Oral cancer fear for Asians
As many as 600 million people around the world could protect themselves from cancer if they stopped chewing tobacco.
However, many are not aware of the risks associated with the habit, which is popular in south Asia and among ethnic groups in the West.
Chewing tobacco and betel quids, a mixture of tobacco, leaves and spices, is a significant risk factor for oral cancer.
In India, oral cancers account for four in 10 of all cancers. About 3,000 people are diagnosed with oral cancer in Britain each year. About half of these die.
Chetan Trevidy, an honorary clinical research fellow at Northwick Park Hospital in London, has set up a charity in the UK to try to increase awareness.
As well as heading Areca Concern, he also runs a clinic for people with cancer or pre-cancer of the mouth.
Mr Trevidy says one of the difficulties in getting people to stop chewing areca is that it has been a part of the Indian culture for centuries.
"Areca has been used for thousands of years and it is a very traditional part of the Hindu culture."
He suggests that banning the substance would be difficult.
"It is very difficult to separate the social cultural effects with the health damaging effects.
"A ban itself would be equivalent some people will say to banning smoking and alcohol."
Mr Trevidy suggests that only those people who chew areca on a regular basis should have cause for concern.
"If you chew it without the tobacco on an occasional basis there isn't much harm.
"My main worry is for those people who chew areca and tobacco on a regular basis, who may be addicted to it and who do not know they are addicted."
Those who do chew areca on a regular basis are advised to have regular medical and dental check-ups.
"Our advice is people should see their dentist and their doctor to make sure their mouth is checked every six months.
"The things I would be worried about are ulcers in the mouth that are non-healing, white or red patches and, in particular, having an inability to open their mouth wide or having intolerance to spicy foods," said Mr Trevidy.
Chewing areca is highly addictive and users often find it extremely difficult to give up.
"We did a study in north west London and we found it is as addictive as amphetamines," said Mr Trevidy.
"We have great difficulty weaning people off the habit because at the moment there are no substitute products. We are trying to find ways of helping these people but it is very difficult."
Bitan Patel, one of Mr Trevidy's patients, was told he would develop cancer if he didn't kick the habit.
"It wasn't easy to quit. I stopped because I had a problem in my mouth. I would have had cancer if I didn't stop it."