She is one of scores of young workers in the city of Suzhou who were poisoned by the chemical n-hexane, which they say was used to clean Apple components including iPhone touch screens.
Wu Mei – who, like the others, asked the Guardian to use her nickname – recalled her fear as her health suddenly deteriorated last spring.
At first, she thought she was simply tired from the long working hours at Wintek, a Taiwan-owned electronics giant supplying several well-known brands. She was weaker than before and noticed she could not walk so fast.
"Then it became more and more serious. I found it very hard to go upstairs and if I squatted down I didn't have the strength to get up. Later my hands became numb and I lost my balance – I would fall over if someone touched me," she said.
By summer, she was admitted to hospital, where doctors struggled to diagnose the cause. "I was terrified. I feared I might be paralysed and spend the rest of my life in a wheelchair," she said.
Because she was using n-hexane directly, she was one of the first and worst affected.
But more and more workers from the same room were suffering headaches, dizziness and weakness, and pains in their limbs.
An occupational diseases hospital which saw several victims diagnosed the problem in August and Wintek stopped using the chemical. But thanks to the previous months of exposure, at least 62 workers would require medical care. Many spent months in hospital.
Some believe more employees left Wintek after being taken ill, before they realised what was wrong.
Prolonged over-exposure to n-hexane can cause extensive damage to the peripheral nervous system and ultimately the spinal cord, leading to muscular weakness and atrophy and even paralysis, said Paul Whitehead, a toxicology consultant and member of the UK's Royal Society of Chemistry. It can also affect male fertility. Recovery can take a year or more.
The chemical's potential risks are well-known in industry, as are safe exposure limits. But the Wintek manager who decided to switch from alcohol to n-hexane for cleaning – apparently because it dried more quickly – did not assess the dangers. It was used without proper ventilation.
The change was obvious; workers disliked the pungent smell of n-hexane. But they had no idea it might affect their health. "We hadn't even heard of occupational illnesses before," said Wintek worker Xiao Ling.
"I'm very, very angry," added Wu. "I thought they behaved too badly."
Asked if they knew what products they were working on, three of the affected Wintek employees said team leaders told them they were working for Apple. They instantly recognised pictures of an iPhone and said they were cleaning touch screens, adding that items for other brands were not affected because Apple had isolated its production line. A lawyer acting for 44 of the poisoning victims also said several had named Apple.
Wintek, which does not discuss its clients, said it had replaced the factory's general manager.
It now notifies workers whose jobs may involve risk in advance, has tightened procedures for the introduction of new chemicals, and carries out medical checks. It has paid medical fees for those affected and says it will pay compensation according to the law.
Given that the assessment and appeals process for compensation can take as long as a decade, lawyers hope the firm will pay quickly as well as fairly.
Other patients at the hospital say they too became sick while using n-hexane on Apple products.