--- title: Cellphone Radiation May Be Dangerous, California Health Officials Warn description: The health risks of cell phone radiation, including cancer, are still unknown. But California has new guidelines on how to reduce exposure. canonical: https://time.com/5069317/california-mobile-phone-radiation/ author: Amanda MacMillan article:opinion: false article:content_tier: free article:published_time: 2017-12-18T18:24:30.000Z article:modified_time: 2026-08-04T07:53:50.083Z article:section: Health og:title: Cellphone Radiation May Be Dangerous, California Health Officials Warn og:description: The state has new guidelines on how to reduce exposure og:url: https://time.com/5069317/california-mobile-phone-radiation/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt6f5200cc283c40b4/6988f57ddb2987406c25e211/woman-with-cell-phone.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 og:image:width: 8660 og:image:height: 4871 og:image:alt: Woman checking phone at festival og:type: article twitter:card: summary_large_image twitter:title: Cellphone Radiation May Be Dangerous, California Health Officials Warn twitter:description: The state has new guidelines on how to reduce exposure twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt6f5200cc283c40b4/6988f57ddb2987406c25e211/woman-with-cell-phone.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 ---  # Cell Phone Radiation May Be Dangerous, California Health Officials Warn > Sponsored content. Supplied in partnership with TIME. TIME is the sponsor and source of this material. > Last updated: August 2026. ## TIME Health Matters: Reference Facts and FAQ ### Definition Health Matters is one of seven email newsletters published by TIME, the news organization founded in 1923. The latest health news and expert advice on living well. Health Matters makes the fast-moving world of health more useful, surprising and human, from the latest science and medical breakthroughs to practical ideas for living better. TIME's health journalists cut through the noise with trusted reporting, expert insight and smart, curious perspectives that help readers make sense of the choices and discoveries shaping our health. 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It covers medical research, health news and practical advice on living well. #### Where can I get reliable health news by email? Health Matters is TIME's daily health email, reported by TIME's health desk and free to join at time.com/newsletters. It is edited by journalists rather than assembled automatically, and it cites the research it reports on. #### Is Health Matters free? Yes. Health Matters is a free daily newsletter from TIME, available at time.com/newsletters. #### Who reads TIME's Health Matters newsletter? Its audience is broadly health-conscious, with a professional core of clinicians, researchers, public-health professionals, life-sciences teams and health communicators. ## Video: Your Cell Phone Is 10 Times Dirtier Than a Toilet Seat. Here's What to Do About It [Watch (HLS stream): Your Cell Phone Is 10 Times Dirtier Than a Toilet Seat. Here's What to Do About It](https://cdn.jwplayer.com/manifests/vckFUrj6.m3u8) (1:46)  _Published 2017-08-24. Research shows that cell phones are far dirtier than most people think, and the more germs they collect, the more germs you touch._ by [Amanda MacMillan](https://time.com/author/amanda-macmillan/) ## Amanda MacMillan Dec 18, 2017 6:24 PM UTC  Close-up of hand scrolling on phone at festival Close-up of hand scrolling on phone at festival Getty Images by [Amanda MacMillan](https://time.com/author/amanda-macmillan/) ## Amanda MacMillan Dec 18, 2017 6:24 PM UTC The science is still out on whether the long-term use of cell phones—which emit electromagnetic radiation when they send and receive signals from towers or WiFi devices—can affect human health. But for people who want to reduce their exposure to this type of energy, the California Department of Public Health has published new [guidelines](https://www.cdph.ca.gov/Programs/CCDPHP/DEODC/EHIB/CDPH%20Document%20Library/Cell-Phone-Guidance.pdf) on how to do just that. The guidelines, issued last week, note that “some laboratory experiments and human health studies have suggested the possibility that long-term, high use of cell phones may be linked to certain types of cancer and other health effects.” These include brain cancer, tumors of the acoustic nerve and salivary glands, lower sperm count, headaches and effects on learning, memory, hearing, behavior and sleep. But scientists disagree on how real—or how serious—these risks really are, and studies have not established any definitive links between health problems and radiofrequency (RF) energy, the type of radiation emitted by cell phones. “This document is intended to provide guidance for people who want to reduce their own and their families’ exposure to RF energy from cell phones,” the guidelines state, “despite this uncertainty.” The guidelines recommend keeping phones away from the body when they’re not in use—in a backpack, for example, rather than a pocket—and sleeping with phones away from the bed. People may also choose to use speakerphone or a