By Tony Cheng
BBC News, southern China
The huge army of migrant workers that has fuelled China's rapid expansion is beginning to think twice about the personal price they are paying for the Middle Kingdom's economic miracle.
These women are all showing symptoms of cadmium poisoning
For the first time in a decade, factory owners in the southern province of Guangdong are finding themselves with a labour shortage of up to two million workers.
New opportunities closer to home are deterring many from venturing south to the factories on the border with Hong Kong.
But for some, it is the health hazards that come with working in China's sweat shops that are keeping them away.
That has been the hidden cost for four women who were working in a battery factory in Huizhou, a mid-sized industrial town about three hours' drive from the provincial capital, Guangzhou.
They are all migrant workers from other provinces, but they have asked that their identities not be revealed.
"I had a throat problem back in 1999. I thought it was a cold and took some medicine which cost 1,000 yuan ($120). I got better, but then felt sick again a few days later. It kept repeating itself like this," one said.
The symptoms were shared by many of their colleagues. Now, the women have developed more extensive pains in the neck and waist, as well as other symptoms like memory loss.
Eventually, they decided to get tests taken. Blood and urine analysis showed that 90% of those tested had amounts of the chemical cadmium in their bodies that far exceeded recommended levels.
Cadmium is an essential component in the batteries they produced.
Tests have found it in the water supply; in the dust near the factory; and at seven times the safe limit in the homes of factory workers.
The workers are only issued with thin gloves
Ironically they had been producing rechargeable batteries - whose environmental credentials were stressed in the advertising campaign for the globally known brand.
The women were supplied with protective clothing by the factory, but it was not specialised. Their face masks were of the sort used to keep out traffic pollution in cities, and thin white cotton gloves.
When the company was confronted with the women's' illnesses, it showed little sympathy.
"It depends on how serious your symptoms are," said one woman. "The levels of compensation are between 5,000 and 8,000 yuan (US$600-950), but according to labour laws we have to leave the factory first. Only then can we get compensation".
The women intend to sue the company for compensation, healthcare and damages later this month.
But their lawyer Zhou Litai, a celebrated champion of Chinese workers' rights, says it is a problem that is all too common.
"The rights of workers are often violated like this," he said, speaking on the phone from his office in Chongqing.
"That includes work-related health problems, and a failure of workplace safety. They don't buy health insurance for the workers and there are lots of industrial accidents. All these problems happen very frequently," he said.
The courts do not show much sympathy either. Although China has very strict laws about the obligations of employers to protect their workers in dangerous environments, more than 100,000 people a year are estimated to die in work related accidents. Very few cases are brought against employers successfully.
But there are signs the workers may have found a way to fight back.
Joe Wang, a factory owner in nearby Zhongshan county, has noticed a trend this year.
Factory owner Joe Wang says there has been a drop-off in labour
"Since the spring festival, when we would normally expect a flood of new workers, there have been very few," he said, looking worried.
"These days they just won't come unless the wages are really good, the living conditions are better, and they don't have to do anything dangerous. If they can't find work like that they'll just stay at home," he said.
But for the women of Huizhou it is too late. Their health problems are unlikely to be easily fixed, and they can only hope the courts will offer them some compensation.
One of the women looked broken as she thought about the future.
"What about the next generation? What about the effects on their health? My health worries me a lot now. Whenever I think about it I get sad... my family gets sad too."