Mobile phones don’t
cause brain cancer

Contrary to the claim in your Publisher’s Letter ("Mobile phones have increased risk of brain damage") in the June 2006 issue, there is no biological, medical or statistical basis to assert a link between mobile phone use and brain cancer.

Potential human health impacts of radio frequency energy have been studied in great detail over the past 50 years. This has resulted in a large body of scientific literature in this field, covering laboratory, clinical and epidemiological research.

Comprehensive reviews of 2200 research publications, including more than 410 studies specifically on mobile phones and base stations by governments and health authorities, continue without exception, to find there is no substantiated scientific evidence of health effects.

The UK research team of the largest study ever conducted on brain cancer and published earlier this year concluded: Overall, we found no raised risk of glioma (brain cancer) associated with regular mobile phone use and no association with time since first use, lifetime years of use, cumulative hours of use, or number of calls.

This study is part of a 13-nation INTERPHONE project coordinated by the International Agency for Research on Cancer (IARC). Once all the studies are completed, the IARC, an agency of the World Health Organisation, will do a combined analysis of the research which is expected to be published later this year.

From the results collected to date, the individual INTERPHONE studies, including the Swedish and UK studies mentioned in your letter, have all concluded there is no overall risk of brain tumours from mobile phone use. Your publisher’s claim that there is more and more evidence of a link is false and misleading. Moreover, it is inappropriate to selectively report non-statically valid results or partial results and not also provide overall results of these studies.

Once completed, it is expected that the INTERPHONE project will have examined 6000 cases of the two most common types of brain cancer – glioma or meningioma.

With regards to ear cancer, the researchers from the Denmark, Finland, Norway, Sweden and UK INTERPHONE project teams recently published their research involving more than 4000 people in the British Journal of Cancer and announced: The study found no relation between the risk of acoustic neuroma (ear nerve cancer) and the number of years for which mobile phones had been used, the time since first use, the total hours of use or the total number of calls, nor were there any relations separately for analog or digital phone use.

Regarding the Swinburne University of Technology study on brain function, the results from this study are inconsistent with previous research on brain activity and the small differences found could be due to normal biological variation or statistical noise. In fact previous studies have found an increase rather than a decrease in reaction times.

Over the past five years several studies looking at effects of mobile phones on human cognitive functions have been conducted by the Centre for Cognitive Neuroscience at the University of Turku in Finland with larger numbers of participants. These studies have not been able to replicate the results of the earlier smaller studies.

In relation to the effects of mobile phones on brain function, the World Health Organisation has said: These effects are small and have no apparent health significance. More studies are in progress to try to confirm these findings.

When studies find results which are novel, such as with this one, the well established scientific processes of replication and validation are required before the results can be accurately assessed within the whole body of scientific evidence.

The importance of replication has recently been demonstrated in Australia by the results of the research at Adelaide’s Institute of Medical and Veterinary Science (IMVS). The IMVS research could not reproduce the results of a 1997 pilot study that found digital mobile phone emissions doubled the cancer rate in genetically-engineered, cancer-prone mice.

Despite the disregard shown for this process in your Publisher’s Letter, the mobile phone industry continues to endorse the importance of sound, peer-reviewed and replicated research so that people can be assured of the safety of mobile phone technologies.

The gratuitous comparisons with the tobacco industry ignore the overwhelming body of evidence and have no place in a proper review of scientific fact. The health risks of tobacco are unequivocal, while there is a widespread consensus among international health authorities and governments that radio waves from mobile phones pose no known risks.

Your letter also raises the issue of driving and the use of mobile phones and the industry agrees that drivers should never take notes, look up phone numbers, read or send messages. This is an issue we take very seriously and the Australian Mobile Telecommunications Association (AMTA) has distributed widely its "Mobile Phones and Driving Safety Tips" (see www.amta.org.au/?Page=295).

Chris Althaus,
Chief Executive Officer,
Australian Mobile
Telecommunications Association.

