Has it been proved that mobile phones (cellphones) cause cancer?

There has been a certain amount of panic in the news about data from a US National Toxicology Program study where rats were exposed to cellphone radiation and it has been claimed there was evidence of cancer being caused.

The quick answer is no, it hasn't been proved. There is no good evidence to say that mobile phones aren't safe. Keep using them!

There are far more studies suggesting no link at all - so immediately we have to take any findings with a pinch of salt. As is made clear in Science for Life, a single study is never enough to provide useful guidance as any study can be flawed, and it's important to take in the bigger picture. But also the actual findings of this study aren't as negative as the headlines suggest.

First, the study involved exposing rats (with much less brain shielding than humans) to 9 hours of phone radiation a day for the whole of their lives. That's a lot. No females developed any problems, but 3 per cent of the males developed brain cancer. However, experts have pointed out that the number of cancers was small enough to be a statistical occurrence. What's more, most rats were exposed to higher intensity radio waves than are allowed from a mobile phone - and stranger still, the rats that were exposed to the radio transmissions lived longer than a control group that wasn't exposed.

All this strongly indicates that there is nothing negative to be learned from this trial. See the NIH for details.

Are microwave ovens dangerous?

At any one time there are a number of posts circulating on social media, or by chain emails, suggesting that microwave ovens present a danger to health. But is it true?

Generally speaking, the assaults on microwaves either suggest that the damage and de-nutrify food, or that the microwaves themselves are zapping us as we stand around the kitchen.

Let's take the food part first. It is certainly true that microwaving reduces nutritional value - but so does all cooking. On the whole, cooking in a microwave is more likely to retrain nutrients than using conventional means of cooking. Some of this is probably due to the reduced cooking time. Of course it's perfectly possible to cook vegetables for longer than usual in a microwave in a container with lots of water - and just like boiling vegetables excessively in conventional cooking, this is a great way to remove nutritional value. Like any other means of cooking, it's possible to microwave badly.

Another food claim is that microwaving produces carcinogens - again, this is a typical outcome of cooking, though unless you char your food, the amount of carcinogens produced is likely to be lower than the levels of natural carcinogens that are in food anyway. It is sensibly recommended that some plastics aren't used in microwaves, but this is because they melt, not because they give off nasty toxins.

How about the stray microwaves? Studies of undamaged microwaves have shown practically no leakage - well below safe levels. It is important to replace a microwave if door hinges etc. get damaged, but if your microwave is in good condition, the amount of microwaves that can leak from it is tiny and harmless. Those who don't like microwaves will always refer to them as 'radiation' because this sounds scary. They are indeed radiation, but only in the same sense that light, for instance, is radiation. We are not talking about nuclear radiation, but electromagnetic radiation - things like radio waves and light. 

Nothing that makes things hot is totally harmless. You can get burned from hot food in microwaves. Microwaves are susceptible to uneven cooking - so it's important that you make sure the turntable is working properly and that you stir food as required. And it is possible for some liquid microwaved foods and drinks to spurt when, say, a spoon is put in them - so care is important. You shouldn't leave a microwave in the charge of a five-year-old, any more than you should a conventional oven. But all the negative comments about microwaves beyond this simple safety requirement seem to come from a very small number of sources, some of which have a vested interest in selling 'radiation meters' etc., while those regarding microwaves as safe are proper scientists, engaging in well-reviewed scientific trials. 

LINKS

• Burned food - page 15

Phone chargers and the environment

A plugged-in phone charger with no phone attached does use electricity - but not very much.

We are often warned of the dangers to the environment of leaving phone chargers plugged into the mains because they are still using current. This can seem a little counter-intuitive. After all, an electrical socket doesn't leak electricity when there's no plug in it, so why should a phone charger, if there is no phone attached?

Unlike the socket, the charger has something at work even if there is no phone present. The charger has to convert the high voltage AC current of your mains down to the low voltage DC used to charge a phone. This involves passing the mains current through a transformer, and transformers have two complete electrical circuits, one for the input and one for the output. This means that the input circuit does use power, even if there is no device to receive the output. (Contrast this with the electrical socket, where the circuit is broken unless something is plugged in.)

However, the power usage of such a charger when not in use is tiny - around 0.1 watts. Compare that with a traditional bright light bulb at 100 watts - it's 1/1000th the amount. So by all means unplug your phone charger when not in use, but don't think it's going to make a big difference. You can do far, far more by switching to LED light bulbs, fitting double glazing, turning the heating down by 1 degree, insulating your house better and all the other ways that are traditionally recommended for saving energy.