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Question #: 253

Question: IT MORE DANGEROUS STAY FOR ONE HOUR AT A TEN-METER DISTANCE FROM CELLULAR ANTENNA OR TALK INTO PHONE THE SAME AMOUNT OF TIME?

Current Solution

Cellular phones are designed to be safe for both the user and anyone standing nearby. Cellular phones are actually small radios that transmit signals to and from base-station antennas located on towers or buildings in the nearby neighborhood. Cellular phones use low-power radio signals, even weaker than CB, police, or fire radios.

The American National Standards Institute (ANSI) sets safety standards for human exposure to radiofrequency (RF) electromagnetic energy in the United States. Government agencies such as the Federal Communications Commission (FCC), the Occupational Safety and Health Administration (OSHA), and many states recognize and accept the ANSI RF safety standard. Also, the United States standard for RF energy is comparable to those set in other countries.

Cellular phones and cellular-phone base stations have been shown to meet these RF safety standards. Safety standards for RF energy are threshold standards. Threshold standards define the level of RF energy above which there may be health or safety hazards and below which there have been no reported harmful effects. Unlike ionizing radiation, which many people believe to act cumulatively even at small exposure levels, RF energy at low levels is not considered a cumulative hazard. Therefore the consensus of scientific experts in this area is that RF exposure from cellular phones, meeting the threshold levels set in safety standards, is safe for all.

The specific answer to the question is that cellular phone technology is safe for all. There is no danger posed by either handheld phone units or by base-station antennas. In both cases, the radio signals transmitted from the antennas are required to meet the ANSI safety standard for RF safety as embodied in FCC regulations governing this technology. For more information:

The FCC has recently revised and reissued its Bulletin 56 on Questions and Answers about Biological Effects and Potential Hazards of Radiofrequency Electromagnetic Fields.

OSHA provides information and links to more sites on RF safety at its Web page, Radiofrequency/Microwave Radiation.

Gary Zeman, ScD, CHP Lawrence Berkeley National Laboratory

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Other Possible Solutions to this Question

  • HAVE THERE BEEN ANY STUDIES OF POSSIBLE RADIATION DANGER FROM HEADSETS USED WITH HANDSETS CORDED TELEPHONES? I A TELEPHONE BATTERY-POWERED HANDSET. THIS HANDSET HAS JACK FOR HEADSET, SO YOU CAN WALK AROUND THE HOUSE AND YARD ON YOUR BELT WHILE TALK INTO HEADSET. EITHER OR HEADSET GIVING OFF RADIATION, LIKE CELLULAR PHONE? DANGEROUS AMOUNT RADIATION?

    Headsets have been tested by the manufacturers and meet the current ANSI/IEEE standards for RF safety, the same standards that the Federal Communications Commission enforces under the Telecommunications Act of 1996. These standards place limits on the specific absorption rate (SAR) of radiofrequency (RF) energy in the body. Recent inflamatory articles in British press were not substantiated by testing in ISO-accredited testing facilities at Motorola. Manufacturers of cellular phones are required under FCC regulations to assure that their products meet the SAR limits on both hand-held and hands-free units. Further information may be available from the FDA or from the FCC. Ron Petersen, Lucent C.K. Chou, Motorola

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    HAVE THERE BEEN ANY STUDIES OF POSSIBLE RADIATION DANGER FROM HEADSETS USED WITH HANDSETS CORDED TELEPHONES? I A TELEPHONE BATTERY-POWERED HANDSET. THIS HANDSET HAS JACK FOR HEADSET, SO YOU CAN WALK AROUND THE HOUSE AND YARD ON YOUR BELT WHILE TALK INTO HEADSET. EITHER OR HEADSET GIVING OFF RADIATION, LIKE CELLULAR PHONE? DANGEROUS AMOUNT RADIATION?

  • THERE´S A CELLULAR PHONE ANTENNA ON THE ROOF OF BUILDING RIGHT OPPOSITE MY WINDOW, LEVEL ABOUT TEN METERS ABOVE HEAD. AM I LIKELY TO BE IN RADIUS RADIATION?

