Studies so far do not show definitively that cell-phone use increases cancer risk, said the authors of the consensus statement issued on Tuesday by the WHO.
However, “limited” scientific evidence exists, they said, to suggest that the radio-frequency energy released by cell phones may increase the risk of two types of cancers: glioma, a type of brain cancer; and acoustic neuroma, a tumor of the nerve that runs from the ear to the brain.
Both types of cancers are rare: In the US, about 10,000 to 12,000 people develop a glioma each year and about 3,000 develop acoustic tumors. The elevated risk roughly doubles that risk after a decade of cell-phone use, according to some studies.
But the number of cell-phone users worldwide—about 5 billion—means a potential cancer link should be taken very seriously, said Dr. Jonathan Samet, chairman of the department of preventive medicine at the University of Southern California’s Keck School of Medicine and the chairman of the panel that issued the report.
“What we have here is a warning from a public health point of view,” Samet said. “We have half the world’s population already using cell phones, and people are using them younger and longer. We clearly need to keep track of this.”
Other scientists said they remained skeptical of the link, which is mired in contradictory science, and that they found the decision by the WHO perplexing.
“I find the conclusions surprising given that there is increasingly strong evidence that cell-phone use has no association with brain cancer occurrence,” said David A. Savitz, a professor in the departments of epidemiology and obstetrics and gynecology at Brown University and a researcher on environmental exposures and health. “With few exceptions, the studies directly addressing the issue indicate the lack of association.”
Cell phones were placed in a “possibly carcinogenic to humans” category by the International Agency for Research on Cancer, which develops scientific cancer-prevention strategies for the WHO. The agency’s other four categories for substances or agents are: carcinogenic to humans; probably carcinogenic to humans; not classifiable; and probably not carcinogenic to humans.
Scientists have long debated the potential cancer risk linked to cellphone use, but this statement marks the first time an independent group of scientists has taken anything other than a neutral stand.
“This is a major scientific consensus conference that has basically implicated cell-phone radiation with increased tumor risk, “ said Joel M. Moskowitz, director of the Center for Family and Community Health at the University of California, Berkeley’s School of Public Health and a long-time advocate of more research on the potential cell phone-cancer link. “I think they are particularly concerned about cell phones just because of the widespread utilization. It’s not like it’s some esoteric chemical used by industry that they think may be carcinogenic. Everyone is exposed to cell phones.”
The panel based its conclusions primarily on data from the multicountry Interphone studies that were coordinated by IARC, as well as research by Swedish cancer researcher Lennart Hardell. The Interphone data showed that people who used a cell phone 10 or more years had a doubled risk of glioma, a brain cancer that arises in the tissue surrounding and insulating brain cells.
One study showed a 40 percent increase risk of gliomas for people who used cell phone an average of 30 minutes a day over a 10-year period. About 10,000 cases of glioma are diagnosed each year in the United States.
A 2004 study put the increased risk of acoustic neuromas at twice the normal risk after 10 years of cellphone use and higher for tumors on the side of the head where the phone is typically placed.
There is too little evidence to draw conclusions about other types of cancer, the report stated, including a 2009 study by Israeli researchers that linked cell-phone use and cancer of the salivary gland.
But Savitz said the data are not compelling even for gliomas and acoustic neuromas. The more studies that are published on cell phones and health, he said, the more evidence accumulates that there is no increased cancer risk.
Many scientific questions remain, such as the lifetime risk of people who begin using wireless phones as children and just how cancer cells might arise from radio-frequency energy. But although the report will likely spur more calls for research, it’s not clear how much it will affect government policies, the cell-phone industry or consumers, experts said.
Groups representing the wireless industry downplayed the significance of the report, noting that the WHO placed radio-frequency electromagnetic fields in the “possibly carcinogenic” category, along with about 266 other agents, including gasoline and occupational exposure to dry cleaning.
(Los Angeles Times)
