Phthalates are man-made chemicals thought to interfere with the natural hormones that are crucial to overall health.

London - Chemicals found in PVC flooring, plastic shower curtains, processed food and other trappings of modern life may be sapping women’s interest in sex.

A study has linked low libido with the additives used to soften plastics which are found in every home.

Women with the highest levels of phthalates in their bodies were more than twice as likely to say ‘not tonight dear’ as those with the lowest amounts.

Phthalates are man-made chemicals thought to interfere with the natural hormones that are crucial to overall health.

They are found in everything from PVC flooring and shower curtains to car dashboards – and may also be in our food. Tiny particles can enter our systems either through breathing or eating.

Previous studies have linked them to diabetes and asthma. They have also been blamed for feminising the brains of baby boys and last year the World Health Organisation warned they have “serious implications for health”.

The latest research, presented at the American Society for Reproductive Medicine’s annual conference in Honolulu, suggests they are doing psychological, as well as physical, damage.

In the first study of its kind, Dr Emily Barrett, of the University of Rochester School of Medicine in the US, measured levels of phthalates in the urine of 360 pregnant women in their 20s and 30s.She also asked them how often they lost interest in sex in the months leading up to their pregnancy.

Those with the most phthalates in their bodies were two and a half times as likely to say they had frequently lacked interest in sex as those with the least.

She said: “It is interesting because these are chemicals that we are all exposed to every day. They are throughout our environment and every person studied showed measurable levels.”

Dr Barrett suspects that phthalates interfere with the production of sex hormones oestrogen and testosterone, both of which are involved in female libido.

She said that learning more is of “utmost importance”, adding: “For a lot of women with loss of libido there is no obvious reason and it is important to know how these chemicals might contribute.”

She said that food is a significant source of phthalates, particularly processed and highly-packaged products. It is thought to get into food from processing equipment and from packaging. Dr Barrett, who tried to avoid fast food when pregnant over fears that the chemicals it contains would harm her unborn baby, said: “One of the recommendations... to potentially lower your exposure is to eat less processed food and to pick fresh things without packaging.”

Other advice includes choosing natural wooden flooring over PVC and switching plastic shower curtains for glass screens.

Elizabeth Salter Green, director of campaign group CHEM Trust, said it is “highly likely” that phthalates are also found in British food. She said our exposure to them is ‘constant’ because they are used in so many products.

However relationship expert Dr Pam Spurr said many factors can influence a woman’s libido, including smoking, medication, having a baby or changing jobs.

A spokesman for the Chemical Industries Association, which represents manufacturers, said: ‘We are not aware of any globally accepted tests which can yet measure the effect chemical exposure may have on libido.’

He added that phthalates are among the most researched chemicals and the use of any that affect fertility is restricted.

Certain phthalates are banned from use in cosmetics, toiletries and toys in the EU and further restrictions are due next year. - Daily Mail