(Beyond Pesticides, February 4, 2009) A new test for triclosan, developed by researchers at the U.S. Department of Agriculture‚Äôs Agricultural Research Service (ARS), could help to expedite environmental monitoring of this widely used antibacterial chemical which has been found at high concentrations in rivers and other water resources. Triclosan is linked to a range of health and environmental effects, from skin irritation, bacterial resistance and endocrine disruption, to dioxin contamination and adverse impacts on fragile aquatic ecosystems.
The new test called “magnetic particle enzyme immunoassay,” can detect triclosan at a concentration of 20 parts per trillion (ppt)-the equivalent of 1 ounce in 31 million tons. The research team at ARS evaluated the test by using it to detect triclosan and its derivative, methyl-triclosan, in river water, tap water and sewage samples from three municipal plants. They were able to detect triclosan below 20 ppt (the detection limit), indicating very low levels of triclosan in the collected samples.
ARS chemist, Weilin L. Shelver, at the ARS Animal Metabolism-Agricultural Chemicals Research Unit in Fargo, N.D., developed the new triclosan test in collaboration with Jennifer Church, Lisa Kamp and Fernando Rubio, a research team at Abraxis, Inc., of Warminster, Pa. Ms. Shelver says the test complements existing analytic methods, such as the gas chromatography-mass spectrometry (GC-MS), and is not intended to replace them, especially for routine monitoring of triclosan in a large number of water samples. The new test is faster, cheaper, and easier to use, especially for routine monitoring.
“This new technique is capable of measuring the triclosan content of a large number of water samples much faster than previous methods,” says Ms. Shelver. “We plan on expanding the assay’s use into the detection of triclosan in other environmental matrices and food.”
The researchers also tested wastewater samples. Their analysis showed that, before treatment, triclosan levels sometimes exceeded 3,000 ppt, but after treatment, those levels fell below 500 ppt. According to Shelver, the results confirmed other reports indicating that sewage plants’ purification steps removed some, but not all of the triclosan from water before it is discharged into the environment.
In the validation phase of their studies, the team compared the test results to those generated by GC-MS instrumentation, which is very sensitive but costly and requires dedicated lab space, as well as specialized training to use. In addition to correlating well with GC-MS analysis, the new test proved to be sensitive enough to distinguish triclosan from chemically similar contaminants.
Triclosan is a widely used antibacterial agent found in hundreds of consumer products, from hand soap, toothpaste and deodorant to cutting boards, socks and toys. A recent study found that triclosan alters thyroid function in male rats. Other studies have found that due to its extensive use in consumer goods, triclosan and its metabolites are present in waterways, fish, human milk, serum, urine, and foods. A U.S Geological Survey (USGS) study found that triclosan is one of the most detected chemicals in U.S. waterways and at some of the highest concentrations. Triclosan has been found to be highly toxic to different types of algae, keystone organisms for complex aquatic ecosystems. A recent U.S. Environmental Protection Agency (EPA) survey of sewage sludge found that triclosan and its cousin triclocarban were detected in sewage sludge at the highest concentrations out of 72 tested pharmaceuticals.
For more information on triclosan and its impacts on human and environmental health, visit our Antibacterial program page.
Source: Agricultural Research Service (ARS)- Agricultural Research Magazine, Spectroscopy Now