Antibacterial Agent Found to Be an Endocrine Disruptor at Low Levels

(Beyond Pesticides, November 2, 2006)

In a new study in the journal Aquatic Toxicology, Canadian researchers find that at environmentally-relevant levels, the anti-bacterial agent triclosan interferes with the thyroid hormone in frogs, affecting the timing of metamorphosis in tadpoles. This study is the first demonstration of low-level impacts of triclosan on thyroid hormone function. The study raises further questions about human and environmental health risks from triclosan.

The study, entitled “The Bactericidal Agent Triclosan Modulates Thyroid Hormone-Associated Gene Expression and Disrupts Postembryonic Anuran Development,” shows that exposure to as little as 0.15 micrograms/L triclosan causes an earlier metamorphosis from tadpole to frog than normal, with effects on the tadpole brain and tail.

Results of the study indicate that low levels of triclosan can potentially affect the human thyroid gland. The thyroid plays a role in development, body temperature and metabolism.

“Frogs serve as a very sensitive sentinel species for chemicals that can actually disrupt thyroid hormone action,” said University of Victoria molecular biologist Caren Helbing, Ph.D., one of the authors of study. “Triclosan at levels measured in our waterways can actually affect how thyroid hormones works in frogs.”

The chemical triclosan, marketed widely to protect children from germs, is found in hundreds of products, including antibacterial soaps, deodorants, toothpastes, cosmetics, fabrics and plastics. Research shows that triclosan is no more effective than washing with regular soap and water, and the ubiquitous nature of the chemical is leading to antibacterial resistance problems.

“For most things, regular soap is just fine. In terms of children’s products, they shouldn’t have triclosan in them at all,” Dr. Helbing said in an interview with the Victoria Sun.

“When you ask a qualified microbiologist, they’ll tell you that it’s being overdone and there’s probably a greater chance of creating bacterial resistance than preventing problems,” said Joe Schwarcz, Ph.D., director of McGill University’s Office for Science and Society. “Washing with soap and water is enough, except in a hospital environment… You don’t want to use a jackhammer to kill an ant when stepping on it will do.”

“The reason why the triclosan story is interesting is it’s so pervasive – it’s in so many products. Even (though) the risk (of ill effects) is small, the exposure is too large,” says Dr. Schwarcz.

In fact, triclosan is used so commonly that is has made its way into the human body. It has been found in the umbilical cord blood of infants and in the breast milk of mothers.

In March, the Canadian Pediatric Society called for parents to stop buying antibacterial products, and instead use traditional soap and water to wash toys, hands or household items. This past August, an Illinois County asked EPA to cut the widespread use of antibacterial agents. The American Medical Association and Association for Professionals in Infection Control have said there’s no evidence that antibacterial soaps prevent infections in homes. Additionally, on October 20, 2005, at a meeting of the Nonprescription Drugs Advisory Committee, which advises FDA, the committee voted 11-1 that antibacterial soaps and washes were no more effective than regular soap and water in fighting infections both work equally as well. Shortly after, Beyond Pesticides, along with 14 other public health and environmental advocacy groups, petitioned FDA to ban triclosan for all non-medical uses. As of yet, the agency has failed to respond to the petition.

The widespread use of triclosan has led to contamination of the nation’s waterways. A 2006 study by researchers at the Johns Hopkins Bloomberg School of Public Health finds that after people flush antibacterial products down the drain, about 75 percent of triclocarban and triclosan compounds survive treatment at sewage plants. Most of that ends up in waterways and sludge spread on agricultural fields, and may end up on produce.

TAKE ACTION: When used in hospitals and other health care settings, or for persons with weakened immune systems, triclosan and its analog, triclocarban, represent important health care and sanitary tools. Outside of these settings, the use of these antibacterial ingredients is unnecessary, and the constant exposure to them becomes a health and environmental hazard. The best solution to preventing infections is good old, regular soap and water. Make sure you read all labels when buying soaps and other toiletry products, including cosmetics, to ensure that triclosan and triclocarban are not included. Also be on the lookout for Microban and Irgasan, which are other names for triclosan.