Parents could be putting their children at risk by using baby bottles made with ‘gender-bending’ chemicals, a charity has warned.

Bisphenol A mimics the female hormone oestrogen, and is understood to cause the early onset of puberty, low sperm counts, breast cancer and obesity.

It can pass from clear plastics into milk, water and juice – particularly when containers are heated.

The chemical is still used in nine out of ten plastic baby bottles – despite scientists raising concerns about it more than a decade ago.

The National Childbirth Trust called on manufacturers to put warning labels on bottles made with the chemical.

Scientists in the US have linked exposure to low levels with fertility problems, breast cancer and early puberty.

Canada is phasing out bottles made with Bisphenol A after its advisers said it could pose “a danger to human life or health,” while US store chain Wal-Mart – the world’s biggest retailer – is banning them.

Belinda Phipps, the chief executive of the National Childbirth Trust, said: “As a first step, it is important that bottles and other items that might reach a baby’s mouth are labelled in a standard and easy to understand way.”

Last month, American scientists working for a Government-funded research programme published results of their latest tests of Bisphenol A’s effect on animals.

They found that exposure to low levels “can cause changes in behaviour and the brain, prostate gland, mammary gland and the age at which females attain puberty”.

Babies are thought to be particularly vulnerable to the effects of the chemical because they are growing.

Earlier this year, another US study at the University of Cincinnati found that the level of Bisphenol A which leaches from plastic bottles increases dramatically when the containers are filled with hot liquids.

Elizabeth Salter Green, of the campaign group Chemtrust, called for Bisphenol A to be banned from all plastic products where there is a risk of leaching.

“It is unwise to make products for vulnerable sections of society using this chemical,” she said. “Because of its ability to leach out into milk, it should not be used in baby bottles.”

Asda, which is owned by Wal-Mart, said it had no plans to ban bottles containing Bisphenol A in the UK.

However, the supermarket is introducing a Bisphenol A-free range in the summer.

A spokesman for the Chemical Industries Association said the use of Bisphenol A in food and drink products was given the all-clear by UK and European food standards authorities last year.

“They have also confirmed that the trace levels to which we are exposed through eating and drinking do not present a health risk,” he said.

Via news.sky.com