    You will have to contact the cell phone company that operates that particular antenna to obtain the radiation pattern (or emission pattern) of that particular type of antenna. Different models of antennae have different emission patterns to provide coverage of different size and shape geographical areas. For example, many of the antennae are directional, only broadcasting in the forward direction. Most emit very little radiation in the upward and downward directions, although the vertical extent of the beam can be quite different for different antennas. Some are strongly focussed on the horizon, others provide better coverage of nearby areas. Many antennae only broadcasting into a defined geometrical sector of the horizion, often 120 degrees so that three sets of antennae are required to cover the entire horizon. Therefore, to find the type of radiation pattern broadcast by any particular antenna will require local information from the equipment operator. Gary Zeman, ScD

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    THERE´S A CELLULAR PHONE ANTENNA ON THE ROOF OF BUILDING RIGHT OPPOSITE MY WINDOW, LEVEL ABOUT TEN METERS ABOVE HEAD. AM I LIKELY TO BE IN RADIUS RADIATION?

  • THERE ANY STANDARD FOR A DISTANCE BETWEEN CELLULAR BASE STATION AND RESIDENTIAL AREA?

    The two main constraints on siting cellular base stations near residential areas are government exposure limits and local zoning ordinances. Various governments have limits for human exposure to radiofrequency (RF) energy that must be complied with in the siting of cellular base stations and other transmitters. In the United States, the relevant limits are those of the Federal Communications Commission (FCC). Cellular base stations use low-powered transmitters, and RF signal levels are invariably below FCC limits at any distance more than a few feet from the antennas. Thus it is entirely feasible to locate cellular base stations on rooftops of apartment buildings and to locate communications towers within residential areas and indeed these are both common practices. Local zoning ordinances are a different story. Local governments commonly restrict the location of communications towers through zoning ordinances, and they may have provisions that restrict cellular base stations in residential districts. Local attorneys or government officials should be consulted for advice about local requirements, which vary greatly among jurisdictions. Kenneth R. Foster Professor, Department of Bioengineering University of Pennsylvania

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    THERE ANY STANDARD FOR A DISTANCE BETWEEN CELLULAR BASE STATION AND RESIDENTIAL AREA?

  • WHY IT DANGEROUS TO HAVE YOUR MOBILE PHONE IN OPERATION DURING REFUELING AT A GAS STATION?

    I can't think of any reason that it would be dangerous. However, I checked with the Cellular Telecommunications Industry Association. The Chairman of the Association sent the following memo on 18 June 1999, to the Associations' Board of Directors and others:
    "You may have received inquiries about wireless phones causing fires or explosions at gas stations. In particular, you may have been asked about an alleged explosion at a gas station in Indonesia. We have been unable to verify any such occurrence in Indonesia or anywhere else. Moreover, in our discussions with Shell Oil they have stated they have attempted to verify these reports and also have not been able to document any such occurrence."
    Nonetheless, in an abundance of caution, some manufacturers have included language in the owner's manuals for their products that recommends wireless phone users turn off their phones while at refueling points (gas stations). In addition, we have received information that Exxon will begin issuing warning signs at all domestic gas stations advising drivers to turn off all wireless communications devices when entering Exxon gas stations.

    While wireless phone owners should always consult their owner's manual for information on the use of the phone, we are not aware of any incident that would justify these concerns."

    Gen Roessler, Editor
    HPS website

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    WHY IT DANGEROUS TO HAVE YOUR MOBILE PHONE IN OPERATION DURING REFUELING AT A GAS STATION?

  • HOW MUCH RADIATION GIVEN OFF BY A CELL PHONE AND THERE ANY WAY TO STOP THE FROM BEING ABSORBED INTO YOURSELF?

    Portable cell phones emit about 0.6 watts of radiofrequency energy, limited primarily by the power of the battery. As with any radiofrequency transmitter, there will be some amount of absorption in the human body; the amount depends on how close you are to the antenna. The Federal Communications Commission (FCC) limits the amount of radiofrequency energy which cell phones can deposit in the body to levels at which no health effects are to be expected. See an article on Cell Phone Safety on this website for more information.

    Gary H. Zeman, ScD, CHP

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    HOW MUCH RADIATION GIVEN OFF BY A CELL PHONE AND THERE ANY WAY TO STOP THE FROM BEING ABSORBED INTO YOURSELF?

  • I'M SEARCHING FOR INFORMATION ABOUT THE HEALTH RISKS OF CELLULAR ANTENNAS' RADIATION. I NEED SCIENTIFIC (SCIENTIFIC PAPERS IN JOURNALS) THIS.

