Cell phones, cancer, and press release abuse

The Daily Express reports

MOBILE USE IS LINKED TO BRAIN TUMOURS

LONG-term mobile phone users could face a higher risk of developing cancer in later life, according to a decade-long study.

The report, to be published later this year, has reportedly found that heavy mobile use is linked to brain tumours.

The survey of 12,800 people in 13 countries has been overseen by the World Health Organisation.

Preliminary results of the inquiry, which is looking at whether mobile phone exposure is linked to three types of brain tumour and a tumour of the salivary gland, have been sent to a scientific journal.

As I write, a google search could locate no news or science source more detailed than this Daily Express article. Note that:

1. This is not peer-reviewed study. The results are only "preliminary" and have merely been "sent to a [unspecified] scientific journal."
   
2. It is said that the study was done for the World Health Organization but no specific authors/scientists are mentioned.
3. It is not specified what statistical standards were used or which cancers they claim correlations for.
   

In sum, this is not even information to begin to evaluate the results. News reports like this should never be published.

It is normal for statistical-medical studies to produce the occasional false result. So, statistical studies generally should not be believed until they are confirmed by independent studies. For such cell-phones-cause-cancer claims, despite all the scare headlines in newspapers, there has been no confirmation.

The UN uses a similar press-release technique for hyping global warming. First, they release a press summary with no supporting data. The press accepts the frightening conclusions uncritically. The full report is not released until many months later and, by the time it can be evaluated, the press has moved on to the next scare story.

Mobile phones may be death sentence?

Are mobile phones "more dangerous than smoking or asbestos"? So says Dr Vini Khurana in a study currently being hyped. His claim is that there is a brain cancer risk for long-term, 10 years or more, use of cell phones. This would be important, if true. What is the status of this research? The Independent (UK) writes:

[A] paper based on the research is
currently being peer-reviewed for publication in a scientific journal.

In other words, his claims have not yet gotten through even the first stage of scientific validation. His calling of press conferences to scare the general public on something that has not survived peer review is irresponsible.

Statistical studies claiming to link some action to some disease should never be believed until confirmed by other studies. It is the nature of statistics, discussed in detail here, to go wrong occasionally. If there is a genuine link between 10-years of cell phone exposure and certain malignant brain tumors, it will start to show up consistently in future studies. At the moment, one study links cell phones to one awful disease and the next study links them to some other awful disease. This is exactly the statistical pattern that one would expect if there were no link at all.

Cell phones cause cancer?

The BBC writes in bold type about an Israeli study by Dr. Siegal Sadetzki:

Heavy mobile phone use may be linked to an increased risk of cancer of the salivary gland, a study suggests.

That sounds frightening but, buried deep in the story, the BBC writes that a bigger study contradicts it:

Despite these latest findings, the largest and longest-running investigation ever to be carried out into mobile phone usage found no increased risk of any sort of cancer.

It followed 420,000 people in Denmark, some of whom had been using a mobile phone for as long as ten years.

There was in fact a lower incidence of cancer than expected in a group of that size, suggesting mobile phones had no impact on the development of tumours.

One important point about all such studies that scientists know, but the news media doesn't explain, is that the results of statistical studies are statistical, that is, somewhat random. The usual scientific standard is to report results at the 95% confidence level. Now, suppose, for the moment, that there is absolutely no connection between cell phones and cancer. Then, perform tests for the correlations between 20 different types of cancer and cell phone usage. At the 95% confidence level, odds are that one of those twenty test results will be wrong. (This is because 1 out of 20 is 5% and 5% is the expected error rate on tests done to 95% confidence.) To be clear, that one wrong result does not mean that the scientist did anything wrong: As scientists well know, it is simply the nature of statistical studies. What happens next, of course, is that the news media will write a headline based on that one result.

Next, that scientific group or another does another, say, 20 tests for correlation. Still assuming that there really is no connection, only (about) one of those tests will be positive for a connection. It will likely, by random chance, show a connection, though, to a different cancer. That new (wrong) result will get another headline in the news media.

So how do you tell the difference between valid and incorrect results in such studies? It is simple: if several studies show a link to the same cancer, the result is likely valid. If successive studies show links to different cancers, then each of those results is likely to be merely a statistical fluke. Since, so far, successive studies give different results on cell phone and cancer, as in the two studies mentioned by the BBC above, the reasonable conclusion is that we are looking at statistical flukes.

The second key issue with these studies is that they find only correlations but not causality. The Israeli study, for example, found that the increased cancer risk was associated with heavy cell phone users who live in rural areas. It could be, if the statistical result is true, that the salivary gland tumors have nothing to do with cell phone usage and are instead caused by exposure to, say, cow manure or other chemicals common in rural areas where, maybe, landlines are absent so cell phone use is more common. Issues like that could be sorted out by future statistical studies. (It is likely that, as good scientists, Dr. Sadetzki or her colleagues are already working on such kinds of issues.)

So, for the time being, there is no reason to think that tinfoil hats are necessary.

PREVIOUSLY, I have discussed cell phone radiation issues here and here.

UPDATE: This Israeli study is now featured at Slashdot, Information Week, and the (London) Telegraph. Information Week does a good job of putting perspective on the alleged risk level

Cell phone wrecks sleep, maybe

The Independent (UK) has a story running under the title "Mobile phone radiation wrecks your sleep." They write:

A massive study, following 1,656 Belgian teenagers for a year, found most of them used their phones after going to bed. It concluded that those who did this once a week were more than three times – and those who used them more often more than five times – as likely to be "very tired".

If we accept the Independent's description of the study at face value, this only says that frequently carrying on conversations after going to bed leads to being "very tired." To identify the cause as cell phone usage, the researchers needed to compare those who talk too much by wired phone to those who talk too much by wireless (cell) phone.

Seeing only what you want to see

Dick Meyer, the editorial director of CBSNews.com, explains Sen. Obama's appeal:

Sen. Obama is a Rorschach test. I see hope! I see brains! I see a whole new kind of politician! I see an amazing life story! I see an orator! I see a natural! I see a hero!

Well, real people aren't Rorschach tests. They aren't blank slates. And by January 2008, Senator Blank Slate, D-Ill., will be a messy chalkboard.

Seeing what you want to see ("a Rorschach test") is common in politics.

A news story that appears to me to be as much a Rorschach test as Sen. Obama is the disappearance of some colonies of bees, dubbed "Colony Collapse Disorder." Some reporters claim the cause is "global warming." Some blame "cell phone radiation." Others blame genetically modified crops. What all these explanations have in common is only that they represent currently popular liberal anxieties. More plausible explanations, such as a new virus (plagues are as old as history), do not appeal to liberal imaginations.

Continuing on the subject of presidential candidates, but touching on a separate theme, Dick Meyer also writes

So tell me how you're feeling about Mrs. Clinton and Mr. Obama. Because I think you are in denial about some very important issues your fellow citizens have in their relationships with these two potential parent figures. [emph. added]

Here we see yet another appearance of the bizarre president-as-parent analogy which is just one member of a larger group of childhood analogies.

Hat tip: Dr. Helen.