Canada: Moleculair bioloog over te grote blootstelling aan mobiele telefonie.

Dr. Richard A. Stein, moleculair bioloog aan Princeton University, geeft in een interessante bijdrage zijn mening in het gezondheidsdebat over te grote blootstelling aan mobiele telefonie. Maar voor ingenieurs en natuurkundigen is dit heldere artikel waarschijnlijk aan dovemansoren gericht:

Bron: LFP press 5 juli 2010

Comment
Overexposure to cellphones hazardous to one’s health

By RICHARD A. STEIN, Special to QMI Agency

One of the most fervent and important debates in modern society is the one surrounding the health effects of wireless technologies. Perhaps no other topic has polarized society so much in recent history, except for the tobacco saga.

While in 1939 the German physician Franz Hermann Muller published the first epidemiological study linking smoking to cancer, and two 1950 articles in the Journal of the American Medical Association linked smoking to cancer, cigarette ads continued for decades, featuring health professionals, babies, and even Santa. It took thousands of scientific studies until establishments that initially adamantly refuted any links admitted to the potential health dangers.

Exposure to wireless technologies has become ubiquitous -- through cellphones, wireless Internet, Bluetooth, and other applications. But how much do we know about the impact radio frequency radiation emitted by wireless devices has on biological systems?

The much-anticipated Interphone study published on May 18, 2010, in the International Journal of Epidemiology, which received 5.5 million euros in funding from the same wireless industry whose product it proposed to examine, abounds in discussions about bias and statistical significance -- and is confusing. Even more confusion is present in many media reports about the article.

Interestingly, Table 2 of the article's appendix, which is part of the paper but is not included on the journal's website and was not broadly distributed and discussed in press releases, reveals the risk of glioma, a brain tumour with a dire prognosis, is more than twice as frequent in people who used cellphones for more than 10 years and among heavy users.

''Heavy use'' in this study entails approximately 26 minutes a day. Most people would not consider 26 minutes to be ''heavy.'' I would envision this at the low end of my cumulative daily exposure.

Many press releases and interviews emphasized that, unlike X-rays and gamma rays, which are known as ''ionizing radiation'' capable of breaking the double-stranded DNA and causing cancer, ''non-ionizing radiation'', such as the one emitted by cellphones, does not have sufficient energy to break DNA and cannot cause cancer.

Not so fast. Too many assumptions are lumped together. While the energy of non-ionizing radiation is not sufficient to directly damage DNA, every known environmental perturbation can act directly or indirectly - or, sometimes, by combined mechanisms.

All cells in all living organisms contain tens of thousands of different proteins that govern biological processes. One special class of proteins, known as heat shock proteins or chaperones, assists other proteins in adopting their structure and functioning adequately.

Many authors have demonstrated that radio frequency radiation of the type emitted by cellphones severely affects heat shock proteins, ultimately affecting cell division. Most importantly, this effect was shown to be a ''non-thermal effect'' -- it does not require the heating of tissues.

Safety guidelines in many countries assume ''thermal effects'' are the only possible mechanism by which cellphone radiation could cause damage, yet an abundance of scientific articles reveals biological perturbations caused by radio frequency radiation without the need to heat tissues.

Another non-thermal effect that was demonstrated for radiation emitted by cellphones is protein leakage through the blood-brain barrier, which severely impairs the proper functioning of the nervous system. Cellular damage was also observed in the sperm of men carrying mobiles in the back pocket, and independent studies demonstrate significant correlations with infertility, decreased sperm counts, viability and mobility. Several authors advised men of reproductive age to avoid keeping mobiles in receiving mode below waist level.

The preponderance of peer-reviewed studies reveals serious reasons for concern. Several countries have already issued advisories and prohibit the sale of wireless devices to children under 16, who are even more susceptible to radiation.

The Interphone study, speckled with uncertainties, shows one thing for certain: after some time, cellphone usage causes cancer. Further research is essential to better define this time frame, which most likely differs among individuals.

The mere fact cellphone booklets warn to keep the device at a certain distance from the body is one of the strongest indications that the radiation emitted is not totally harmless. As with every exposure, some individuals will be less sensitive, other will be more sensitive, but the mere warning shows something is going on.

While we need our cellphones, we also need to be aware of the health hazards. It is time to revisit our love story with wireless devices to ensure a long and healthy relationship in each other's company.

This column is not the opinion of Princeton University.

Richard A. Stein, MD, PhD, is a post-doctoral research associate in the Department of Molecular Biology at Princeton University in Princeton, N.J.

Voor het originele artikel zie:
www.lfpress.com/comment/2010/07/02/14587546.html .



Lees verder in de categorie Berichten Internationaal | Terug naar homepage | Lees de introductie