Comment: if you read through the Publisher’s Letter carefully, you will note that there is no claim about mobile phone use and cancer but there is a link between mobile phone use and benign (ie, non-cancerous) tumours! In fact, we believe that since no link between mobile phone use and cancer has been clearly demonstrated, that allows the industry to continue to claim that there is no damage. We believe otherwise. For example, interested readers may care to have a look at www.newmediaexplorer.org/chris/2004/10/20/em_fields_on_brain_tumor_incidence_chemicals_and_cell_phones.htm

Nor have we made any gratuitous link between mobile phones and cigarettes, other than the two industries have used similar techniques of disparagement to nullify criticism.

Possible risk from cordless phones Your comment on brain damage from mobile phones is timely. There was much interest in this topic several years ago but things seem to have gone quiet in the intervening period. If one doesn’t use a mobile, then the alternative (immobile?) phone line to a local exchange may represent a similar hazard when accessed via the ubiquitous cordless phone. From the scant technical data for these phones, currently available units appear to employ similar frequencies and digital techniques to mobiles and are packaged similarly with close ear and head contact. As many of us engage in much longer conversations using a cordless phone than with a mobile, the cumulative effect may be equally damaging. Perhaps you have access to sufficient technical data to reassure cordless users of their safety. Otherwise, we may be persuaded to return to an old VHF cordless or plug in a corded phone. Andrew Hanby, Bingie, NSW.

Criticism of
early TV article

I was very interested to read your feature item "Television, The Elusive Goal" in the June 2006 edition of SILICON CHIP. I am not able to comment on the Australian part of the narrative as a whole, due to my lack of research, however I can inform you that on one aspect the article was in error. I refer to the use of a linear amplifier to increase the 10kW power output from the TV transmitters to 100kW ERP. No amplifier was needed or in fact existed for such a purpose; antenna gain was used, as is the present case. Note the numeric power qualification ERP (effective radiated power, not total radiated power).

Now I refer to the author’s comment about Mr J. L. Baird transmitting early TV across the Clyde (Scotland) – wrong! J. L. Baird worked for the Clyde Valley Electrical Power Company around 1916 as an assistant mains engineer, having been excused military service due to ill health. It was not until around 1923 that Baird began experimenting with selenium light cells with the possible application to television during 1923 in various places. Initially, experiments began in Guildhall St. Folkestone, to be followed by further experiments in Hastings (both towns are situated on England’s south coast). Baird did not transmit his early TV experiments but conveyed the signals by cable as raw video; at times telephone lines were used (post 1926). Following the Hastings experiments with the aid of one Victor Mills, it was reported that he moved to Tunbridge Wells and continued with his research until finally he moved to Soho in London’s West End where he "perfected his basic 30-line mechanical system".

The BBC under governmental directive transmitted 30-line TV signals from the London AM broadcast transmitter at Brookmans Park from 1929 until 1934 to a very limited audience. It was stated in your article that the BBC in 1937 proposed a solution to the system of TV to be adopted and it was: "A competitive demonstration to be held between the 240-line Baird system and the Marconi 405-line system."

First of all, it should be noted that the 405-line system was not the Marconi system but the EMI system developed under the leadership of Sir Isaac Schoenberg. Marconi developed the transmitter and antenna only and the two companies together formed a joint holding named Marconi-EMI. Thus the name "EMITRON" for the camera pickup tube, albeit a development of the ICONOSCOPE".

It is not true that the BBC decided to hold a competitive demonstration in 1937. The British government formed a committee titled "The Television Advisory Committee" (T.A.C.) to look into the progress of television development. Lord Selsdon chaired its first meeting on February 5th, 1935. It was a derivative of this committee and the British government that decided in 1936 to operate the two systems (Baird’s 240-line and Marconi-EMI’s 405-line) on a side-by-side trial for three months starting on November 2nd, 1936. The BBC provided the program content production and operators, while the respective equipment suppliers provided the technical expertise and managed the operation.

