Some girls now enter puberty as early as six - with toxic chemicals widely held to blame. But are new drugs to hold back the years really the right answer?:

Puberty is an unsettling stage in anyone's life, but if it happens at an age when you are still playing with dolls, it can be very worrying indeed.

That is exactly what happened to Lucia Reed. She was just seven when her periods started, an event which distanced Lucia from her classmates and led to unexplained medical examinations which terrified her.

'I felt completely alone and alienated, with this horrible secret,' she recalls 12 years later. 'I knew I was different from everyone else, but I didn't know what was happening.

'My mum had to tell the school, and they tried to make sure no one found out what was going on. Because of my periods, I was allowed to use a different loo from the other girls.

'Lessons like P.E. and swimming were a complete nightmare. I got teased because I had to wear a bra. So I used to pretend to have headaches and colds to get out of any sport.

'I also had to cope with terrible acne, greasy hair and huge mood swings. But I was much too embarrassed to discuss it with any of my friends. It wasn't until everyone else caught up with me at secondary school that I started to feel able to talk about it.

'My friends couldn't believe it when I finally told them - they said they felt really sorry for me.

'The scariest part was that because I looked older than I was, men would come on to me as though I was an adult, when actually I was 11.'

Doctors are increasingly worried about the number of girls - and boys - being referred to specialists because of this phenomenon of 'precocious' puberty.

The normal age at which puberty starts in both boys and girls has dropped by about two years since the 19th century, to 14 for boys and 12 for girls. This is largely due to improved nutrition - onset of puberty is believed to be triggered by physical size. Another theory is that the epidemic of obesity is to blame.

But modern social conditions may also be a contributory factor. Research suggests that children from broken homes experience earlier puberty. The stress of family breakdown apparently alters the balance of growth hormones and other chemicals in the body, speeding up a child's physical development.

Absent fathers may be another cause. American researchers have found that biological fathers send out chemical signals that inhibit their daughters' sexual maturity. Girls whose fathers had left home started their periods earlier.

Early puberty has even been linked to watching too much television. A few years ago, Italian scientists found that children who watched three hours a day produced less of the sleep hormone melatonin - low levels of the hormone play an important role in the timing of puberty.

But perhaps more worrying is the theory that it's exposure to environmental chemicals which is causing the drop in the age of puberty. These chemicals mimic the effect of hormones, disrupting the normal timing of sexual maturing.

Whatever the cause, growing numbers of children are being deprived of childhood and are turning, physically, into mini-adults at an increasingly young age. But without the emotional maturity to deal with these changes, they are vulnerable to exploitation.

In Britain, it is now estimated that up to at least one in six children under ten is affected. Indeed, there is a belief that schoolgirls as young as six are entering puberty.

In order to discover whether puberty really is arriving earlier, scientists are keeping track of 12,000 teenagers born in a 20-month period in what was the county of Avon (the group are now aged 14 to 15).

The Children Of The 90s study, as it is known, has already noted that breast development in the girls was happening at an earlier age than in previous generations.

Meanwhile, as highlighted in a forthcoming BBC radio programme, a debate is raging in the medical profession about what should be done about this trend: should powerful drugs, normally used to treat cancer, be routinely prescribed to young children to block the hormonal changes taking place in their bodies; or should the medically defined normal age range for onset of puberty simply be adjusted downwards so that the increasing number of children reaching sexual maturity while still at primary school are no longer viewed as abnormal?

Not surprisingly, the drugs industry supports the first approach.

In the past four years, drug manufacturers have alighted on this expanding market for premature puberty treatment. The hormoneblocking drugs Gonapeptyl and Decapeptyl have been licensed for use in children, although the manufacturers refuse to say how widely they are being prescribed.

A spokesman for Ferring, which makes Gonapeptyl, says the drug was licensed to treat girls who reached puberty before their ninth birthday and boys who reached puberty before the age of ten, but claimed it had not been on the market long enough to report what the take-up had been.

A different approach is being suggested by experts such as the American Academy of Pediatrics which wants to lower the age of 'normal' puberty to as young as seven.

Puberty involves huge physical, emotional and hormonal changes as the body prepares for reproduction. There is rapid growth and weight gain, the appearance of bodily hair and, for many, an unwelcome crop of acne. Girls develop breasts and begin having menstrual periods; boys begin to produce sperm and their voices become lower-pitched.

The generally accepted international standards of normal puberty for white girls were set by a study of 200 females in a British orphanage in the 1960s, which established that 12 years six months was the average age at which periods began. Similar studies of boys concluded that 14 was the average age of sexual maturity for them.

