London:
A large number of girls are now starting puberty at the age of nine, instead of 11 years, say scientists who claim the phenomenon could be linked to obesity or exposure to chemicals in the food chain.
A new study has revealed that breast development in a sample of 1,000 girls started at an average age of nine years and 10 months -- an entire year earlier than when a similar cohort was examined in 1991, 'The Sunday Times' reported.
The research was carried out in Denmark in 2006, the latest year for which figures were available, but experts say the trend applies to Britain and other parts of Europe. Data from America also point to the earlier onset of puberty.
The scientists have warned that such young girls are ill-equipped to cope with sexual development when they are still at primary school, and they could be at a greater long-term risk of developing breast cancer.
"We were very surprised that there had been such a change in a period of just 15 years. If girls mature early, they run into teenage problems at an early age and they're more prone to diseases later on.
"We should be worried about this regardless of what we think the underlying reasons might be. It's a clear sign that something is affecting our children, whether it's junk food, environmental chemicals or lack of physical activity," said Anders Juul of University hospital, Copenhagen.