Personal care products like anti-bacterial soaps and cleaning agents may lead to environmental pollution and harm human health, a new study has found.
The study, conducted by the Biodesign Institute at Arizona State Univesity in the US, took the case of triclosan and triclocarban, two closely related antimicrobials.
Triclosan (TCS) has long captured the attention of toxicologists due to its structural resemblance to dioxin.
Triclocarban (TCC) has ski-rocketed in 2004 from an unknown and presumably harmless consumer product additive to one of today's top ten pharmaceuticals and personal care products most frequently found in the environment and in US drinking water resources.
Now, Biodesign Institute researcher Rolf Halden and co-workers, in a feat of environmental detective work, have traced back the active ingredients of soaps - used as long ago as the 1960s - to their current location, the shallow sediments of New York City's Jamaica Bay and the Chesapeake Bay, the largest estuary of the US.
"Our group has shown that antimicrobial ingredients used a half a century ago, by our parents and grandparents, are still present today at parts-per-million concentrations in estuarine sediments underlying the brackish waters into which New York City and Baltimore discharge their treated domestic wastewater," said Halden.
"This extreme environmental persistence by itself is a concern, and it is only amplified by recent studies that show both triclosan and triclocarban to function as endocrine disruptors in mammalian cell cultures and in animal models," he added.
Aiding in his team's research was another type of contamination: the radioactive fallout from nuclear testing conducted in the second half of the last century.
Using the known deposition history and half-lives of two radioactive isotopes, cesium-137 and beryllium-7, Halden and his collaborators Steven Chillrud, Jerry Ritchie and Richard Bopp were able to assign the approximate time at which sediments observed to contain antimicrobial residues had been deposited in the two East Coast locations.
By analyzing vertical cores of sediment deposited over time in the two sampling locations on the East Coast, they showed that TCC, and to a lesser extent, TCS, can persist in estuary sediments.
TCC was shown to be present at parts per million levels, which could represent unhealthy levels for aquatic life.
According to Halden, "The affected organisms are experiencing multi-generational, life-time exposures to our chemical follies."