Mobile Phones may be a Carcinogen

November 12, 2012

Mobile Phones may be a Carcinogen

It has been widely reported in the media that mobile phones may cause cancer. The Daily Mail takes a stronger line and states that after many years of deliberation the health sector has stated ‘an authoritative verdict’ concerning the risks mobile phone users subject themselves to.

The International Agency for Research on Cancer (IARC) has been formed ‘to coordinate and conduct research on the causes of human cancer, the mechanisms of carcinogenesis, and to develop scientific strategies for cancer control’. It is a division of the World Health Organization (WHO), and it studied the area of mobile phones and the risk that they may promote cancer developing in a body. After conducting its study the IARC stated that mobile phone signals may be ‘possibly carcinogenic’. The main reason for this classification was ‘limited evidence’ of an association with some types of brain cancer. But this does not suggest a link with any certainty and the IARC also says that external factors could have distorted the findings in addition to no link being found to other types of cancer.

To clarify, this area must be further researched but based on the results of the present study there may be some link between mobile phone usage and brain cancer. The results from the initial study indicate that this field must be subjected to additional vigorous scientific research.

Mobile Phone Classifications

The IARC has a classification table to grade substances and exposures by their likelihood to cause cancer. The IARC classification group 2B for mobile phones means that ‘there is a possibility that they cause cancer in humans’.

The full IARC scale is seen below:

Group 1: is used when there is ‘sufficient evidence of carcinogenicity’ in humans.

Group 2a: an agent is ‘probably carcinogenic to humans’.

Group 2b: an agent is ‘possibly carcinogenic to humans’.

Group 3: an agent is ‘not classifiable as to its carcinogenicity to humans’.

Group 4: an agent ‘is probably not carcinogenic to humans’.

Substances and activities that would be in group one include smoking and asbestos. In group 2a the evidence in animal studies is ‘sufficient’ but ‘limited’ in humans to warrant such a high classification. Group 2b shows limited evidence in humans that it may cause cancer and the findings from animal studies is ‘less than sufficient’. Mobile phones fall into this classification. If the substance or activity is in group 3 then the evidence is inadequate and limited in humans and animals.

Why This Classification and Why Now?

The IARC classification was made by a working group of 31 scientists from 14 countries in May 2011. The scientists based their decision on findings regarding potential carcinogenic hazards related to mobile phone usage throughout the world.

The working group assessed the evidence of linkages between phone users’ incidence of cancer and their phone usage habits. External factors such as other radio frequency exposure were also considered during the evaluation and discussions between the experts. This meant that any evidence of exposure to other sources of RF had to be identified, for example if someone worked with radar or microwave technology. Checks were also carried out to ensure that exposure to TV and radio signals was given due consideration.

The working group found ‘limited evidence’ of a link between two types of cancer and mobile phones. The two cancers were both associated with the brain and are called glioma and acoustic neuroma. The definition of ‘limited evidence’ was used because, in their view, there was an association between cancer and mobile phone usage but chance or bias could not be excluded with confidence. The evidence was inadequate to make any useful findings or draw a conclusion for other types of cancer. This was because all other scientific research previously conducted either lacked consistency, was of inadequate quality or had some other reason which did not permit the working group to draw a conclusion. Another reason may also be that there are presently no studies on humans available.

Dr Jonathan Samet, chair of the IARC working group, commented, ‘The conclusion means there could be some risk and therefore we need to keep a close watch for a link between cell phones and cancer risk.’ He also stated that additional research should be carried out into the long term heavy use of mobile phones.

Is this a Big Problem?

The working group indicated that the potential risk for heavy users had been quantified in one report. They said that people who used their phones for more than 30 minutes a day over a 10 year period showed a 40% increased risk for glioma brain tumours. However, because the actual chance of getting a glioma is pretty low anyway then a 40% increase still give a minimal risk. The actual figures according to Cancer Research UK are that a man has a 1 in 133 chance of developing any type of brain tumour. In women that chance is 1 in 185. Gliomas make up about half of the brain tumours in the UK and they can be broken down into four sub types. This means that the chance of getting a glioma is approximately 1 in 266 for a man. Depending on the sub type of the glioma the chance that one develops could decrease quite dramatically. If we assume that the chance of a man developing a glioma is around 1 in 500 then increasing the chance of contracting one by 40% still means that the man has a 1 in 300 chance. Still very low, however IARC feel that there may be an indication of increased risk. But IARC’s classification does indicate that although some evidence may be present that this evidence is not robust enough to draw strong conclusions.

Studies

Although there have been studies into mobile phones and their perceived link with cancer the experts complain that the quality and academic rigour applied has been lacking in too many cases. They also point out that the majority are case control studies. This means that people with cancer (case) are compared with people without cancer (control) and then their mobile phone habits are analysed. They point out that longer term studies across the population are needed to make meaningful findings.

In their view only one study has been satisfactory. That took place in Denmark and assessed data from 420,000 people. These were a cross section of the population and the survey was long term and found no link between cancer and mobile phone usage. In the United Kingdom, Cancer Research UK stated that no study within the last 10 years had found any link between mobile phone usage and any type of cancer.

The findings do not reach statistical significance in many studies. One study found that mobile phones did increase the risk of cancer; however another 13 found no evidence to suggest that there was a link. When all of the results are aggregated then the suggestion is that there is no link between mobile phones and cancer.

Cancer Research UK also indicate that many studies are not comparing like with like. The advances in technology have meant that patterns and power levels of the RF energy are no longer the same as before. Studies do not clarify what model or technology the users’ phones are. And because many of the studies require the participants to remember what their phoning habits from years before further reduces the reliability of the study.

It is further stated that mobile phone usage worldwide is reported to be around 5 billion people. And yet no increase in the number of cancers seen is noted. If there was a major issue then if the records of incidence of cancer since mobile phones began were tracked then a corresponding increase in cancers should have been seen. No trends have been noted, however it must be remembered that many types of cancer can take many years to develop. Cancer Research UK goes on to say that the IARC’s group 2B in their view should mean that, ‘there is some evidence for a risk but it’s not that convincing’.

How might mobile phones cause cancer in the body?

The exact method used by mobile phones which may increase the risk of cancer is still unknown. Cancer Research UK say that although mobile phones give off microwave radiation it is at such a low level it is thought to be incapable of damaging our DNA. Typically the microwave energy transmitted is millions of times less than an X-ray.

Because of the unknowns the WHO has advised people to use hands free devices or texting to further reduce any possibility of a risk. In the UK, the Department of Health has no concerns presently. However it does say that because younger people under 16 years still have bodies which are developing then they should limit mobile phone usage. Again it is unknown whether the body or nervous system in a younger body can more easily be affected but precautionary behaviour is encouraged.

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