Are powerlines, phones, radio masts and communication devices causing cancer?
This is one of the most common queries (more often framed as a statement) that we receive in the Irish Cancer Society. We therefore thought we’d spend a little time giving some facts to this frequently asked question.
We’re going to look to research to answer this query over two articles. Part 1 focuses on powerlines, and Part 2 next month will focus on communications masts, mobile phones, Wi-Fi, etc.
The quick answer is powerlines and masts do not cause cancer. But read on for a little bit more detail which hopefully explains things a bit better.
Electricity and magnetism are all around us and always have been. Any flow of electricity generates a changing magnetic field (called an electromagnetic field, EMF) radiating invisibly around that flow. Relatedly (but not exactly identical) communication devices (mobile phones, radios, etc) manipulate high frequency electromagnetic waves (radio frequency radiation) to transmit their signals (sound, data video etc) (more on that next month!!). Don’t let the term 'radiation' frighten you, as the scientific use of radiation simply refers to energy radiating from a source (not specifically the nuclear stuff!) Think of the radiator on your wall radiating heat energy radiation, for example.
These forms of electro-magnetism have always been around us. The earth is magnetic (this is the basis of the magnetic compass) and that electromagnetic field protects us on earth from a variety of harmful particles emitted by the sun which would otherwise be fatal to all life on earth. Radio signals are generated by astronomical bodies and bathe our planet constantly (the basis of radio astronomy). Static electricity and thunderstorms also generate a variety of different types of currents and fields. Obviously there has been a big increase in the types of fields around us as we become more dependent on technology.
Where have fears about cancer risks with power lines come from?
Mains electricity in our homes is usually at 220V. However, to transmit the amounts needed for cities, electricity must be transmitted at much higher voltages, thousands of times higher, through bigger cables. The fields around such cables are likewise somewhat stronger (albeit that strength falls off very dramatically with small differences in distances from the cable). The effects of such fields can be in part visualised with fluorescent tubes placed at ground level immediately under them (see a cool video of this).
Some years ago, researchers looking at geographical patters of cancer diagnosis found some evidence of a small increase in the rates of rare childhood blood cancers (but not other forms of cancer) among some, but by no means all, communities living close to power lines. The rates of other cancers were unchanged. These findings spurred further interest into whether the EMF might be causing this small increase in childhood leukemias. Similar findings were also seen internationally around some nuclear reprocessing plants but not nuclear power plants.
Initially, lots of different mechanisms were proposed as to how EMF might contribute to this small increase in children’s cancer numbers. Decades of analysis has now shown that these cancers occur where rural populations rapidly mix with more urban or “new” groups of people. In other words, lots of new people come into smaller, isolated communities. This in part explains why the findings were sporadic. Mixing tends to happen around new industrial projects located in rural areas and in specific patterns of the countryside as cities spread.
This population mixing can introduce largely insignificant infections (mostly viruses) into these groups of people. These infections in combination with certain mutations found to occur occasionally in the immune systems of children, can lead to a proportionately temporary (few years) increase in rates of blood cancers among children. Once these infective agents become part of the background of infections for such communities, the rates of childhood blood cancers fall back to the national rate.
So while initially there were some concerns that there could be a small increased risk of more children’s cancers occurring around powerlines, we now know that it’s not due to electricity.
Please see this article in Nature and this article in the British Journal of Cancer for some more background.
In Part 2 next month, we’ll look at what research says about the related area of cancer risk with communications masts, mobile phones, Wi-Fi, etc.