Triclosan, an anti-microbial and anti-fungal agent used in making toothpaste, has been found to destroy good bacteria necessary for human health.
The chemical, which is also found in soaps, deodorants, mouth washes, kitchen utensils, cutting boards, toys, bedding, socks and rubbish bags, is readily absorbed through the skin.
It can then be absorbed into the gastrointestinal tracts, showing up in urine and breast milk.
Experiments on zebrafish showed it quickly disrupted communities of bugs in the digestive system important for human health.
Dysfunction to this ‘microbiome’ has been linked with diabetes, heart disease, arthritis and malnutrition.
Some bacteria were more susceptible tothe impact of triclosan – such as the family Enterobacteriaceae – and others were more resilient like the genus Pseudomonas.
It is not clear what the implication may be for animal or human health but it is feared compromising bacteria in the intestinal tract could contribute to the development of disease.
Zebrafish are an important animal model to help determine possible human biological impacts of the anti-microbial compound.
Professor Thomas Sharpton, of Oregon State University, said: “There’s been a legacy of concern about exposure to microbial pathogens which has led to increased use of these antimicrobial products.
“However there’s now a growing awareness of the importance of the bacteria in our gut microbiome for human health and the overuse of antibiotics that can lead to the rise of ‘superbugs.’
“There are consequences to constantly trying to kill the bacteria in the world around us – aspects we’re just beginning to understand.”
Triclosan was first used as a hospital scrub in the 1970s and now is one of the most common anti-microbials in the world.
It is an endocrine-disrupting chemical, meaning it effects hormones, and continues to be used in medical settings.
Dr Christopher Gaulke said: “Clearly there may be situations where anti-bacterial agents are needed.
“However, scientists now have evidence that intestinal bacteria may have metabolic, cardiovascular, autoimmune and neurological impacts, and concerns about overuse of these agents are valid.
“Cumulative impacts are also possible. We need to do significantly more evaluation of their effects, some of which might be dramatic and long lasting.”
The gut microbiome performs vital functions for human health by preventing colonisation with pathogens, stimulating the development of the immune system and producing micro-nutrients needed by the host.
Humans are routinely exposed to an array of chemicals, metals, preservatives, microbes and nutrients some of which may be beneficial, some innocuous and others harmful.
Part of the strength of the study is developing improved ways – through rapid screening of zebrafish – to more easily determine which compounds may be acceptable and which are toxic, said the researchers.