HELSINKI, Finland, January 31, 2012–To evaluate the possible health effects of cell phone radiation, as with any other environmental hazard, scientists must consider different types of scientific evidence, including animal toxicology studies.
In sensu stricto animal toxicology studies, animals are exposed to a large overdose of tested chemical or radiation, beyond the levels normally encountered by human beings in real situations, and examined for any detrimental health effects. In another type of toxicology studies, animals are exposed to the potential hazard for their life-time and examined for the impact of the hazard on their health and on the health and development of the offspring.
However, in case of the studies of cell phone radiation, there is a limitation that precludes the use of toxicology to the fullest.
It is impossible to perform toxicology studies exposing animals to large overdoses of cell phone radiation. Large overdoses of cell phone radiation (microwaves) will heat animals, impacting animal health. Moreover, it is impossible to transfer this information to humans, because current cell phone safety standards are set at levels that do not cause heating.
What is the value of animal studies showing no effect for the human health risk analysis? It is very minimal, at the best. Certainly it is not proof of human safety.
Although humans and animals possess the same genes, the functions performed by these genes might differ between humans and animals. Some cancer types in animals and in humans are regulated by different genes. As a consequence, some of the cancers will appear in animals but not in humans and vice-versa.
This causes a very important limitation to evidence obtained from the animal toxicology studies of cell phone radiation.
If the exposed animals respond to the low dose cell phone radiation, then we may consider that people might also respond. This, however, does not automatically indicate a health hazard.
If the animals do not respond to the cell phone radiation, however, it does not automatically mean that people will not respond. No-effect-observed animal studies do not prove that the radiation is safe for humans.
Large toxicology studies performed in the past failed to detect any significant cell phone radiation effect on animal health. This does not prove that humans are safe and that the current safety standards protect all users.
Some smaller scale animal studies showed possibility of heath effects, such as carcinogenicity (leukemia) or induction of DNA damage. Another large animal study, conducted within the US National Toxicology Program (NTP study), is currently attempting to confirm or dismiss this information. The difference between the old and the ongoing NTP study is that the current research has much more reliable radiation exposure equipment and it also examines changes occurring on molecular level. Scientists expect to provide the results of the NTP study in a few more years.
From time to time, scientists publish the results of smaller animal studies and some grab the attention of the general public. A few days ago, a research group from Greece published a study that examined the effects of cell phone radiation and DECT phone radiation on the brains of mice using proteomics approach (proteomics examines hundreds or even thousands of different proteins in a single analysis). After exposure to radiation, scientists examined the mice brains for changes in levels of some 800 proteins.
Greek researchers concluded that both cell phone radiation and DECT phone radiation alters the amount of over 100 proteins in the brains of mice. They pointed out that the affected proteins are important in regulating learning, memory and in regulation of the processes leading to Alzheimer’s.
Unfortunately, the Greek study falls far from the target. The only thing that was somewhat shown is the possibility that cell phone radiation might alter levels of some brain proteins. The indication of the processes that might be affected was a pure speculation because the data obtained from the proteomic analysis were insufficiently confirmed. Certain proteins were named as affected but the confirmation experiments that the change is real were not performed (for those interested the more detailed analysis of the scientific content of the Greek study can be found here).
Take home messages:
- Animal studies that show no effect of cell phone radiation on health of animals do not constitute proof of safety for humans.
- Animal studies that show an effect do not prove health hazard, but only provide information of the directions of further studies in humans.
Read more from Dariusz Leszczynski in his science blog “BRHP - Between a Rock and a Hard Place” at http://betweenrockandhardplace.wordpress.com Dariusz is a Research Professor at the Radiation and Nuclear Safety Authority in Finland.
Follow Dariusz on twitter: @blogBRHP
Disclaimer: the opinions presented in this column are author’s own and should NOT be considered as the official opinions of the STUK - Radiation and Nuclear Safety Authority in Finland.
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