Scientists are calling for a ban on supermarket bacon and ham after the chemicals used in their production were linked to more than 50,000 bowel cancer cases.

A coalition of leading scientists says the refusal to ban nitrites - preservatives used to keep processed meats pink and long-lasting - has come at a devastating human and financial cost, with the NHS footing an estimated £3 billion bill to treat preventable cancers over the past decade.

Their analysis, based on figures from Cancer Research UK and the British Journal of Cancer, estimates that around 5,400 bowel cancer cases each year in the UK are caused by eating processed meats. Treatment costs for each patient average £59,000.

The warning comes exactly ten years after the World Health Organisation's International Agency for Research on Cancer (IARC) classified processed meat as a Group 1 carcinogen - placing it in the same risk category as tobacco and asbestos.

Despite this, ministers have done 'virtually nothing' to reduce Britons' exposure, according to Professor Chris Elliott OBE, founder of the Institute for Global Food Security and a former government adviser.

He said: 'A decade on from the WHO report, the UK Government has done virtually nothing to reduce exposure to nitrites - the curing agents that make these products pink and long-lasting but also create nitrosamines, compounds known to trigger cancer.

'Every year of delay means more preventable cancers, more families affected, and greater strain on the NHS.'

The scientists who worked on the original WHO report have now written to Health Secretary Wes Streeting urging him to ban nitrites in processed meats.

Their landmark report, published in 2015, analysed data from more than 800 studies and found that for every 50g of processed meat eaten a day, the risk of colorectal cancer increased by 18 per cent.

Experts say it is specifically the combination of nitrates and processing methods used in meats such as bacon, ham and sausages that generates carcinogenic compounds when consumed.

Currently, up to 90 per cent of bacon sold in the UK is thought to contain nitrites, which have been linked not only to bowel cancer but also breast and prostate cancers.

Professor Robert Turesky, of the University of Minnesota, who contributed to the original WHO report, said: 'When the IARC report was published in 2015, evidence linking processed meat to cancer was strong.

'A decade later, it is even stronger, and many preventable cancers have likely occurred. The evidence now calls for public health action.'

In their letter, the coalition urges the Health Secretary to mandate clear front-of-pack warnings on nitrite-cured products highlighting the cancer risk to consumers.

They also call for a long-term plan to phase out nitrite use in all processed meats sold in the UK, backed by regulatory measures to ensure compliance, and funding to help smaller producers switch to safer alternatives.

Although nitrite-free bacon and ham - often sold as 'naked' bacon - are available, they make up just five to ten per cent of the market, with almost all mass produced bacon sold in supermarkets containing nitrates.

The experts have also written to the European Union's health and food safety commissioner, urging similar action, while acknowledging that the EU has already begun to reduce permitted nitrite levels.

Professor Elliott, who also led the Government's investigation into the horsemeat scandal, said manufacturers should adopt natural curing alternatives already proven safe and effective.

He added: 'Every year of delay means more preventable cancer, more families affected and greater strain on the NHS.'

Current NHS guidelines advise limiting processed meat consumption to no more than 70g a day - around two rashers of bacon.

However, the World Cancer Research Fund and American Institute for Cancer Research recommend eating very little, if any.

Bowel cancer is the fourth most common cancer in the UK, with around 44,000 new cases a year, and 142,000 in the US.

Symptoms include changes in bowel habits such as persistent diarrhoea or constipation, a feeling of incomplete emptying, and blood in the stool. 

Stomach pain, bloating, unexpected weight loss and fatigue are other warning signs.

The late Dame Deborah James, nicknamed Bowelbabe, raised more than £11.3 million for Cancer Research UK and was widely credited with increasing awareness of the disease before her death in 2022, aged 40. 

It comes as a major new global analysis across 42 countries found that colon cancer - the form which claimed Dame Deborah's life - is the only cancer rising exclusively among under-50s.

In England, diagnoses among 25 to 49-year-olds have increased by more than 50 per cent since the early 1990s.

Cancer Research UK estimates that more than half (54 per cent) of bowel cancer cases in Britain are preventable.