Up to 80 tonnes of plastic could enter the sea every year from everyday cosmetics and cleaning products, according to a new study.

Research has shown almost 100,000 tiny "microbeads" - each a fraction of a millimetre in diameter - could be released in every single application of a cosmetic.

Scientists at Plymouth University said that due to their small size it was expected many would not be intercepted by conventional sewage treatment and were so released into rivers and oceans.

They estimate this could result in up to 80 tonnes of microplastic waste entering the sea every year from use of these cosmetics in the UK alone.

By way of comparison, the annual country-wide weekend beach clean-ups organised by the Marine Conservation Society typically collect around nine tonnes of litter per year.

Microplastics have been used as bulking agents and abrasives to replace natural exfoliating materials in cosmetics.

They are found in a variety of products such as hand cleansers, soaps, toothpaste, shaving foam, bubble bath, sunscreen and shampoo.

The latest study was led by PhD student Imogen Napper, together with Professors Richard Thompson and Steve Rowland, and Dr Adil Bakir.

Miss Napper said: "As the study unfolded I was really shocked to see the quantity of microplastics apparent in these everyday cosmetics.

"Currently, there are reported to be 80 facial scrubs in the UK market which contain plastic material.

"However some companies have indicated they will voluntarily phase them out from their products.

"In the meantime, there is very little the consumer can do to prevent this source of pollution."

For this study, the researchers chose brands of facial scrubs which listed plastics among their ingredients and subjected them to vacuum filtration to obtain the plastic particles.

Subsequent analysis using electron microscopy showed that every 150ml of cosmetic product could contain between 137,000 and 2.8 million microparticles.

Professor Richard Thompson, who has been studying the effects of litter in the marine environment for over 20 years, said: "Using these products leads to unnecessary contamination of the oceans with millions of microplastic particles.

"There is considerable concern about the accumulation of microplastics in the environment.

"Our previous work has shown microplastics can be ingested by fish and shellfish and there is evidence from laboratory studies of adverse effects on marine organisms."

The research paper, Characterisation, Quantity and Sorptive Properties of Microplastics Extracted From Cosmetics, has been published in the journal Marine Pollution Bulletin.