Handwash does more harm than good warn scientists

The US Food and Drug Administration said there is no scientific evidence anti-bacterial chemicals are any better than plain soap and water at killing germs. Photo / 123RF

Superbugs are becoming stronger thanks to anti-bacterial products used in homes and workplaces, scientists warned yesterday.

Antibiotic resistant bacteria are usually thought to be the result of over use of antibiotics.
But a new study of dust found a high association between anti-bacterial agents and bacteria which are resistant to antibiotics.

The dust was studied in a university sports building which included a pool, laundry, and offices.

It is thought that as bacteria become resistant to the use of anti-bacterial agents, this in turn increases the ability of bacteria to resist the drugs.

The authors of the paper in Environmental Science and Technology argue that: "Unlike antibiotic drugs, antimicrobials leave long-lasting residues and can accumulate in the environment.

Triclosan, a commonly used antimicrobial, can promote the development of resistance itself.'

They add that "a positive association was observed between the concentration of antimicrobials and the abundance of multiple antibiotic resistance genes".

Around 25 per cent of the bacteria found in the dust originated from human skin, the authors of the study said.

As well as triclosan, the authors led by Erica Hartmann of the university of Oregon listed other common anti-bacterial chemicals including triclocarban, and methyl-, ethyl-, propyl-, and butylparaben.

These parabens are commonly found in many cosmetics and shampoos. Triclosan is also found in some toothpastes.

They found that dust samples with higher amounts of triclosan also had higher levels of a gene that has been implicated in bacterial resistance to multiple drugs.

They said that although the median concentration of triclosan in indoor dust was small - much lower than amounts used in toothpaste, for example - the researchers say their findings demonstrate the need to further investigate the role of antimicrobials in dust in the rise of antibiotic resistance.

Some major manufacturers such as Unilever have chosen to reduce the use of triclosan and tricarban in their products.

Last week the US Food and Drug Administration banned triclosan and triclocarban after it said there is "no scientific evidence they are any better than plain soap and water" at killing germs.