What’s the risk? Richard Boll/Getty

Do mobile phones increase the risk of cancer? An Italian court has ruled that heavy cellphone usage caused a man’s benign tumour, but there is still no convincing evidence that mobile phones increase the risk of cancer.

The man, Robert Romeo, says he spoke on a mobile phone for around 3 hours a day for 15 years while working for a telecoms company. In 2010, he was diagnosed as having a benign tumour in his right ear, and he lost the hearing in that ear when the tumour was removed.

It is understandable that if a person spends years with a cellphone pressed to their ear, they blame the phone if they get a tumour in that ear. But correlation is not causation.


Disappearing link

The news reports do not name the type of tumour Romeo had, but based on the fact that it was benign and resulted in hearing loss, it is likely to have been an acoustic neuroma, also called a vestibular schwannoma.

These tumours develop in the cells surrounding the ear nerve, and usually occur only on one side. What this means is that half of the people who get acoustic neuromas are going to get them in the ear they normally use for their phone.

So why did the Italian court decide that Romeo’s cellphone usage was to blame? The court has not yet released its reasoning, but a similar ruling in Italy in 2012 was based on a couple of studies that found a link between heavy use of analogue cellphones and a few types of cancer, including acoustic neuromas.

These were case-control studies, which involve asking people already diagnosed with cancer about their past phone use. But other case-control studies have failed to find a link, and this type of study is known to be a flawed way to identify risk factors for diseases.

Cohort studies are more reliable. These involve asking people about their lifestyle first and then following them up to see who develops cancer. In 2013, the largest cohort study done so far did report a link between phones and acoustic neuromas, but not any other cancers. However, when data covering a longer period was added, the link disappeared.

Preventing cancer

This is not surprising, given that there is no obvious reason why mobile phones would cause cancer. High-energy electromagnetic radiation such as X-rays can directly damage DNA, but the low-energy radiation from phones does not.

In theory, of course, there could be mechanisms we don’t yet know about. The World Health Organization’s International Agency for Research on Cancer is taking a cautious approach, listing mobiles phones as “possibly carcinogenic” in 2011.

But perhaps the biggest reason not to worry is that if using mobile phones greatly increased the risk of cancer, we should already be seeing a huge jump in the incidence of cancer, and that simply does not seem to be happening. Some studies have reported a small increase in certain cancer types, including acoustic neuromas, but this is usually attributed to increased diagnosis rates thanks to MRI scanning.

What’s more, brain tumours are thankfully rare. Fewer than 20 out of every million people will develop acoustic neuromas, for instance. Even if it was the case that heavy cellphone doubles the risk of tumours, the overall risk would still very low.

So if you’re worried about cancer, focus on the big, known causes such as smoking, alcohol and viruses like HPV. Making sure your kids are vaccinated against these viruses, for instance, will do far more protect them than trying to limit their phone time.

Read more: Relax – your phone probably isn’t going to give you cancer