Experts believe the overuse of anti-bacterial agents in household products such as washing-up liquids, chopping boards, binliners and kitchen utensils could lead to resistant bacteria, and make people complacent about basic hygiene.
Research today in the science journal Nature confirms these fears. It shows that E.coli, one of the most common causes of food poisoning, could develop resistance to triclosan - a common anti-bacterial agent.
A Health Which? survey, also published today, found that half of the people in Britain have bought anti-bacterial products. But one in 10 wrongly believed the products made dishes, surfaces and hands sterile, and one in six believed boards with anti-bacterial agents needed less cleaning.
An investigation by The Independent revealed manufacturers are charging a large premium for products that contain anti-bacterial agents. A standard bottle of Tesco washing up liquid costs 67p, a similar product with an anti- bacterial agent costs pounds 1.35. Sainsbury's 10 All Purpose cloths cost 49p, or pounds 1.59 with anti-bacterial protection.
"Ordinary detergents are perfectly adequate," said Janice Allen of the National Consumer Council. "If you stick to the normal hygiene rules in the kitchen then there isn't any need to use them."
Stuart Coverley of the National Federation of Consumer Groups said: "Consumers are being unnecessarily overcharged. They're being taken for a ride."
But despite the money spent on the products, official figures from the Public Health Laboratory Service show that the number of food poisoning cases has tripled in the past 10 years, with 100,000 cases reported in 1998.
The market for household anti-bacterial cleansers, first introduced 12 years ago, is the fastest-growing sector of the pounds 140m domestic surface cleaning products market. It is estimated that consumers spend more than pounds 25 million a year on these anti-bacterial products.
"We'd like to see a closer monitoring of this rapidly growing market, and hope that a new European Union directive, the Biocidal Products Directive, will deliver this," said Charlotte Gann, editor of Health Which? "But ultimately this is a whole new market we can do without."
The research published in Nature has shown that E.coli bacteria, one of the most common causes of food poisoning, could acquire resistance to triclosan's effects through a comparatively simple mutation.
"It works by inhibiting a key metabolic pathway involving a particular enzyme," said Professor David Rice of the University of Sheffield's molecular biology department.
"In that sense it is acting as an anti-biotic would. That means anti- biotic-type resistance could arise."
Widespread use since the chemical was introduced could also have led people to rely too heavily on it, he added.
"There's no doubt people are worried about getting bacterial infection, but basic hygiene procedures are often more than enough."
The Price You Pay
Product Anti-bacterial Standard %diff
Sainsbury's 10 All Purpose
cloths pounds 1.59 49p 224
up liquid pounds 1.35 67p 101
up liquid pounds 1.45 85p 70
up liquid 95p 75p 27
Handwash/soap pounds 1.49 47p 217
up liquid 89p 15p 493
4 economy soaps pounds 1.49 33p 351