The T.A.C. had determined that the Marconi-EMI system would be chosen as the British TV system as early as January 4th 1937 – the last Baird system transmission was broadcast on January 30th, 1937. It is true that the BBC had representation on the T.A.C. along with the G.P.O.

The article also states that CRT tubes were known of before the beginning of the 19th century, again not a realistic statement when discussing TV. The only tube at the turn of the century was the Crookes tube, a laboratory curio that demonstrated the existence of cathode rays.

By 1902 Boris Rosing (Russia) had produced extremely crude still shadow images using a modified Crookes tube, again not TV. Braun (Germany) produced the first ultra-crude oscilloscope using a Crookes tube with an electron gun and electromagnets. It was not a high vacuum device and relied on ionisation of residual gases for its operation,. It had no heated cathode and at best may have supported a two or three-line TV system.

The first operational high-vacuum CRTs did not appear until about 1931 from Zworykin RCA and Manfred Von Ardenne Germany, with suitable colour and spot size tubes appearing in 1934. I know the article did not state that TV-type CRT tubes were available but the inference could be deduced by a non-technical reader.

That Zworykin of RCA had a complete all-electronic colour TV system is an example of journalistic license; the system of colour synthesis can hardly be called a complete colour TV system. A complete system must include capture, transmission, reception and display. Zworykin did not have such a complete system but just a basic patentable outline. Incidentally, Baird reportedly demonstrated and patented a working mechanical colour system in England during the late 1920s.

Despite this rather long-winded critique, I found the article to be most informative and interesting, taking me back on a wonderful nostalgia trip to my early days with ATN7 Sydney during the 1960s and early 70s.

Victor G. Barker, VK2BTV,
Gorokan, NSW.

Kevin Poulter comments: Regarding Baird transmitting across the Clyde (Scotland) I will talk to the elderly lady who told me her father helped Baird and see if any new light can be shown on the matter. Whilst she is elderly and not from a technical background, those were her very words.

Regarding the Marconi 405-line system, it seems that one reference book shortened Marconi-EMI to Marconi. Unfortunately some textbooks do have errors. The amount of space available for the article also prevented going into the detail given by Mr Barker.

Regarding CRT tubes, Mr Barker’s last sentence above says it all. We do not ask the wrong twist to be read into brief statements. I was incredibly impressed with the very early inventor’s creation and the similarity to much later TV tubes.

Fishing line fire sensor In the May issue, one of your readers wanted to know what sort of sensors could be used to detect an approaching bushfire. I am not sure but I think it was the CSIRO who used the following idea as part of their research about the rate of spread of bushfires. They used ordinary fishing line tensioned between two posts about half a metre above the ground. The fire burns through the fishing line, causing a weight or spring to be released. This is linked to a switch on a clock or data logger which records the date and time. One advantage of the fishing line method is that long sections can be easily monitored, even in heavy scrub. Disadvantages include false alarms from animals or falling branches. The fishing line may also deteriorate over time and snap from the constant tension. Ray Fitzsimon, Nambour, NSW.

Queries on digital
camera articles

In your March 2006 edition on page 11, it would have been good if there was a technical explanation given for the delay between "shutter" and capture. It seems strange that you can have an image on the electronic viewfinder but not be able to preserve that image at the instant the "shutter " button is pressed . . . or is that viewfinder only a subset of the picture?

In the same edition, on page 13, in the RGB, the B is meant to be Blue, not the Black as printed.

In the April 2006 edition on page 30, presumably the quote from the Japanese camera technicians was an April Fool’s joke. Otherwise the statement undermines the author’s credibility and should have at least attracted an editorial comment. Such inaccurate statements may be acceptable in a camera magazine but not in your publication which always gives (errors excepted) credible information.

In the April 2006 edition on page 35, a 70-210 acting as if it is 105-315 being "quite a long range" zoom is not correct; they are both the same in zoom range (which is the ratio of the longest to the shortest focal lengths) – ie, they are both 3X. Admittedly a significantly greater "telephoto" is achieved at 315mm equivalent.