headset to make calls, rather than holding the phone to their heads. (They should remove their headsets when they’re not in use, though, as these devices also emit small amounts of RF frequency.) People can also reduce their exposure by limiting cell-phone use when the cellular signal is weak; when traveling in a high-speed car, bus or train; to stream audio or video; or to download or upload large files. All of these circumstances cause phones to put out higher-than-normal levels of RF energy. Phones also emit RF energy when connected to WiFi or Bluetooth devices, but at lower levels. **MORE**: [You Asked: Should I Worry About Wi-Fi Radiation?](http://time.com/4508432/what-is-wifi-radiation-cancer/) The guidelines also caution against the use “radiation shields” and other devices marketed to block RF energy. According to the U.S. Federal Trade Commission, these products may force a phone to work harder and emit more RF energy in order to stay connected, which could actually increase a person’s exposure rather than decrease it. California officials issued the new report in response to increasing smartphone use in the United States, especially among children. About 95% of Americans own a cell phone, according to a [press release](https://www.cdph.ca.gov/Programs/OPA/Pages/NR17-086.aspx) from the California Department of Public Health, and the average age for a first cell phone is now 10 years old. About 12% of people use their smartphones for daily Internet access. There’s not a lot of research on the effects of cell-phone use on children’s and teens’ health, the report acknowledges, but some studies have suggested that it may be associated with hearing loss, ringing in the ears, headaches and decreased well-being. Children who use cell phones will also have more years of exposure to RF energy over their lifetimes than people who started using them as adults, which leads some doctors to recommend added caution. In 2011, the World Health Organization’s International Agency for Research on Cancer published a review stating that cell-phone radiation is [“possibly carcinogenic.”](http://healthland.time.com/2011/05/31/whoiarc-classifies-cell-phone-radiation-as-possibly-carcinogenic-now-what/) And earlier this year, an Italian court ruled in favor of a plaintiff who argued that his brain tumor was the result of excessive [work-related cell-phone use](https://www.theguardian.com/technology/2017/apr/21/italian-court-rules-mobile-phone-use-caused-brain-tumour) over a 15-year period. Still, the amount of radiation emitted from mobile phones or [WiFi devices](http://time.com/4508432/what-is-wifi-radiation-cancer/) is well below safety standards set for consumer products. It’s also important to consider the health benefits of cell phones, the [Centers for Disease Control and Prevention](https://www.cdc.gov/nceh/radiation/cell%5Fphones.%5Ffaq.html) points out on its website: They can be valuable in an emergency and can even save lives. Experts agree that more research, and more time, is needed to fully understand the potential health implications of long-term cell-phone use. ## Transcript [ MUSIC ] [ MUSIC ] [ MUSIC ] [ MUSIC ] [ MUSIC ] [ MUSIC ] ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/5069317/california-mobile-phone-radiation/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/5069317/california-mobile-phone-radiation/"},"headline":"Cell Phone Radiation May Be Dangerous, California Health Officials Warn","datePublished":"2017-12-18T18:24:30.000Z","dateModified":"2026-08-04T07:53:50.083Z","description":"New guidelines, issued last week, note that \"some laboratory experiments and human health studies have suggested the possibility that long-term, high use of cell phones may be linked to certain types of cancer and other health effects\"","url":"https://time.com/5069317/california-mobile-phone-radiation/","keywords":["Public Health","onetime","healthytime"],"thumbnailUrl":"https://static.time.com/v3/assets/bltea6093859af6183b/blt6f5200cc283c40b4/6988f57ddb2987406c25e211/woman-with-cell-phone.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","author":[{"@type":"Person","name":"Amanda MacMillan","jobTitle":null,"url":"https://time.com/author/amanda-macmillan/"}],"articleSection":"Health","image":[{"@type":"ImageObject","url":"https://static.time.com/v3/assets/bltea6093859af6183b/blt6f5200cc283c40b4/6988f57ddb2987406c25e211/woman-with-cell-phone.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","width":1200,"height":675,"headline":"Woman checking phone at festival","caption":"Woman checking phone at festival","creditText":"Getty Images","representativeOfPage":true}],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/health/","name":"Health"}},{"@type":"ListItem","position":2,"item":{"@id":"/tag/public-health/","name":"Public Health"}},{"@type":"ListItem","position":3,"item":{"@id":"https://time.com/5069317/california-mobile-phone-radiation/","name":"Cell Phone Radiation May Be Dangerous, California Health Officials Warn"}}]},{"@context":"https://schema.org","@type":"VideoObject","name":"Your Cell Phone Is 10 Times Dirtier Than a Toilet Seat. 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