But increasingly, there is evidence of inadequate safety standards, poor quality control and slave labour.

Here, in an extract from his book about the toy industry, ERIC CLARK reveals the real cost of cheap toys from China.

Millions of Chinese factory workers toil through 80 hour-long weeks

Behind high fences, sprawling factory compounds stretch mile after dusty, depressing mile along the congested roads.

Guarded gates control entry and exit.

Adjoining many of the blocks are identical concrete boxes - the washing at the chicken wire-covered windows, adding flashes of colour, is the only indication that these are the dormitories for workers.

Here in the Pearl River Delta, China, the pollution levels are on average two or three times those permitted in the West.

But without places like this, with its swirling red dust, toxic rivers and thick, choking smog that hovers everywhere, stinging eyes and throats, the modern toy industry would not exist.

This is the hidden face of the trade where toys are produced for a few pence each by vast numbers of young Chinese people toiling in sweatshop conditions.

Between shifts the workers, mostly young women, their faces set in exhaustion, shuffle from building to building.

Shifts can last more than 15 hours a day, seven days a week - unlawful but far from uncommon.

The dominance of China in toy production is staggering.

There are about 8,000 factories employing some three million workers spread over six areas, of which the Pearl River Delta is by far the largest.

Virtually all the familiar Western toy names - led by U.S. giants Mattel and Hasbro - are made here. These workers make 80 per cent of all America's toys.

In children's picture books, Santa's beaming elves may still be making the toys, but the reality is that for elves we should read migrants - millions of them who have travelled by bus from rural areas up to three days' journey away, part of the biggest movement of people in human history.

Since the migration began, more than 50 million have passed through the factories of Guangdong province, where the Pearl River Delta lies.

If it is almost impossible to comprehend the scale of the movement of people, it is even more difficult for a Westerner to imagine the daily life of one of these toy workers.

Conditions obviously vary, from the acceptable to the unimaginably awful, but it is possible, from a host of reports and interviews conducted well away from factory premises, to construct a composite of the life and working conditions of one of the workers.

Li Mei is worn out, so she looks older than her 18 years.

Her skin is bad from too little daylight and she has many healing and still-open cuts on her hands.

Her neck, chest and forearms are heavily mottled with the raised red patches of allergy caused by toxic chemicals, which she scratches as she speaks.

She coughs a lot, and has chronic aches and pains, frequent headaches and blurred vision.

All these ailments have appeared during the past two years.

Li Mei is a migrant from the rural province of Western Sichuan.

At first, she is thrilled to be one of the dagongmei - the working girls - and to leave the hamlet where there are no roads and only limited electricity.

But she is frightened because the factories have a reputation as sweatshops.

Many return with disfigurements and illnesses.

And there was the fate of Li Chunmei.

Lin Chunmei, 19, was a 'runner' in the Bainan Toy Factory, rushing stuffed animals from one worker to the next for each step in production.

She collapsed one night, bleeding from nose and mouth, and was found hours later. She died before the ambulance arrived. Her parents were told it was an 'unknown death' and received a small sum in compensation.

But the villagers said it was the new disease, death from overwork.

Li Mei is certain nothing like this will happen to her: she is strong, accustomed to physically demanding tasks such as drawing water and cutting wood.

Her parents have borrowed heavily to buy the various personal documents she needs.

In four or five years, she plans to go home, buy a house and get married. She thinks about this all the time.

The factory where she toils is one of three buildings in a compound with high fences and a sliding metal gate, where two guards check everyone going in and out.

Beside it stands a warehouse and dormitory block. Li Mei's dormitory is on the eighth floor, a small room about 12 by 23 feet.

There are 32 rooms like it on this floor.

It is lit by a single fluorescent bar - her wages have the electricity costs docked - and the floor is concrete.

Double and triple bunk beds made of metal take up every inch of wall space.

During peak periods, when the factory takes on extra staff, girls often sleep two to a single bed.

Under the window, a grubby sink has a single tap. A notice is stuck to the wall, rules which another girl reads to her.

There are many, so she can remember only a few: 'No step on grass, offenders will be fined 50 yuan (£3.30).'

'No male or female staff going to the other gender's dormitory. The offender will be fired.'

Li Mei waits in a long queue of girls for the bathroom that two dozen people use to shower and wash their clothes.

She is still there at midnight, when everyone in the village has long been asleep, but the workers are only just off shift, too tired even to grumble as they wait in line.

Sometimes, the girl beside her says, 'there is no water even to brush your teeth, and the toilet is horrible.' The water (which, like lavatory paper, Li Mei is charged for) is cold.

By 2am she is finally in her lower bunk bed, separated from the hard surface by a straw mat even thinner than the one she uses at home.

Next morning she has no breakfast, for it is a meal she has to buy and prepare herself.

