What does "Group 2B possibly carcinogenic" actually mean?

In 2011, the International Agency for Research on Cancer (IARC), part of the WHO, placed radiofrequency electromagnetic fields — the kind phones emit — in Group 2B: "possibly carcinogenic to humans." This is a precautionary label that means the evidence is limited and a risk cannot be completely excluded. Group 2B also includes things like aloe vera extract and pickled vegetables. It is not the same as Group 1 ("carcinogenic"), which contains tobacco and asbestos. The classification reflects scientific caution, not proof that phones cause brain tumours.

Is the radiation from mobile phones the same as from X-rays?

No — and this is the most important distinction. Mobile phones emit non-ionising radiofrequency radiation, which does not have enough energy to break the chemical bonds in DNA. X-rays and CT scans emit ionising radiation, which can damage DNA and is an established cause of some tumours. The only confirmed effect of phone-level radiofrequency energy is very slight, harmless tissue warming. The "radiation" in a phone is far closer to the energy of a radio or microwave signal than to a medical X-ray.

Do children face a higher risk from mobile phones?

This is an open question scientists take seriously, because children's skulls are thinner and their nervous systems are still developing. The CEFALO study, which looked at brain tumours in children and teens aged 7–19, found no clear link with mobile phone use. Still, because children today will use phones for far longer over a lifetime than any studied generation, many health bodies recommend precautionary habits — texting over calling, using a headset, and limiting screen time — while research continues. There is currently no evidence of harm, but no long-term lifetime data yet either.

How can I lower my exposure to phone radiation, just in case?

If you would feel better reducing exposure, these steps are simple and carry no downside: use a wired headset or the speakerphone so the phone is away from your head; text instead of calling when you can; avoid long calls in areas with weak signal (phones boost power to connect); keep the phone off your body — out of a chest or trouser pocket — when not in use; and avoid sleeping with the phone next to your head. None of these are proven to reduce any real risk, but they cost nothing and offer peace of mind.

What actually does raise the risk of a brain tumour?

For most people, the cause of a brain tumour is never identified. The few established risk factors are: previous high-dose ionising radiation to the head (for example, radiotherapy for an earlier cancer); rare inherited genetic syndromes such as neurofibromatosis, Li-Fraumeni syndrome, and tuberous sclerosis; and increasing age for certain tumour types. Lifestyle factors that drive many other cancers — smoking, alcohol, diet — have not been shown to cause primary brain tumours. Mobile phone use is not on the established-risk list. Read more on whether brain tumours can be prevented.

I have headaches and use my phone a lot — should I be worried?

Frequent headaches are very common and are almost never caused by a brain tumour or by phone use. Eye strain, poor sleep, stress, dehydration, posture, and ordinary tension or migraine headaches explain the vast majority. The headaches that warrant a doctor's review are those that are new and persistent and getting worse over weeks, are worst in the early morning or wake you from sleep, or come with vomiting, a first-ever seizure, one-sided weakness, or sudden vision changes. If that describes you, see a doctor for a proper assessment — but the cause is far more likely to be benign than a tumour, and it is not your phone.