    Cellular telephone base stations are low-powered radiofrequency (RF) transmitters which operate at around 850-900 or 1800-1900 MHz (depending on the technology and region of the world). RF energy in a similar frequency range is used by many other technologies such as microwave ovens, UHF television, other communications systems, and radar. Health and safety issues related to RF energy have been studied for many years and there is an immense literature on the subject. Here are some sources that review health and safety issues related to RF energy from cellular base stations.

    A fact sheet published by the World Health Organization. There is also a Spanish version available on the WHO EMF website.
    Also see the IEEE EMBS Committee on Man and Radiation Report. Other reports are available through its website.
    The International Commission on Nonionizing Radiation Protection (ICNIRP) has published a lot on health and safety of RF energy. See its website. The ICNIRP published an article that describes the ICNIRP exposure limits for RF energy and their scientific rationale. See "Guidelines for Limiting Exposure to Time-Varying Electric, Magnetic, and Electromagnetic Fields (up to 300 GHz)," Health Physics Vol. 74, No 4, pp 494-522, 1998.
    A very detailed assessment of the scientific evidence related to health and safety of mobile telephones and base stations is in the recent (May 2000) report by the Independent Expert Group on Mobile Phones (IEGMP) titled "Mobile Phones and Health" This study concludes "the balance of evidence to date suggests that exposures to RF radiation at levels below [international exposure guidelines] do not cause adverse health effects to the general population" but that "there may be biological effects at exposures below those guidelines." Public exposure to RF energy from cellular base stations is invariably far below the ICNIRP exposure guidelines.

    Kenneth R. Foster
    Professor, Bioengineering
    University of Pennsylvania

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    I'M SEARCHING FOR INFORMATION ABOUT THE HEALTH RISKS OF CELLULAR ANTENNAS' RADIATION. I NEED SCIENTIFIC (SCIENTIFIC PAPERS IN JOURNALS) THIS.

  • ARE THERE PRODUCTS AVAILABLE TO THE GENERAL PUBLIC THAT CAN BE PURCHASED PROTECT CELLULAR OR PORTABLE TELEPHONE USERS FROM RADIATION? IF SO, WHERE THESE FOUND?

    There are a number of opportunistic gadgets on the market to allegedly protect the user from hazards of cellular phones. You can search the Internet to find the latest, ranging from antenna shields to whole-body shielding materials. Most experts believe that these devices take advantage of customers' misunderstanding and unfounded fears to sell products with no real value. First of all, cell phones that operate within the guidelines established by national and international safety panels have never been shown to pose a health risk to the user (see answers to other questions on cell phone safety on this website). Secondly, placing any kind of shield over the antenna of a cell phone will in most cases cause it to increase its RF output as it attempts to compensate for signal loss in the shield and maintain a quality phone call. The U.S. Food and Drug Administration published an advisory on cell phones several years ago that said if you are concerned about risks of using a cell phone, then simply use it less. That is still good advice today. Gary Zeman, ScD, CHP Lawrence Berkeley National Laboratory

    Additional Information:



    Additional Information:

    Click the link to add information to this solution:
    ARE THERE PRODUCTS AVAILABLE TO THE GENERAL PUBLIC THAT CAN BE PURCHASED PROTECT CELLULAR OR PORTABLE TELEPHONE USERS FROM RADIATION? IF SO, WHERE THESE FOUND?

  • IS IT DANGEROUS TO USE YOUR CELL PHONE AT A GAS STATION?

    I can't think of any reason that it would be dangerous. However, I checked with the Cellular Telecommunications Industry Association. The Chairman of the Association sent the following memo on 18 June 1999, to the Associations' Board of Directors and others:
    "You may have received inquiries about wireless phones causing fires or explosions at gas stations. In particular, you may have been asked about an alleged explosion at a gas station in Indonesia. We have been unable to verify any such occurrence in Indonesia or anywhere else. Moreover, in our discussions with Shell Oil they have stated they have attempted to verify these reports and also have not been able to document any such occurrence."
    Nonetheless, in an abundance of caution, some manufacturers have included language in the owner's manuals for their products that recommends wireless phone users turn off their phones while at refueling points (gas stations). In addition, we have received information that Exxon will begin issuing warning signs at all domestic gas stations advising drivers to turn off all wireless communications devices when entering Exxon gas stations.

