October 5, 2006 Source: :
http://communications.uvic.ca/releases/release.php?display=release&id=759 Household Chemicals May Pose
Human Health
Risk An
antibacterial agent used in common household items such as soaps,
toothpaste, processed food, and clothing represents a potential health risk
to human hormone action, says a new study co-authored by a University of
Victoria researcher. The study, published online this week in Aquatic Toxicology, examined the
effects of the antibacterial agent known as triclosan on the development, or
metamorphosis, of tadpoles into frogs. The study showed that when tadpoles
are exposed to levels of triclosan commonly found in the environment, frog
metamorphosis that relies on thyroid hormones was significantly disrupted. Triclosan is of particular concern to toxicologists because it is
structurally similar to thyroid hormones, which play a crucial role in early
human development. "Thyroid hormones and the mechanisms by which they affect cells are highly
conserved from frog to mammal," says Dr. Caren Helbing, a UVic molecular
biologist. "It’s highly likely that what affects frogs could affect mammals,
even humans." Triclosan is used in a wide variety of products, including clothing, food,
personal care products, and some plastics to make them more
bacteria-resistant. It is present in municipal effluents, is persistent in
the environment, and accumulates up the food chain. The study found that as little as one-millionth of a gram per litre of
triclosan interferes with thyroid hormones and their ability to direct the
genes responsible for frog metamorphosis. This is the same concentration of
triclosan found in 85 waterways tested across the U.S. in another, recent
study. Triclosan has also been detected in human breast milk, notes Helbing. "These
levels are in the general range of what we tested, so triclosan may be
having an impact on babies during a vulnerable time when thyroid hormones
are important in their development." Helbing hopes this study will spur further research into how low doses of
triclosan might be affecting human and wildlife health. "Given that there’s
already concern over the indiscriminate use of this product and the
promotion of resistant bacteria, it would seem prudent to limit its use to
those products where it’s really needed." To see a copy of the paper visit www.sciencedirect.com and click on
"Articles in Press." --30-- Media Contacts:
Dr. Caren Helbing (Biochemistry and Microbiology) at (250) 721-6146 or
chelbing@uvic.ca
Valerie Shore (UVic Communications) at (250) 721-7641 or vshore@uvic.ca
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