Daily Mail | April 7, 2010
By David Derbyshire

Gender-bending chemicals used in food cans, shower curtains and toys may be triggering early puberty in girls - and putting them at greater risk of cancer and diabetes, researchers say.

A study has found evidence that three classes of hormone-mimicking chemicals disrupt the bodies of girls approaching adolescence.

Although the association is 'weak', the scientists say it raises serious questions about the causes of early puberty.

The average age of puberty in girls - ten years and three months - has fallen by more than a year in a single generation.

Doctors say improved diet and higher body weights of children is mostly to blame. 
But some researchers believe environmental chemicals that mimic the sex hormone oestrogen could also be a factor.

The latest study found that exposure to three chemical classes - phthalates, phenols and phytoestrogens - can 'disrupt the timing of pubertal development' in young girls. 
Phthalates are banned in cosmetics in Europe, but are allowed in the U.S.

Phenols include the widely used chemical Bisphenol A - which is used in the lining of food cans and shatter-proof baby bottles. Phytoestrogens are naturally occurring chemicals found in soya, bread, cereals and nuts.

In tests, girls with the highest concentrations of some of the substances in their bodies tended to develop breasts and pubic hair earlier than those with the lowest levels.

Other chemicals appeared to delay puberty.

'Research has shown that early pubertal development in girls can have adverse social and medical effects, including cancer and diabetes later in life,' said Dr Mary Wolff, of Mount Sinai School of Medicine in New York.

'Our research shows a connection between chemicals that girls are exposed to on a daily basis and either delayed or early development. While more research is needed, these data are an important first step in evaluating the impact of these common environmental agents in putting girls at risk.'

The findings come from a study of 1,151 American girls. The girls were aged between six and eight at the start of the study and were monitored for up to two years.

The scientists-found that all three chemicals were widely detectable in the girls' urine samples.

High exposure to some of the hormone-mimicking chemicals was 'weakly associated' with early signs of puberty. Exposure to others appeared to delay puberty. 
The strongest links were seen with phthalates and phytoestrogens.

'We believe that there are certain periods of vulnerability in the development of the mammary gland, and exposure to these chemicals may influence breast cancer risk in adulthood,' Dr Wolff said.

Around a third of the girls in the study were showing signs of early puberty.

Hormone-disrupting chemicals can interfere with the body by mimicking oestrogen - or by blocking it. Their impact depends on the dose and their location in the body.

British puberty expert Professor Fran Ebling, of Nottingham University, said: 'Most of the associations in this study were weak and we know that weight is a much better predictor of early puberty. But this is a very well-designed study.

'There really is evidence that the average age girls are starting to develop breasts and pubic hair is getting lower so there's a lot of controversy as to why this is.

'Most of the evidence points at body, but there's a faint suspicion that environmental chemicals could be playing a role too.'