At 7.30am, in factory uniform of blue blouse with a white collar over trousers with her ID card displayed (she would be fined two days' wages if it was lost), she follows her guide through passages lined with cardboard boxes.

The air in the spraying and colouring department is filled with paint dust and smells sourly of chemicals -acetone, ethylene, trichloride, benzene.

The windows are fitted with wire mesh, the exits locked to prevent pilfering.

Noisy ventilators add to the din of the machines so the team leader has to shout to be heard.

Li Mei is given a blue apron and shown how to paint the eyes of the dolls with four pens of different sizes: she has to paint one every 7.2 seconds - 4,000 a day.

By the end of the second day, Li Mei's cotton mask and gloves are thick with paint particles and difficult to use.

She asks for new ones but is refused.

During the first few days, she finds the heat combined with the smell of chemicals repulsive.

She feels sick, has stomach-aches and is dizzy.

Once, when she faints, her section leader tells her to rest, rub on some herbal ointment then return to work.

Li Mei sneezes constantly and her eyes stream.

The bosses move her to the moulding department.

She feels a blast of heat - she is told later it rises to 104F - when the door is opened.

She is told to watch the other workers and then begins to stamp out parts of plastic dolls with repetitive movements performed many times a minute, 3,000 times a day.

Gloves are issued but no one can wear them - it is unbearably hot and they make it difficult to handle the tiny plastic parts: once the production line starts, her hands and eyes cannot stop for a minute.

Li Mei has to learn a lot of rules because she will be fined for any infringement.

Her section leader tells her there is to be no chatting, joking, laughing or quarrelling.

She must not disturb anyone's work, nap, or read a newspaper.

She must not fail to punch her work card, nor must she punch in for another worker.

She will lose two hours' wages for each minute she is late, and for half an hour she will lose a day's pay. For poor quality work, she may be dismissed or fined.

So she works carefully - and that means too slowly, so she is fined two days' pay.

Like most workers, Li Mei knows within a month that she is being unlawfully exploited.

She soon has wounds on her hands and elbows, and burn marks on her uniform.

When she is moved to a job trimming the plastic toys with small sharp knives, she often cuts herself, once so badly that her hand bleeds heavily - but the medical box is locked.

So she binds the wound up in cloth.

Worse things happen: workers in the die-casting and moulding departments lose fingers and even arms, while hole-making workers often have their hands punctured and crushed because they have no reinforced gloves.

With her tiny pay and all her debts, Li Mei cannot save.

She cannot resign from the factory but must apply for 'voluntary automatic leave'.

This means she would be severing the 'work contract' at her request.

As punishment she must forfeit one-and-a-half months' wages.

Without that, she does not have enough for the fare home.

Li Mei says: "I'm tired to death and I don't earn much.

"It makes everything meaningless." All she can do is go on.

"When we are working at the factory, we belong to the factory."

The American toy industry dominates the whole of the globe.

It is a $22 billion business. Every year it puts almost 3.6 billion toys into the home market alone, including 76 million dolls, 349 million plush toys, 125 million action figures, 279 million Hot Wheels and Matchbox cars.

Yet the toy business is no longer fun and games.

It's a harsh, corporate world, driven by social and demographic changes, concerns about stock prices and fierce battles between global brands.

By law, the maximum any Chinese worker should be on the assembly line is 53 hours per week.

But the China Labour Bulletin, a Hong Kong-based journal supporting independent unions and workers' rights, says 80 hours is common.

"Mattel has no way to know the truth about what really goes on here," said one worker. "Every time there is an inspection, the bosses tell us what lies to say."

This was supported by others who said that managers promised them extra pay if they pretended that they worked only eight hours a day, six days a week.

One government official, speaking on condition of anonymity, revealed that when government officers or foreign business executives visit the factories, the managers are tipped off beforehand and under-age workers are sent home.

In August 2006, the Chinese press carried the story of a female migrant worker who died from brain-stem bleeding after reportedly working non-stop for 21 hours in a toy factory in Zengzheng county in Guangzhou.

But it is unrealistic to expect that Chinese manufacturers will voluntarily improve conditions for workers.

The crux of the problem is this: by demanding that their suppliers produce goods at ever cheaper prices and demanding deadlines, the toy industry is almost forcing them to act illegally, despite the codes of practice it struggles to impose on them.

For consumers, this presents a dilemma which was neatly summed up for me by a couple pushing a loaded trolley down the toy aisles of a large superstore last Christmas.

"They're probably made under awful conditions but what do you do?" they asked.

"Accept it, or leave the kids with nothing."

The answer is not a boycott of Chinese toys.

Forcing factories to close and throwing millions of people out of work would harm the very people it was meant to help.

Instead, we must protest to the toy companies that we won't accept playthings for our kids which have been produced under horrific conditions and at the expense of workers.

After all, as this week's recall of Chinese-made toys shows, we too could end up paying a high price just for the benefit of buying cheap toys.