Adverts teach us that germs are the "enemy" and portray sparkling clean homes as the standard to aspire to. But the overuse of antibacterial cleaning sprays and soaps has raised concerns in recent years. Perhaps a little dirt doesn't hurt?
Many antibacterial products contain a chemical called triclosan. Some scientists have suggested that by using too many antibacterials at home, we are encouraging bacteria to become resistant to this chemical and mutate in to difficult-to-kill "super bugs". Researchers at Stanford University found that certain strains of bacteria such as E coli became hardier when exposed to triclosan over time.
"The results from our experiments indicate that constant exposure to triclosan can cause bacteria to tolerate it better and become more and more resistant," says the study author Clara Davis, a doctoral student.
Eric Ryan and Adam Lowry, the founders of Method (an eco-friendly cleaning products company), say they have a "zero tolerance policy" on the liberal use of antibacterials.
"Cleaning and killing are two different things," explains Ryan. "There's a very serious reason for not wanting to kill bacteria. In the past few years, more and more types of antibiotic-resistant bacteria have been appearing. There are a number of theories for why this is happening and one of them points a finger at the frequent use of certain antibacterial agents. We play it on the safe side and avoid the use of these chemicals."
Others worry that if our homes are sterile environments, children will not be exposed to many germs and, as a result, their immune systems will not develop properly and more of them will suffer from allergies. This "hygiene hypothesis" was first proposed by Dr David Strachan in the British Medical Journal.
In his paper The Hygiene Hypothesis: Are Cleanlier Lifestyles Causing More Allergies For Kids?, the allergy expert Marc McMorris from the University of Michigan concludes: "We've developed a cleanlier lifestyle and our bodies no longer need to fight germs as much as they did in the past. As a result, the immune system has shifted away from fighting infection to developing more allergic tendencies."
There is also some discussion about whether or not antibacterial products are even effective for cleaning. In 2005, a team of scientists from the University of Michigan found no evidence to suggest that antibacterial soap reduced bacteria more than plain soap.
It's worth noting, too, that common colds and flus are not caused by bacteria but by viruses that aren't killed by antibacterial products.