The pointless, self-defeating burning of ash trees could have been avoided

If it hadn't been for a name-related confusion, the government might have imposed a ban on imports of ash and ash products years ago.

What’s in a name? Ash fungus by any other name would have burned as sweet in the recent bonfires. But the name does make a difference. Had it not been for name-related confusion, the government might have imposed a ban on imports of ash and ash products years ago. Then the pointless, self-defeating burning could have been avoided.

EU rules prohibit a ban on imports of a species if the threatening pathogen is already endemic. The ash fungus is widely reported as being Chalara fraxinea. This is widespread in the UK, and benign: no ban was possible. However, many fungi exist in two forms, one that reproduces sexually, and one that reproduces asexually. In 2009, researchers suggested that the pathogen was in fact Hymenoscyphus albidus, a sexually reproducing version of Chalara fraxinea. A ban, then, was still impossible. But last year Swiss researchers showed the pathogen to be a different organism that they named Hymenoscyphus pseudo-albidus. That could have been banned.

Things could get worse. A decision taken at the International Botanical Congress in Melbourne last year means that mycologists – those who study fungi – will no longer be allowed to give separate names to the sexually and asexually reproducing variants of a species. Ironically, the idea is to limit confusion. With all the evolving variations of our forest pathogens, it’s likely to cause more problems than it solves.

Evolution is fearsome to behold. We’ve been watching it in our hospitals for years – it is what gave us our antibiotic-resistant superbugs. Put a wide variety of bacteria together in a confined space with plenty of very habitable niches and they will indulge in an orgy of gene-swapping. This creates new strains, many of which are resistant to all known toxins.

Ash dieback is another example of an evolved pathogen. It arose in Poland in 1992. There is nothing we can do about it except let the naturally resistant trees emerge as winners in the evolutionary arms race. It’s impossible to tell which trees will survive without carrying out a genetic analysis; that’s why burning swaths of ash trees is self-defeating.

In truth, the issue over naming the fungus is probably a convenient scapegoat. Researchers were advising an import ban years before anyone looked into whether the fungus was of an endemic species. Somehow, no one wanted to react to the threat, and it’s not just the UK’s researchers who didn’t want to see the coming evil: Danish experts pointed out an impending problem to the Swedes, and they did nothing either.

Import duty

What we can do now to safeguard the future of our forests is reduce the demand for imported plants. Read the scientific literature on plant pathogens, and you find that experts are issuing 13 times as many alerts on new plant-infecting fungi as they were in 1995. The ash fungus may be one of the relatively few natural mutations that have occurred in recent times: most of them are triggered by human activities. Plant pathologists put the blame squarely on the taste for imported plants.

Our craving for exotic plants and ready-grown trees for our gardens and public spaces has moved plants and their pathogens around the world in unprecedented numbers. In new environments, the pathogens swap genes and evolve into forms for which native species have no resistance.

The surging global trade in plants is essentially a huge microbiology experiment that is destroying the world’s forests. But perhaps we think that interesting suburban gardens are worth it?

Michael Brooks’s “The Secret Anarchy of Science” is published by Profile Books (£8.99)

 

Ash trees in Pound Farm Woodland, where many have been identified as having Ash Dieback Disease. Photograph: Getty Images

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

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Scientists have finally said it: alcohol causes cancer

Enough of "linked" and "attributable": a new paper concludes that alcohol directly causes seven types of cancer.

I don't blame you if you switch off completely at the words "causes cancer". If you pay attention to certain publications, everything from sunbeds, to fish, to not getting enough sun, can all cause cancer. But this time, it's worth listening.

The journal Addiction has published a paper that makes a simple, yet startling, claim: 

"Evidence can support the judgement that alcohol causes cancer of the oropharynx [part of the throat], larynx, oesophagus, liver, colon, rectum and [female] breast"

So what's especially significant about this? 

First, scientists, unlike journalists, are very wary of the word "causes". It's hard to ever prove that one action directly led to another, rather than that both happened to occur within the same scenario. And yet Jennie Connor, author of the paper and professor in the Preventive and Social Medicine department at the University of Otago, New Zealand, has taken the leap.

Second, alcohol not only causes cancer of one kind – the evidence supports the claim that it causes cancer at seven different sites in our bodies. There was weaker evidence that it may also cause skin, prostate and pancreatic cancer, while the link between mouth cancers and alcohol consumption was the strongest. 

What did we know about alcohol and cancer before?

Many, many studies have "linked" cancer to alcohol, or argued that some cases may be "attributable" to alcohol consumption. 

This paper loooks back over a decade's worth of research into alcohol and cancer, and Connor concludes that all this evidence, taken together, proves that alcohol "increases the incidence of [cancer] in the population".

However, as Connor notes in her paper, "alcohol’s causal role is perceived to be more complex than tobacco's", partly because we still don't know exactly how alcohol causes cancer at these sites. Yet she argues that the evidence alone is enough to prove the cause, even if we don't know exactly how the "biologial mechanisms" work. 

Does this mean that drinking = cancer, then?

No. A causal link doesn't mean one thing always leads to the other. Also, cancer in these seven sites was shown to have what's called a "dose-response" relationship, which means the more you drink, the more you increase your chances of cancer.

On the bright side, scientists have also found that if you stop drinking altogether, you can reduce your chances back down again.

Are moderate drinkers off the hook?

Nope. Rather devastatingly, Connor notes that moderate drinkers bear a "considerable" portion of the cancer risk, and that targeting only heavy drinkers with alcohol risk reduction campaigns would have "limited" impact. 

What does this mean for public health? 

This is the tricky bit. In the paper, Connor points out that, given what we know about lung cancer and tobacco, the general advice is simply not to smoke. Now, a strong link proven over years of research may suggest the same about drinking, an activity society views as a bit risky but generally harmless.

Yet in 2012, it's estimated that alcohol-attributable cancers killed half a million people, which made up 5.8 per cent of cancer deaths worldwide. As we better understand the links between the two, it's possible that this proportion may turn out to be a lot higher. 

As she was doing the research, Connor commented:

"We've grown up with thinking cancer is very mysterious, we don't know what causes it and it's frightening, so to think that something as ordinary as drinking is associated with cancer I think is quite difficult."

What do we do now?

Drink less. The one semi-silver lining in the study is that the quantity of alcohol you consume has a real bearing on your risk of developing these cancers. 

On a wider scale, it looks like we need to recalibrate society's perspective on drinking. Drug campaigners have long pointed out that alcohol, while legal, is one of the most toxic and harmful drugs available  an argument that this study will bolster.

In January, England's chief medical officer Sally Davies introduced some of the strictest guidelines on alcohol consumption in the world, and later shocked a parliamentary hearing by saying that drinking could cause breast cancer.

"I would like people to take their choice knowing the issues," she told the hearing, "And do as I do when I reach for my glass of wine and think... do I want to raise my risk of breast cancer?"

Now, it's beginning to look like she was ahead of the curve. 

Barbara Speed is a technology and digital culture writer at the New Statesman and a staff writer at CityMetric.