Friday, 27 July 2018


Scarcely a week goes by without a headline-grabbing story about risks to our health that are associated with the enjoyment of food and drink we all thought was perfectly safe. And tabloid editor’s love these stories because anything that feeds public alarm sells papers. Usually the stories are based on epidemiology, which studies the incidence of disease in populations and the risk factors that correlate with them.

An example is a World Health Organisation report that classified processed meat such as bacon and sausages as carcinogens because the cooking process causes the production of acrylamide, which in large doses has been shown to cause cancer in mice. The tabloid headlines included “A bacon sandwich a day causes cancer”; “A bacon sandwich a day ‘increases the risk of colorectal cancer by 16%’ - experts say.”

A survey showed that nearly 50% of people in all age groups were aware of this conclusion and around a third of people said they were trying to cut down on consumption. And this was reflected in sales figures. In the four weeks after the publication of the WHO’s report and the headlines accompanying it, sales of packs of bacon in the UK fell by 8.5%, and this appears to have been a stepped change that hasn’t reversed itself. So, were the headlines justified, and what sense should we make of this and similar stories?

One of the most erudite commentators on how supposed risks are communicated to the public is Sir David Spiegelhalter, Professor for the Public Understanding of Risk at the University of Cambridge. He’s written extensively on how to spot the difference between a health risk and a health scare. He suggests that to understand the true scale of a risk, put it into the context of how the supposed risky behaviour would impact on a hundred people.

The bacon sandwich scare is a case in point. Spiegelhalter says that if a hundred people never eat a bacon sandwich, or otherwise consume bacon, ever, then nevertheless, six of them will develop colorectal cancer at some point in their lives. In the alternative, if a hundred people eat a bacon sandwich every day of their adult lives then seven of them will develop colorectal cancer. So, consider the logistics here: a hundred people, each eating a bacon sandwich a day, 365 days a year for, say 50 years, equates to the consumption of 1,825,000 bacon sandwiches! And this is the level of consumption needed to for one extra person in this group of a hundred to develop colorectal cancer. This is a health scare, not a real-world health risk.

For the alcophobes’ of public health, the lesson of this scare and the impact it had on sales of bacon, has not been lost. They recognise that attaching the words ‘cancer risk’ to the consumption of alcohol is a powerful means of scaring people into believing that big risks are involved even in relation to moderate consumption. In relation to breast cancer, which is what drives public health claims that “there is no safe level of drinking”, the lifetime risk of a female ‘never drinker’ developing breast cancer is just under 10%. For women who regularly drink moderate amounts of alcohol it elevates to just over 11%.

In round figures, if a hundred women never drink alcohol in the entire lives, nevertheless 10 of them will develop breast cancer at some point. In the alternative, if a hundred women drink two glasses of wine a day, then 11 of them will develop breast cancer at some point.  So, consider the logistics: if a hundred women each drink two 125ml glasses of wine a day, totalling three units of alcohol, every day for 50 years then that is 5,475,000 units of alcohol – which equates 608,333 75cl bottles of wine with an ABV of 12%! And this is the level of consumption needed for one extra person in this group to develop breast cancer. This is a health scare, not a real-world health risk.

The other thing that temperance lobby alcophobes’ understand is that in the public imagination cancer is always fatal. But 90% of breast cancer is not fatal and meta-analysis shows no link between moderate consumption of alcohol and breast cancer mortality, nor its recurrence (Gou et al 2013). A large study which followed up women with breast cancer correlated with better chances of survival if they were regular drinkers before diagnosis.  If they altered their drinking after diagnosis this had no link to their chance of dying from breast cancer, but an increase in drinking was associated with an overall increase in life expectancy, largely due to substantially fewer heart disease deaths among those who increased their alcohol consumption (Newcomb et al 2013).

So, much more needs to be done to promote public understanding of risk, otherwise the food and drink industry will continue to be subject to misleading scare stories from lazy journalists who fail to challenge the sensationalist claims of nanny-state health scolds.