Graham Goeby,
via email.

Kevin Poulter comments: The viewfinder image is not the actual image that is recorded, even in cameras with an electronic viewfinder. It is just a ‘thumbnail’ rendition. A camera may have this thumbnail or low-res image already in the viewfinder but digital cameras have a lag, or processing time, between the press of a shutter and actual exposure. This lag is the same (and therefore independent of) any shutter-speed.

Previously, lag was long enough to seriously miss action photographs (and still is, on economy models) but has now been reduced to acceptable levels in quality digital cameras. There are three lags, which I will generically call: (1) Booting on (at switch on); (2) Shutter to exposure lag; and (3) Processing and writing lag (titled "latent period" by some).

Lag, burst-rate and latent time are absolutely vital to sports and nature photographers. The author has two books by a world-renowned London-based digital photography lecturer that doesn’t even mention "lag time" once. Regardless, nothing is more important to an action photographer.

Latent time – the buffer memory capacity plus the write speed of cards – is another delay. It’s not widely known but like computer hard-drives, digital cards have a write speed, especially as many are micro hard-drives.

When more than one image is taken in close or very close succession, the buffer memory stores the image, to give the card time to process it and write it to the card. Processing includes altering the captured image to the owner-selected settings on the camera, like contrast, colour balance, colour saturation and sharpness. The buffer-memory ensures more photographs can then be taken, even though the last images are still being processed.

It’s still easy to reach the limit of this capacity, after a small number of high-resolution photographs in quick succession. In most instances, the more expensive the camera, the better this performance is. Unless you need "motor-drive" performance, this delay is not anywhere near as critical as the shutter lag-time.

When choosing a camera, it’s often best to download the instruction manual first and read it to see if it is right for you. Sometimes the best place to start reading any instruction manual is the troubleshooting section, as occasionally inherent flaws are admitted.

Do not accept "burst rate" figures that refer to low-resolution file sizes, if you do not intend to use the camera in low resolution. Some cameras specify, say, 30 frames with no write-time delay at low resolution but that’s deceptive if all the images are almost ‘thumb-nail’ low resolution and therefore too small for printing.

RGB is Red, Green and Blue, as correctly mentioned earlier in the article.

The quote from the Japanese camera technician was no joke. He was clearly referring to the digital camera computer’s inability to handle files other than those it was designed for, like any other computer.

And just like any other computer, it could cause a serious or terminal crash. It’s even inadvisable to load jpg images and cards formatted from other cameras. In fact, digital camera instruction manuals state third-party cards (ie, cards not the camera’s brand), are formatted by the camera before use.

"Quite a long range" (as opposed to "quite a long zoom range") referred to the degree of magnification of distant objects, the same as "range" refers to distance in other optics, like a weapon’s sights.

I believe these informal (albeit ambiguous) generic references have been used by camera enthusiasts for more than 40 years, referring to a telephoto lens as a long-range zoom and a wide-angle zoom lens as a wide-range zoom.

Certainly the magnification of the effective focal length of lenses due to the smaller size of digital sensors is a bonus. Lower shutter-speeds can be used before camera-shake blur of images occurs. Also, less expensive optic technology is needed to create a long (telephoto) zoom.

The only time when this effective magnification is not a bonus is when a very wide-angle lens is required. Then a super-wide, very expensive optic is needed, unless a composite panorama is taken. The author only has lenses to the equivalent of 28mm, preferring to save $1000 or much more on very wide-angle lenses. Instead, a very wide-angle photograph is achieved by taking two, or even three wide-angle images and joining them into a super-wide panorama. Often the result is clearer and less distorted as well.

The only downside – hours or even days of creative computer time are expended in Photoshop. The finishing touch – the ultimate final tweak – is deciding if any distortion to the final photograph will make it look even more like a true wide-angle photograph. Normally a slight stretch of the width will be appropriate.