Women are being exposed to deadly diseases through the everyday use of common cosmetics bought over the counter, according to a new study.

The growing list of synthetic ingredients manufacturers add to their products are turning the most innocent-looking shampoos and moisturisers into cocktails of toxins that could cause cancer over years of sustained use.

In "Drop Dead Gorgeous: Protecting Yourself From The Hidden Dangers of Cosmetics," to be published in Britain next month, authors Kim Erickson and Dr Samuel S. Epstein reveal how manufacturers exploit loopholes in legislation designed to protect the public.

'These synthetic ingredients are inexpensive, stable and have a long shelf-life,' said Erickson. 'Manufacturers love them, but although the majority of products appear safe in the short run the results from long-term use could be deadly.'

The UK cosmetics industry, which employs more than 20,000 people and accounts for £4.5 billion in sales each year, is regulated under the the Department of Trade and Industry's 1996 Cosmetic Products (Safety) Regulations.

But while the regulations have approved more than 3,000 ingredients for cosmetic use in Europe, Erickson warns that many more find their way into use through loopholes, such as the caveat that allows products to contain traces of banned substances if they could not reasonably be removed during or after manufacture.

'Modern cosmetics contain a host of dubious ingredients which would be more at home in a test tube than on our faces,' said Erickson. 'Coal tar colours, phenylenediamine, benzene, even formaldehyde, are just a few of the synthetic chemicals commonly included in shampoos, skin creams and blushes - toxins which are absorbed into your skin with every use.'

Unlike food or drugs, cosmetics and their raw ingredients are not subject to review or independent pre-market approval, a situation criticised by experts including Dr Jean Munro, medical director of The Breakspear Hospital, Hertfordshire, which specialises in allergies and has seen 8,000 women since opening in 1982 - nearly all of whom were found to have a sensitivity to cosmetics.

'There is no question that people are being damaged by their cosmetics,' Munro said. 'How can they not be? So many things are put into cosmetics now that are carcinogenic and it is allowed because cosmetics are not considered to be as serious as drugs or food.'

Munro believes the presence of large numbers of even small amounts of banned substances means that, over time, users will have been exposed to danger.

"One of the most extreme cases I have seen was a woman whose bone marrow was affected by chemicals used in hair dye. The level of her blood platelets dropped and she broke out in a severe rash," she said. "The situation as it is is plainly dangerous - unacceptably so."