Friday, 6 July 2018

Will cannabis kite go up in smoke?

The issue of legalising cannabis has been in the news in recent weeks. It began with the heart-rending story of a small boy having up to 50 epileptic seizures a day and his mother’s wish for him to receive medicinal cannabis oil which relieved his symptoms. The Home Secretary obliged with a temporary licence but made it clear there were no intentions to legalise cannabis for recreational use.

The only mainstream political party in the UK that supports the creation of a legal, licensed market for recreational cannabis is the Liberal Democrats. However, pressure for change is increasing, with Canada and nine US states legalising cannabis for “medicinal purposes” or full legalisation. Can change in the UK be far behind?

What are the arguments? Research indicates about three million UK adults regularly smoke cannabis – 7% of the adult population. The reputation of cannabis as a “soft drug” has become tarnished in recent years because the nature of cannabis itself has changed. Let me explain. Cannabis contains two chemical compounds – tetrahydrocannabinol (THC) and cannabidiol (CBD) – and it’s the THC that gets you stoned! But THC can also cause mental health problems in a small but significant number of users – particularly people with a history of mental illness. High doses of THC can cause psychotic episodes and paranoia. CBD, on the other hand, acts as a natural anti-psychotic medication and mitigates the chances of the mental health problems that can arise from THC use.

“Traditional cannabis” contained a balanced mix of THC and CBD but in the first decade of this century it was pushed out of the black market by sinsemilla – “skunk” – which has a high level of THC and very little CBD. Mental health referrals began to climb. Between 2006 and 2014 it is estimated the use of skunk declined 25% but THC-induced mental health referrals rose 50%. Skunk is a product of cannabis prohibition because it can be grown indoors using hydroponic equipment and doesn’t need to be smuggled-in across borders.

Those advocating legalisation argue we’ve failed to suppress the mass market for cannabis and a licensed, legal market would be a better way of managing use and reducing harm. However, this is not a simple or one-sided argument. If legalisation is to deliver better outcomes and eliminate the black market for skunk, the government would have to get the licensing model right.

How might this work? First, government would have to mandate a maximum level of THC (say 15%) and a minimum level of CBD to create a safer product. But the new, legal, “safer” cannabis would also have to be cheaper than black market skunk. There’s plenty of margin to play with as a gram of skunk currently sells for about £10 so there is a margin for producers, retailers and government, which would introduce a cannabis duty and levy VAT. It would also be necessary to ensure the product was easily available at chemists, off-licences and a network of cannabis cafes.

But let’s take a step back. If we enable a new, fully legal industry of intoxication and make cannabis safer to use, cheaper to buy and even easier to get hold of, what would happen to the level of demand? Again, research indicates a 10% reduction in price would trigger a 7% increase in consumption – at a time when it is falling. But it would be increased consumption of a safer product. Police time would be saved and government would gain perhaps £1bn a year in tax revenues.

Here’s where it gets complicated. THC-induced mental health problems didn’t start with skunk – they just got worse. So if consumption of legal cannabis remained the same, the incidence of mental health referrals would fall. If consumption significantly increased, the incidence of mental health referrals would still fall but the absolute number might rise.

You can see why this is a difficult issue for politicians. On the face of it, if we accept we can’t suppress a mass market in an open society and a failed policy of prohibition just lines the pockets of criminals, licensing sales of a quality-controlled product where we can control strength and ingredients and deliver a revenue stream for government seems a win-win situation. But think how the Daily Mail would spin this. Who would grow and produce cannabis products? The tobacco industry is best placed to do so. And who would retail them – bar or coffee chains? You can imagine the narrative of those opposed to change – Big Tobacco and Big Alcohol are behind this.

My own view is that, on balance, a licensing system offers a better chance of public protection and harm reduction than the status quo. But politically, I just don’t think this kite will fly in the UK.