A recent study could change the debate over cell phones and cancer. A research group has reported a sharp increase in the incidence of parotid gland tumors over the last 30 years, with the steepest increase happening after 2001.
The research was carried out at Hebrew University in Jerusalem at the Hadassah School of Dental Medicine by Rakefet Czerninski, Avi Zini and Harold Sgan-Cohen.
For many years now, skeptics have argued that the epidemiological studies pointing to a tumor risk from cell phones must be wrong, because no one has seen an increase in cell-phone related tumors in the general population.
But one of these earlier epidemiological studies found that heavy users of cell phones "showed significantly elevated risks" of parotid gland tumors. (Sadetzki et al showed 49 percent increased risk of parotid gland tumors. Another, by Lonn et al, in 2006, found parotid gland increase of 160 percent (borderline significance).
So the long- term trend data recently reported by Hebrew University is not surprising.
According to Microwave News:
"The parotid gland is a type of salivary gland -- the one that is closest to the cheek next to where most people hold their cell phones. Interestingly, the new ... data show no similar increases in the two other major types of salivary glands, the submandibular and sublingual glands that are further away from the phone."
In related news, another study by Hardell et al in Sweden has confirmed that design flaws in the Interphone study (published May 2010) caused the risk of brain tumors (gliomas) to be underestimated.
The Interphone study claimed that use of a digital cell phone for more than 10 years led to a 118 percent increase in the risk of brain cancer. But an analysis by Hardell et al in 2006, which experts consider a very well designed study, revealed that the increased risk of malignant brain tumors could be as high as 180 percent.
A recent re-analysis of the Hardell data by the Hardell team, published December 17, 2010 in the International Journal of Epidemiology, finally now explains the difference in brain tumor risk found in the two studies.
It shows the difference to be related to differences in methodology: 1) a difference in the age ranges selected for the two analyses, and 2) due to the Interphone study inaccurate classification of portable phone users as 'unexposed' to microwave radiation.
When the Hardell data was recast by the Hardell team using the more limited protocol used by the Interphone study -- i.e. considering subjects who were between 30-59 years instead of 20-80 years used by the Hardell team originally, and classifying any subject who used a cordless phone as 'unexposed,' as the Interphone study had inexplicably done -- the two data sets revealed essentially the same risk of brain tumors.
This demonstrates the lesser risk of brain cancers from cell phone use reported in the Interphone study was a result of the Interphone study's design flaws.
Camilla Rees of ElectromagneticHealth.org says:
"Were a wider age range used, as in the original Hardell research (ages 20 to 80), and subjects properly classify as 'exposed' to microwave radiation if they used portable (including cordless) phones emitting microwave radiation, the risk of brain tumors would be as was found in the original Hardell research: a 180% increased risk of malignant brain cancers."