air fresheners and shampoo, are pouring into our environment. So are other synthetic fragrances.

Sewage treatment does not remove them. They build up in human tissue as well as in fish and invertebrates such as mussels. An unexpected question has been raised about a possible health risk that now should be investigated.

Laboratory research that leads to wider study is a hallmark of ecotoxicology. Scientists wouldn't know what to look for in the field without it.

Yet, "it is a virtual certainty that other effects are occurring in the field that we are presently overlooking in the lab," note the editors of Environmental Science & Technology, an American Chemical Society journal, which devoted a special issue to this new science. "How can all biodiversity be protected from the myriad of chemicals they are now exposed to, when ... we do not even know what is there?"

Japan has already banned the most common of these chemical compounds, musk xylene, and Germany has put into effect a voluntary ban on the stuff. Elsewhere, including the United States, musk xylene is still heavily used, except in products applied orally, such as lipstick.

Developing nations struggling to build their economies sometimes criticize such research as a rich country's luxury. The journal editors reply that the international effort to build up that research is vital to everyone on the planet "if we are to protect our living heritage from the cocktail of chemicals present in all environments."