    While wireless phone owners should always consult their owner's manual for information on the use of the phone, we are not aware of any incident that would justify these concerns."

    Gen Roessler, Editor
    HPS website

    Click the link to add information to this solution:
    IS IT DANGEROUS TO USE YOUR CELL PHONE AT A GAS STATION?

  • IT LIKELY THAT CELLULAR PHONE USAGE COULD EFFECT A CHANGE IN 400 MHZ NMR SPECTROMETER'S MAGNET IF HAS DECENT SHIELDING (TOP-OF-THE-LINE SHIELDING, CA. 1992)?

    Some electronic equipment has been shown to be sensitive to radiofrequency interference from cell phones. I suggest you talk with the manufacturer of the spectrometer for information about it.

    Gary H. Zeman, ScD, CHP

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    IT LIKELY THAT CELLULAR PHONE USAGE COULD EFFECT A CHANGE IN 400 MHZ NMR SPECTROMETER'S MAGNET IF HAS DECENT SHIELDING (TOP-OF-THE-LINE SHIELDING, CA. 1992)?

  • my motors start clicking/stepping one step at a time and if I run a toolpath, the motors run runan inch or so them stop and make a lot of noise. Scretching almost. Any ideas.

    If your motors are making a strange noise as it begins a motion, or as it ramps up to the desired speed, then it is hitting it's maximum torque. First, make sure that your motor tuning (steps/inch, velocity and acceleration) are set correctly. The steps per inch should be set according to the microstepping set on the driver, and for the specific mechanics that is being used on that axis. Step/inch = (200 * microstepping) / (number of inches for one complete revolution). Second, make sure the correct current and microstepping is set on the driver for the motor that is having issues.

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    my motors start clicking/stepping one step at a time and if I run a toolpath, the motors run runan inch or so them stop and make a lot of noise. Scretching almost. Any ideas.

  • Are there plans to release a USB Controller to work with the Planet CNC Output Board for more advanced spindle control from within Planet CNC?

    At this time we are working to release a new USB controller board that will be compatible with Mach4 software and do not have any immediate plans to update the Planet-CNC USB board.

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    Are there plans to release a USB Controller to work with the Planet CNC Output Board for more advanced spindle control from within Planet CNC?

  • DOES THE RADIATION ONLY EXIST WHEN I'M ACTUALLY MAKING A CALL, OR JUST ANY TIME PHONE ON?

    Whenever they are turned on, cell phones communicate at infrequent intervals with a nearby base station even when they are not being used for a call. This is necessary to tell the system where the user is in case a call should come in. Thus, even while they are inactive, the phones are a source of (very low) radiofrequency energy exposure to the user. Hands-free kits reduce exposure to a user by removing the phone from the vicinity of the head. There is no identifiable health benefit in using the kits, but there is no detriment either, and using them may increase a user's peace of mind. Contrary to a widely publicized report by a British magazine last year, the kits are effective in reducing exposure. (This is not necessarily true of other devices that can be bought to be used with phones.) In your case, the cell phone and hands-free kit are clearly an important link to the outside world and I would not hesitate in using them. There may be comfort issues with having the earpiece in place for a long time, but radiofrequency radiation exposure should not be a concern at all. The hands-free kits will reduce exposure below that which you would receive if the phone were kept close to your head. Kenneth R. Foster Professor, Department of Bioengineering

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    DOES THE RADIATION ONLY EXIST WHEN I'M ACTUALLY MAKING A CALL, OR JUST ANY TIME PHONE ON?

  • I WOULD LIKE TO INQUIRE ABOUT THE PHYSICS PRINCIPLES REGARDING USE OF MOBILE PHONES AND DEVELOPMENT BRAIN TUMORS. I'VE BEEN THROUGH MANY SITES BUT THEY CAN NEVER GIVE AN EXACT ANSWER. REALLY SOMEONE TUMORS OR DOES IT HAVE DO WITH INTENSITY RADIATION DISTANCE BETWEEN PHONE INDIVIDUAL?

    It is not clear that mobile phones do produce brain tumors, or any serious health effects for that matter. A number of epidemiology studies have been almost completely negative on the issue.

