09/12/2010 - Mobile phones' effect on child behaviour
The latest research to receive high profile attention in the British national press is a paper studying the affect of pre- and post-natal exposure to mobile phones on young children. The primary author published the only other paper on this issue in 2008, finding that both exposures were associated with an increase in misbehaviour in the children by the age of 7. This association was particularly marked with prenatal exposure (mother's exposure whilst pregnant with the child).
The paper originally received a number of criticisms, from difficulty to ascertain accurate exposures and a number of other data confounders, to the lack of plausible mechanism. As a result, the same authors set about replicating their work, with over twice the number of children and a number of improved controls to handle some of the remaining confounding issues. Their findings? The increase in effect was slightly smaller than the previous paper (a 50% increase rather than an 80% increase) but, because of the increased number of children, the confidence interval was much tighter and very statistically significant.
The authors very modestly summarise the findings offering to the current literature by stating in their "What this study adds" section:
There is an association between prenatal as well as postnatal use and behavioural problems by age 7 years among a general population of mothers who are cell phone users. These results replicate the findings of an association observed among only early technology adopters. These new results also reduce the likelihood that these are chance findings or findings that did not adequately consider the influence of other important factors for behavioural problems. These results should not be interpreted as demonstrating a causal link between cell phone use and adverse health effects for children, but if real - and given the nearly universal use of cell phones - the impact on the public health could be of concern.
Leeka Kheifets, secondary author and known figure in the ELF / powerlines and health debate, has made some excellent comments with regards to the paper's contribution: "These new results back the previous research and reduce the likelihood that this could be a chance finding ... Although it is premature to interpret these results as causal, we are concerned that early exposure to cell phones could carry a risk, which, if real, would be of public health concern given the widespread use of the technology." These comments are cautious but well reasoned and we applaud them, particularly from someone who we have considered to have understated the evidence strength in ELF work in the past.
This is all pleasantly understated, including their comments in the Telegraph, and highlight the potentially large burden of risk without overstating the case, yet it still received a strong counter by Prof Pat McKinney, Emeritus Professor at the University of Leeds, with a number of equally overstated and unsupported points in the opposite direction: "There is no scientific basis for investigating exposure of the growing baby when pregnant mothers use a mobile phone, as exposure to radiofrequency radiation from mobile phones is highly localised to the part of the head closest to the phone; there is no evidence to suggest that other parts of the body, such as the abdomen where the baby is growing, are affected by mobile phone use. We also have no evidence that a pregnant mother's behaviour is related to her mobile phone use and thereby affecting her baby. The risks linked to prenatal exposure are therefore questionable."
Our response to this is, overall, that two studies is still far too little to draw any concrete conclusions from. However, it is clear that the authors found an association even after increasing the quality of the study, and that if true this would be an area of considerable concern. To say "there is no scientific basis for investigating exposure" is nonsense - mobile phone and child misbehaviour have both considerably increased over the same period of time, so it's easy to make a theory that one may have an impact on the other. When a pilot study designed to compare users to non-users (with 13,000 participants no less) finds a strongly statistical association, the scientific basis is established - understanding why the association exists is the purpose of further research, it's not required for a scientific basis for investigation. It also is not unreasonable to theorise that maternal exposure may affect something in the mother that in turn affects what is passed through to the foetus, for example hormone production. As a result, the foetus' exposure to RF directly may indeed not be relevant, so dismissing it is logically false.
Of course, that's not to say that this is now a causal relationship demonstrating definitive harm, but this is the sort of paper that should encourage researchers in similar fields to want to investigate more deeply, not dismiss out of hand as being implausible and unworthy of serious consideration. The purpose of science is to uncover truths and then doggedly pursue them, and it casts a poor light on a respected professor to make such public statements - if the association turns out to be causal, the health impact on the current generation will be potentially enormous, and it is against the spirit of scientific investigation to do anything other than encourage serious and urgent further research to replicate this work.
- View story on the Telegraph website
- Other coverage on Doctor's Lounge
- Other coverage in The Metro
Divan H et al
, (December 2010) Cell phone use and behavioural problems in young children
, J Epidemiol Community Health (2010). doi:10.1136/jech.2010.115402 [View Author's abstract conclusions
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- View full story on Microwave News
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- View IARC's summary page of Monograph 98