Over the centuries there has been a steady decline in the onset age for puberty. In Victorian times, it was about 15 for girls and older for boys; before that, records from Renaissance choirs show that youths of 17 and 18 were often still to hit puberty because their voices had not yet broken.

So far, there is no real agreement among doctors about whether we are just seeing a continuation of this decline in the average age at which puberty occurs, or whether it is part of a more worrying environmental trend towards children growing up too quickly.

However, most agree that if breast and pubic hair development happen before eight or nine in girls, or signs of puberty manifest themselves in boys under ten, it is 'abnormal'.

Gary Butler professor of paediatric endocrinology at Reading University, who is one of Britain's leading experts on the phenomenon of early puberty, is calling for urgent action to find out exactly how many children may be affected in order to address the growing fears of parents and teachers, who are having to deal with young children suffering the problems of teenagers.

'People are worried about this,' he says. 'There is evidence that children with precocious sexual development become sexually active earlier. It is our responsibility as the people best placed to know about it to come up with some answers.

'It is not just the social issue of having children able to reproduce at a very young age; we need to answer the question of whether early adulthood has a knock- on effect which makes them susceptible to adult health problems such as cancer and heart disease.'

He is embarking on his own study next January, which will aim to follow the development for the next five years of up to 1,000 seven-year-olds in Berkshire.

Their families will be asked to agree to regular weighing and blood tests to check for biochemical markers of puberty. They will also be asked to keep records of the children's diet.

Meanwhile, the data from the ongoing Avon study is being analysed by researchers at Emory University in Atlanta, Georgia - acknowledged world experts on environmental factors which affect human hormones.

These include a group of industrial chemicals called phthalates, which are linked to early puberty and have recently been banned from a vast range of cosmetics and household products.

Sally Watson, the spokesperson for the study, says: 'It is too early to say if early puberty is really affecting a lot of children or what might be causing it, but this study will give more information than any previous investigation because we have tracked these children since their mothers were pregnant.

'We know what age the mothers started their periods, we know about their weight and diet, and we will be able to see what is inherited and what isn't.'

Another question yet to be answered is whether the development of breasts and other signs of physical maturity mean that menstruation and full fertility are also starting sooner.

There are increasing reports of very young girls getting pregnant. Most recent statistics (for 2003) show 148 girls aged 13 or younger had abortions. However, it could be that although the whole process is inexplicably starting earlier, it is taking longer to complete, and that parents are worrying unnecessarily.

Professor Peter Hindmarsh, a specialist at Great Ormond Street Hospital for Children, says that while there might be a small shift towards earlier sexual maturity, early breast development is in parallel with the rising rates of obesity in young girls.

Ieuan Hughes, professor of paediatrics at Cambridge University, agrees that many young girls who seem to be developing breasts, are simply fat. 'There is a risk of overdiagnosing it,' he says. 'We have to do tests to establish hormone levels and bone development.

'Nevertheless, the earliest age for normal puberty is down to eight in girls and nine in boys. We are not jumping in to give treatment earlier in this clinic. We tend to ask the parents if they think their child is mature enough to cope with having periods, but it's a grey area.'

This debate is of little comfort to the thousands of families struggling to cope with this unexpected complication of child-rearing.

Now A 19 year- old art student, Lucia Reed lives with her mother, Miranda, in Ladbroke Grove, West London. Miranda, 55, who works as a specialist writer, and also has a 24-year- old daughter who did not experience early puberty, acknowledges that she found the experience almost as worrying as her daughter did.

'I first noticed she was getting hair under her arms when she was about six or seven, but I suppose I was in denial about it,' says Miranda. 'I didn't really talk to her about sex because she seemed too young, even though she looked a lot older.

'By the time she was ten, men were trying to pick her up. It was a very worrying time and there was not much advice available.'

Debbie Smith, 41, a GP dispenser, from Nottingham, tells a similar story. Her daughter. who is now 12, was just eight when she reached full sexual maturity.

'We felt very alone. We weren't even told drugs to stop puberty were an option,' says Debbie. 'Although I think she coped with it all reasonably well, she was very self- conscious in P.E. and swimming classes. She's now a mini-adult, but I don't let her dress older than her age and I do keep a close eye on her.'

But neither Miranda nor Debbie would have wanted their daughters to have taken hormone-blocking drugs. 'What we really need is for someone to recognise this is a horrible thing for the affected families,' says Debbie. 'We need more support.'