    See the article I wrote with John Moulder in IEEE Spectrum magazine and also Moulder's FAQ on mobile phones and health.

    There has been a lot of discussion over the years about the possible mechanisms by which microwave energy such as emitted by cell phones might produce biological effects. The one unequivocal mechanism is the heating of tissue, but mobile phones operate at power levels that are too low to cause noticeable heating in the user. Scientists have speculated about other mechanisms, but these theories remain unproven and many of them have been challenged on biophysical grounds.

    Whatever may be the risks or nonrisks of mobile phone radiation, a hands-free kit is an effective way for the user to reduce his or her exposure to radiofrequency energy while using a mobile phone.

    Kenneth R. Foster, Professor
    Department of Bioengineering
    University of Pennsylvania

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    I WOULD LIKE TO INQUIRE ABOUT THE PHYSICS PRINCIPLES REGARDING USE OF MOBILE PHONES AND DEVELOPMENT BRAIN TUMORS. I'VE BEEN THROUGH MANY SITES BUT THEY CAN NEVER GIVE AN EXACT ANSWER. REALLY SOMEONE TUMORS OR DOES IT HAVE DO WITH INTENSITY RADIATION DISTANCE BETWEEN PHONE INDIVIDUAL?

  • WHAT EFFECTS OF CELL PHONES WILL THERE BE ON YOUNGER PEOPLE OPPOSED TO OLDER PEOPLE? THE AGE OR STATE DEVELOPMENT EFFECT DANGERS A PHONE?

    Physical size of the subject affects the fraction of the total radiofrequency energy that is absorbed in the body. To account for this known effect, the maximum permissible exposure standards for radiofrequency energy were set for the worst-case condition, that is assuming the body size for maximal absorption at a given frequency. Thus the maximum permissible exposure standards are fully protective for bodies of different sizes. For more detailed information, see the answers and the cited references to questions 79, 109, 694, and 893 under the Nonionizing Radiation section of the Health Physics Society Ask The Expert Web page. Gary H. Zeman, ScD, CHP

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    WHAT EFFECTS OF CELL PHONES WILL THERE BE ON YOUNGER PEOPLE OPPOSED TO OLDER PEOPLE? THE AGE OR STATE DEVELOPMENT EFFECT DANGERS A PHONE?

  • Can we use a more powerful laser tube in the blackTooth? Say, 100w from ColeTech? Are they just physically too large/long?

    If the laser tube is the same dimensions then yes, that tube can be implemented and take into account the required laser power supply and safety protocols on that high powered laser tube.

    Our blackTooth is a fixed machine and is only made for the 40 watt laser tube that we sell.

    Click the link to add information to this solution:
    Can we use a more powerful laser tube in the blackTooth? Say, 100w from ColeTech? Are they just physically too large/long?

  • The motor was tested on the same axes were the others work but one of the NEMA 24 425 Oz motors dose not turn just jitters.

    The NEMA 25 motor uses a different current than other motors. Make sure when you test the NEMA 25 motor, the current setting is at 2.43.

    Click the link to add information to this solution:
    The motor was tested on the same axes were the others work but one of the NEMA 24 425 Oz motors dose not turn just jitters.

  • Regards   I hope to know the time it takes for shipping by USPS Priority mail international to Jeddah in Saudi Arabia Thank you

    The usual travel time overseas, takes around 1 week to 3 weeks depending on the carrier and service selected.

    Click the link to add information to this solution:
    Regards   I hope to know the time it takes for shipping by USPS Priority mail international to Jeddah in Saudi Arabia Thank you

  • Regards   I hope to know the time it takes for shipping by USPS Priority mail international to Jeddah in Saudi Arabia Thank you

    The usual travel time overseas, takes around 1 week to 3 weeks depending on the carrier and service selected.

    Click the link to add information to this solution:
    Regards   I hope to know the time it takes for shipping by USPS Priority mail international to Jeddah in Saudi Arabia Thank you

  • Regards   I hope to know the time it takes for shipping by USPS Priority mail international to Jeddah in Saudi Arabia Thank you

    The usual travel time overseas, takes around 1 week to 3 weeks depending on the carrier and service selected.

    Click the link to add information to this solution:
    Regards   I hope to know the time it takes for shipping by USPS Priority mail international to Jeddah in Saudi Arabia Thank you

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