Triclosan has long since been no blank slate. For several years the synthetic antimicrobial substance has been regularly producing headlines. It was in 1972 that triclosan came onto the market as an additive in disinfectant hand wash lotions for hospital staff, since 1998 evidence has been mounting about its harmful effects. Nevertheless, the material has over the last twenty years increasingly found its way into many objects intended for daily use. Triclosan is present in cosmetics, toothpaste, household cleaners, detergents, sports clothing and kitchen utensils.
There are despite that already numerous indications that triclosan could be cause for serious concern for both human health and the environment: in face cleansers triclosan is thought to provide a path for the potentially pathogenic bacteria Staphylococcus aureus to be able to increasingly settle in the human nose. In cases involving surgery or a weak immune system this can increase the infection rate. In laboratory experiments triclosan enhanced the growth of breast cancer cells. Animal experiments have also shown that Triclosan can affect the function of muscles and the hormone system. This synthetic agent was detected in the blood, the urine and in the breast milk of many volunteers.
Larger liver, more cells happily dividing
A recent study involving experiments on mice provided evidence that, with long-term contact, triclosan damages the liver and could possibly favour the emergence of liver cancer. In order to examine how triclosan affects the liver, the researchers fed young mice for eight months with triclosan-containing feed, control animals received the same diet without triclosan. Next, the researchers examined the livers of the animals. The result: the livers of mice fed with triclosan were unusually large. At an intracellular level it was observed that genes that stimulate division of liver cells were active. This process could result in liver fibrosis, the researchers write. The liver fibrosis can in turn increase the risk of liver cancer. This is because, if during the course of liver fibrosis the tissue of the liver is increasingly converted to collagen, the liver function is affected, the researchers write. In order to test their assumption they gave both the triclosan-mice and control animals a carcinogenic medication. In the triclosan-mice more and larger tumours had grown than in the control animals.
Results are not simply transferable
Translating this in human terms, the corresponding dose of triclosan used in this experiment would be 0.05 mg per kg body weight. This corresponds to about one gram of toothpaste containing 0.3 percent triclosan. “Of this, the majority soon disappears down the drain”, write the researchers. The results of animal experiments do not lend themselves to being transferred 1:1 to humans. “Since triclosan is however almost ubiquitous, damage to the liver in humans cannot be excluded as a possibility”. Long-term studies will bring more clarity here, stipulate the scientists.
Long since in the food chain
In effluent water triclosan is able to be degraded to methyltriclosan,which has a much longer half-life in the environment. Methyltriclosan also has a very high accumulation potential in living organisms via the food chain, it says on the website of the German Federal Institute for Risk Assessment (BfR). In the USA triclosan occupies seventh place in the list of substances that are most often reported in America’s rivers. Triclosan is proven to be present In the body fluids of wildlife. With an annual worldwide production volume of around 1,500 tonnes this is hardly surprising.
Triclosan penetrates as far as the foetus
The good news: triclosan apparently does not accumulate in the body. “If the body is no longer exposed to the substance, triclosan is fairly quickly flushed out. Since the substance however occurs almost universally, the exposure to it is ubiquitous”, explains Dr. Rolf Halden from Arizona State University. Under his leadership a team of scientists examined the triclosan load in pregnant women and their foetuses. “We were able to detect triclosan in the urine of all pregnant women who participated in our study. Approximately half of the cord blood samples were positive as well. This means that triclosan most likely also manages to get into the foetus”, according to one scientist involved in the study, Dr. Benny Pycke.
Doctors, nurses and nursing carers at particular risk
In particular it’s hospital staff who regularly clean their hands with antibacterial wash lotions that end up accumulating a great deal of triclosan in the body. This was shown by a study of staff from two hospitals who washed their hands either using cleaning agent with a triclosan component of 0.3 per cent, or simply soap and water. The employees who regularly used triclosan-containing wash lotion had significantly more triclosan in the urine than the soap-using group.
All the same: triclosan has since 2010 in Europe not been permitted for use in food and materials that come into direct contact with food. In 2012, a German-Slovak research team placed the substance at number six among the most problematic substances in Europe. Germany’s BfR has been warning for several years about the use of the substance in detergents and textiles and the US Food and Drug Administration is currently again reviewing the risk-benefit ratio of the substance. Whether this leads to stricter guidelines remains to be seen.