Ling Jianjun, 50, lost half of his jaw to oral cancer. From the front, his face looks like rotten wood.
A large, red scar stretches from the bottom of the right hand side of his chin down to his neck.
He is used to shocked glances from strangers when walking down the streets. He avoids using mirrors. Seeing his face reminds him of an experience so horrible he simply wants to forget it.
In September 2010, Ling, who lives in Xiangtan , a city in the southern province of Hunan , developed a canker sore inside his mouth and began a year-long quest for a treatment for it.
He first used antibiotics, on the advice of local doctors.
The sore went away for a while, but then grew back. Ling then started taking medicinal pills, but switched to liquid medicines after they stopped working. Finally, he could find nothing that worked.
His doctor could not understand the failure of the treatments, and sent him to a head and neck cancer expert at the Hunan Provincial Tumour Hospital.
"When Dr Li Zan took a glance in my mouth, he asked me two questions: 'Are you from Xiangtan?' and 'How long have you been chewing betel nuts?' '' Ling said.
"Yes, I am," Ling said, before answering: "For about 20 years."
"It is oral cancer. I'm certain about it," Dr Li said.
The doctor's answer shocked Ling, and he demanded a further examination. When the test results were released, they confirmed the diagnosis. Ling and his family panicked. The doctor suggested Ling have the cancerous tissue removed through surgery before it spread further. Ling accepted his advice and underwent a seven-hour operation.
His life was saved, but half of his jaw was gone.
"I'm lucky that I'm still standing. The rest of the patients in my ward are dead now," Ling said. "I hate betel nuts to death."
Local legend has it that, about 400 years ago, betel nuts helped stop an epidemic which spread through the city. As a result, betel nuts became a popular local snack. On the streets of Xiangtan today, the telltale rigorous jaw movement of betel chewers is a common sight - as is the spewing out afterwards of the reddish-purple juice produced.
Betel nut shops are everywhere - normally advertised using red signs. Within, the smell of camphor, mint and sweets is overpowering. Trays are piled high with dried black betel nuts for sale. And they are cheap.
The price of unpackaged nuts varies from 20 yuan (HK$25) to 60 yuan per half kilogram. A small snack pack usually costs 5 to 10 yuan.
They are marketed as being helpful in restoring energy and stimulating one's spirits. Long-haul drivers chew them in preference to drinking caffeine drinks in an effort to stop falling asleep.
They are also popular with mahjong players, who often play through the night in front of their small square tables.
While northern Chinese customarily greet people with cigarettes, people in Xiangtan offer betel nuts.
"I'm pretty sure they are addictive - worse than cigarettes. That's why I could not stop eating them for 20 years," Ling said. "After all, consuming betel nuts is deeply rooted in our culture, and it's a big industry."
Since the 1990s, Xiangtan has become the largest processing centre for betel nuts in China. It's estimated over 10,000 local workers are involved in the industry.
The Hunan Daily reported in mid-August that the top three betel nut processing enterprises - Pangge (meaning "fat brother"), Xiaolongqwang ("little dragon king") and Wuzizui ("five drunk men") - reported two to four billion yuan in annual revenue in the past three years.
Their products are also finding customers in parts of the mainland where people had never heard of betel nuts before, selling as far afield as Jilin and Heilongjiang in the northeast.
"The industry is indeed booming," the newspaper quoted a proud local official as saying.
But unlike cigarettes, there is little publicity about the health risks, let alone specific warnings that chewing betel nuts increases the risk of getting oral cancer.
By contrast, Taiwan, where betel nuts are a wildly popular traditional snack, has been educating people about the risks.
The Taiwan Cancer Society has published brochures explaining that betel nuts contain arecoline , which can lead to cancer. Besides common additives such as safrole, betel nuts also contain the toxic additive eugonol. According to the society, this can cause layers of cells in the mouth to waste away, leading to weight loss and inflammation.
According to research by Professor Ying-Chin Ko of Kaohsiung Medical University, betel nut addicts are 28 times more likely to get oral cancer than people who do not consume them. The risk for people who drink and smoke while chewing betel nuts is twice or three times higher than that, Ko's research indicates.
Taiwan reported 6,560 oral cancer patients among its population of 23 million in 2010, according to Professor L.J. Hahn of the school of dentistry at the National University of Taiwan. A year later, more than one third of those patients - 2,463 people - were dead.
Taiwan has designated December 3 its annual "Betel Nut Prevention Day" in order to educate the public about the dangers of chewing betel nuts.
Li Zan, of the department of head and neck surgery at the Hunan Provincial Tumour Hospital, has been treating betel nut addicts with cancer for nearly two decades. He usually operates on 50-60 oral cancer patients a month.
"Eighty per cent of my patients chew betel nuts. Many of them are from Xiangtan," he said. " The fact that local betel nuts are dried and processed with many additives increases the chances of oral sub-mucous fibrosis, precancerous lesions in the mouth."
There are no annual figures for new cases of oral cancer on the mainland. However, patients are dying in hospitals in Changsha and Xiangtan.
Before surgery Liu's weight was 75kg. Now he weighs 45kg. Surgery cost him part of his jaw, his gums and lymph glands and later caused blindness in his left eye. Tragically, the cancer has already spread to his brain.
"It's hard for me to tell him his true condition," said his wife Tang Na, 36. "I'm just counting the days left."
Liu can barely speak due to constant and severe pain. Most of the time he remains lying in his bed. His wife speaks for him.
Liu used to be work for the Xiangtan Iron and Steel Group. His colleagues all liked chewing betel nuts. But Liu surpassed many of them, chewing three packs of betel nuts a day.
"For a while I copied him and chewed betel nuts, too. We were both addicted," his wife said. "But I didn't chew as many as he did and I don't drink and smoke either. He did it all."
Liu could not control his craving for betel nuts for eight years until he was diagnosed with cancer. By then his teeth had become extremely sensitive and he could not eat any sour, spicy or sweet food, especially at very hot or cold temperatures. This is a common side effect afflicting betel nut addicts.
"What I feel puzzled about is why no one educates us that chewing betel nut is so deadly," Tang Na said. "I want to share our story with the public, otherwise my husband might die for nothing."
Ling Jianjun, the cancer survivor and a colleague of Liu, has now recovered.
A law graduate, he provides legal aid to people who have similar problems. In his spare time he works as a volunteer to explain the consequences of chewing betel nuts. "Look at me. Stop chewing betel nuts now," he tells people.
"Ultimately, the state should warn the public about the side effects of betel nuts and ensure related enterprises are transparent about the addictive qualities, or more people will die."
Betel nuts became a popular local snack in Xiangtan after they helped stop an epidemic which spread through the city about 400 years ago, according to local legend.
A TOXIC HABIT
- The nut is a seed of the areca palm, which grows in much of the tropical Pacific, Asia and parts of east Africa.
- Usually for chewing, a few slices of the nut are wrapped in a betel leaf, and cloves cardamom or other spices are added for extra flavouring
- The nuts reportedly help restore energy and stimulate one's spirits.
- Since the 1990s, Xiangtan has become the largest processing centre for betel nuts in China.
- More than 10,000 local workers are employed in the industry.
- WHO research indicates the chewing of betel nuts causes cancer
- The arecoline contained in the nuts can trigger the disease, the WHO says
- Many processed betel nut products also contain the toxic additive eugonol, which can cause the oral epithelial cell layer to atrophy, leading to consumers suffering weight loss and inflammation of the mouth