The potential harm from microwave radiation (MWR) given off by wireless devices, particularly for children and unborn babies, is the highlight of a new review.
Although the data are conflicting, links between MWR and cancer have been observed.
The review, by L. Lloyd Morgan, senior science fellow at Environmental Health Trust, and colleagues, was published online July 15 in the Journal of Microscopy and Ultrastructure.
The authors reviewed the current literature showing that children face a higher health risk than adults. They looked at peer-reviewed cell phone exposure studies from 2009 to 2014, along with cell phone radiation data, government documents, manufacturers' manuals, and similar publications.
Children and unborn babies do face a greater risk for bodily damage that results from MWR given off by wireless devices, according to Morgan and colleagues.
The rate of MWR absorption is higher in children than adults because their brain tissues are more absorbent, their skulls are thinner, and their relative size is smaller. Fetuses are particularly vulnerable, because MWR exposure can lead to degeneration of the protective sheath that surrounds brain neurons, they report.
Multiple studies have shown that children absorb more MWR than adults. One found that that the brain tissue of children absorbed about two times more MWR than that of adults, and other studies have reported that the bone marrow of children absorbs 10 times more MWR than that of adults.
"Belgium, France, India, and other technologically sophisticated governments are passing laws and/or issuing warnings about children's use of wireless devices," the review authors write.
They write that MWR exposure limits have remained unchanged for 19 years. They also note that smartphone makers specify the minimum distance from the body that their products must be kept so that legal limits for exposure to MWR aren't exceeded. For laptop computers and tablets, the minimum distance from the body is 20 cm (about 7.8 inches).
The authors explain that current exposure limits were set up based on the wrong assumption that tissue damage from overheating is the only potential danger of wireless devices.
But extensive scientific reports have detailed non-heat-related effects from long-term exposure. Although government warnings have been issued worldwide, most of the public is unaware of such warnings, they write.
"There are toys being sold to infants and toddlers that are dangerous," Morgan says. "The risk from exposure to any carcinogen is higher in children, and the younger the child, the higher the risk.
The review authors "continue to raise appropriate concerns related to the ever-increasing role of technologies that emit nonionizing radiation, including cell phones and certain toys," says L. Dade Lunsford, MD, professor of neurological surgery at the University of Pittsburgh. Lunsford was not involved in the study.
"They indicate that certain types of tumors, at least as reported, may have increased in incidence, including the most malignant brain tumors and perhaps hearing nerve tumors," he tells Medscape Medical News. But he says there are issues with some of the data, and that many of the reports are anecdotal. Also, it's unclear whether the perceived increase in tumors may be due to better diagnoses at earlier stages, he says.
The potential health risks related to cell phone use, especially brain tumors, have remained a hot-button issue. Studies have been inconsistent and results have been conflicting. There is no consensus about the degree of cancer risk posed by cell phone use, if any at all.
Take-Home Messages About Safe Use
Wireless devices are now part of everyday life, "but they can be used in a manner that is safe enough," Morgan says.
Morgan and his colleagues have made some recommendations.
The first is that "distance is your friend." He says holding a cell phone 15 cm (about 6 inches) from your ear "provides a 10,000-fold reduction in risk."
Unless a cell phone is turned off, it is always radiating. When not in use, it should not be kept on the body. The best place for a cell phone is somewhere like a purse, bag, or backpack.
Devices should be kept away from a pregnant woman's abdomen, and a mother should not use a cell phone while nursing, Morgan says. "And baby monitors should not be placed in an infant's crib."
Children and teens need to know how to use these devices safely. Cell phones should not be allowed in a child's bedroom at night, he says. "The Pew Research Center has reported that 75% of preteens and early teens sleep all night with their cell phone under their pillow."
"Boys should not keep a cell phone in their front pants pockets," he says. There is a potential harm to sperm, although no studies of young boys have determined whether or not early exposure to MWR has any effect on sperm after puberty, he says.
"And girls should not place their cell phone in their bras," he says. This recommendation was based on a case study of four young women with a history of putting cell phones in their bras, and who developed breast cancer -- two at the age of 21.
Because the risk snowballs, and more radiation is absorbed with more hours of use, children should be taught to use their wireless phone as little as possible, Morgan says. Landlines, Skype, and computer phone services (when connected to the Internet with a cable) don't give off radiation, and parents should encourage their kids to use those.
Finally, Wi-Fi routers in the home should be placed away from where people, particularly children, spend the most time.
The authors note that some studies have shown an increased risk for brain cancer with cell phone use, although some of these data have been disputed. In recent years, glioblastoma (a type of brain tumor) rates have increased in Denmark and the United States, and brain cancer incidence has increased in Australia, according to data drawn from cancer registries. The average time between exposure to a carcinogen and the diagnosis of a resulting solid tumor is 3 or more decades, so it will likely be several decades before tumors induced by childhood MWR exposure are diagnosed, they write.
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