Sunday, June 19, 2011

US researchers find excessive TV viewers are at higher risk of death, diabetes

Another rubbishy meta-analysis. No systematic control for social class, in other words. All they have found is that middle class people watch less TV and middle class people are healthier generally

PEOPLE who watch excessive amounts of television are at higher risk of diabetes, heart problems and early death, a comprehensive review has concluded.

US researchers analysed a range of studies published in the past 40 years and found too much television really can kill you. The results of the meta-analysis performed by scientists at the Harvard School of Public Health are published in the June 15 issue of the Journal of the American Medical Association.

More than two hours per day of TV-watching increased the risk of type two diabetes and heart disease, while more than three hours a day boosted a person's risk of dying prematurely.

Each two-hour increment in viewing per day was linked to a 20 per cent higher risk for type two diabetes; a 15 per cent increased risk for fatal or nonfatal cardiovascular disease; and a 13 per cent higher risk for all-cause mortality. "While the associations between time spent viewing TV and risk of type two diabetes and cardiovascular disease were linear, the risk of all-cause mortality appeared to increase with TV viewing duration of greater than three hours per day," the study said.

The habit of plunking oneself down in front of the television and watching for hours makes up about five hours of daily activity on average in the United States, but is also a prevalent practice around the world.

In Europe, people spend about 40 per cent of their daily free time, or three hours, in front of the tube, and in Australia the average is 50 per cent of daily free time or four hours, the study said.

"The message is simple. Cutting back on TV watching can significantly reduce risk of type two diabetes, heart disease, and premature mortality," said senior author Frank Hu, professor of nutrition and epidemiology at Harvard.

"We should not only promote increasing physical activity levels but also reduce sedentary behaviours, especially prolonged TV watching."


Cellphones are unlikely to cause cancer because brain tumours are not clustered within the radiation range emitted from most devices

The debate over exactly how dangerous mobile phones are to users took a fresh twist today with the publication of a fresh report. Researchers from the University of Tampere in Finland have directly contradicted recent findings from the World Health Organisation.

The Finnish report says mobile phones are unlikely to cause cancer because brain tumours are not clustered within the radiation range emitted from most devices, a new report finds.

However the WHO warned for the first time that mobile phones may cause cancer and have urged users to limit their use. The warning came following Interphone's research from 13 countries that found that even just using a phone for 15 minutes a day could substantially increase the risk of a brain tumour. And that according to their researchers they say it could take 15 to 20 years for primary cancers to develop.

Researchers in Finland however contradicted that report and found people who spent the most time on mobiles were no more likely to experience tumours located within five centimetres of the phone, where '90 percent of the radiation' is emitted.

Their results back up an earlier study at the University of Manchester who found that there has been no change in the rates of the disease - despite 70 million phones being used in the UK.

Today's findings from the University of Tampere in Finland were revealed as the World Health Organization announced that, upon review of available scientific evidence, mobile phones should be classified as 'possibly carcinogenic.'

Study author Dr Suvi Larjavaara said although the results may be reassuring, they are certainly not conclusive. She said cancer could take a long time to develop and only five per cent of the people included in the study had been using mobile phones for at least 10 years.

Larjavaara acknowledged that these latest findings contradict the WHO's latest announcement, which placed mobile in the same cancer risk category as coffee and chloroform.

Last year, a study including 13,000 mobile users over 10 years found no clear answer on whether the handsets cause brain tumors. However, another study from last February suggested that using a mobile phone can change brain cell activity.

Use of mobile phones has increased hugely since their introduction in the mid-1980s. About five billion mobile phones are currently in use worldwide.

One issue that arises when studying the risks of phone use is that people often don't recall how much time they spend on the phone.

Larjavaara and colleagues decided to look at the location of tumours, reasoning that an excess of tumours close to the phones would implicate the devices. Ninety per cent of the radiation released from phones is absorbed by the brain tissue located within five centimetres of the handset.

Researchers mapped the exact location of 888 brain tumors diagnosed between 2000 and 2004 relative to where people would hold their mobile while talking. They found no correlation between the two. The study was published in the American Journal of Epidemiology.

However, another scientist who has also performed studies on long-term mobile phone users advised caution about the results. Dr Elisabeth Cardis from the CREAL-Center for Research in Environmental Epidemiology in Barcelona, said the definition of exposure 'is overly simplistic, in my opinion.'

She said previous studies have found that the most exposed area is generally located around the ear. 'I expect there is substantial misclassification of exposure in the analyses published in the American Journal of Epidemiology, and hence it is not possible to draw conclusions about the presence or absence of a risk,' she concluded.


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