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Question #: 256

Question: ARE CELLULAR PHONE HARMFUL?

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

  • ARE CELLPHONES HARMFUL?

    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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    ARE CELLPHONES HARMFUL?

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

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

  • WILL IT BE HARMFUL TO USE MY MOBILE PHONE DURING PREGNANCY? IF HARMFUL, SHOULD I DISCONTINUE USING OR MODERATELY?

    Thank you for your inquiry about the risk to your embryo by using a cellular phone during pregnancy. Sometimes it is not made clear to the public that there are different kinds of radiation. The electrical fields from a cellular phone are nothing like x ray. The energy is so low in the electrical waves of cellular phones that it does not represent a risk to the developing embryo. If you use the cellular phone conventionally by placing it to your ear, you further reduce the exposure to the embryo, which is already extremely low because of the distance of the phone from your ear to your uterus. There are no studies dealing with the risks of cellular phones on the outcome of pregnancy in humans, but numerous animal studies indicate that the exposures from the phones do not represent a risk for birth defects or miscarriage. Of course you must realize that every healthy pregnant woman begins her pregnancy with a 3% risk for birth defects and a 15% risk for miscarriage. Good luck with your pregnancy.

    Robert Brent MD, PhD, DSc(Hon)

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    WILL IT BE HARMFUL TO USE MY MOBILE PHONE DURING PREGNANCY? IF HARMFUL, SHOULD I DISCONTINUE USING OR MODERATELY?

  • ARE LIVING QUARTERS IMMEDIATELY BELOW ROOF-TOP CELLULAR TELEPHONE ANTENNA/TRANSMITTERS HAZARDOUS?

    There is very little radiofrequency (RF) energy exposure to people inside a building from a cellular base station located on its roof. There are several reasons for this. First, the transmitters operate at low power levels. Second, the antennas are normally mounted near the edges of the roof and are aimed away from the building. Third, most cellular transmitters use "high gain" or panel antennas. Such antennas transmit most of their energy in a narrow beam (in the vertical direction) from their front surfaces, away from the building. They radiate very little energy downwards towards the roof or backwards from their rear surfaces. Finally, building materials absorb a significant fraction of the RF energy passing through them. As a result, the RF signal levels at any location inside the building are invariably low and far below safety limits. The situation might be different in some locations on the roof itself. RF signal levels close to (within a few feet) and directly in front of cellular base station antennas can easily exceed safety limits. Some precautions are needed to prevent people from walking directly in front of the antennas while they are transmitting. This applies also to paging and other systems that use rooftop antennas, some of which transmit at higher power levels than many cellular base stations. Kenneth R. Foster, Ph.D.

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    ARE LIVING QUARTERS IMMEDIATELY BELOW ROOF-TOP CELLULAR TELEPHONE ANTENNA/TRANSMITTERS HAZARDOUS?

  • WHAT ARE THE HEALTH RISKS OF LIVING NEAR A CELL PHONE TOWER?

    There is very little radiofrequency (RF) energy exposure to people inside a building from a cellular base station located on its roof. There are several reasons for this. First, the transmitters operate at low power levels. Second, the antennas are normally mounted near the edges of the roof and are aimed away from the building. Third, most cellular transmitters use "high gain" or panel antennas. Such antennas transmit most of their energy in a narrow beam (in the vertical direction) from their front surfaces, away from the building. They radiate very little energy downwards towards the roof or backwards from their rear surfaces. Finally, building materials absorb a significant fraction of the RF energy passing through them. As a result, the RF signal levels at any location inside the building are invariably low and far below safety limits. The situation might be different in some locations on the roof itself. RF signal levels close to (within a few feet) and directly in front of cellular base station antennas can easily exceed safety limits. Some precautions are needed to prevent people from walking directly in front of the antennas while they are transmitting. This applies also to paging and other systems that use rooftop antennas, some of which transmit at higher power levels than many cellular base stations. Kenneth R. Foster, Ph.D.

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    WHAT ARE THE HEALTH RISKS OF LIVING NEAR A CELL PHONE TOWER?

  • 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?

  • 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)?

  • 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?

  • CELL PHONE USE

    Hands-free cell phone car microphones have been tested by the manufacturers and meet the current ANSI/IEEE (American National Standards Institute/Institute of Electrical and Electronics Engineers) standards for radiofrequency (RF) safety. These are the same standards that the Federal Communications Commission enforces under the Telecommunications Act of 1996, and they place limits on the specific absorption rate (SAR) of RF energy in the body. Recent inflammatory articles in the British press were not substantiated by testing at ISO-accredited testing facilities at Motorola. Manufacturers of cell 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 can be obtained on the Internet at The Center for Devices and Radiological Health (FDA information) or Office of Engineering and Technology (FCC information).

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    CELL PHONE USE

  • 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

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

  • 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

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    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?

  • THE MOTORS ARE NOT TURNING

    Make sure you follow the tutorial here: http://www.buildyourcnc.com/CNCElectronicsandWiring.aspx

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    THE MOTORS ARE NOT TURNING

  • MY MOTORS ARE RUNNING VERY HOT.

    If your motors are hot to the touch, this is normal. Current is being drawn by the motor coils as the motor moves and as the motor stays at a position. If the motor is not using the current in the coils to move (holding it's position), the energy will be translated as heat (rather than motion, sound or light). Even while moving, some of the energy will be lost as heat. Remember that energy cannot be created nor destroyed.

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    MY MOTORS ARE RUNNING VERY HOT.

  • WHAT ARE CHINA PRICES FOR COLLETS?

    From: Milan Shah
    ACCU-FIX Precision Tools Pvt Ltd
    458, Manjusar GIDC, Savli, Vadodara, Gujarat, India
    Mobile: +(91) 7567975718

    ER 11 - STD. Precision Collet $3.61 - No 1/2" shank sizes.
    ER 16 - STD. Precision Collet $4.05
    ER 20 - STD. Precision Collet $4.27
    ER 25 - STD. Precision Collet $4.34
    ER 32 - STD. Precision Collet $4.69
    ER 40 - STD. Precision Collet $5.32
    ---------------------------------------------------------------

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    WHAT ARE CHINA PRICES FOR COLLETS?

  • MY PARTS ARE COMING OUT THE WRONG SIZE

    In Mach3, go to the Settings Tab, and select "Set Steps Per Unit". It will ask you how far to move the machine. Before you do this, make a mark on the table exactly where the end mill is resting. You can do this by lowering the end mill until it touches the material, then spinning it by hand to cut a small dimple in the material. Then, raise the end mill to clear the material, and assign a distance to move the machine. Once the machine moves and stops, measure the exact distance that it actually traveled with a tape measure, and enter this value into the dialog box that asks how far it moved. Mach3 will automatically adjust your steps per unit for that axis to be more accurate. Do this for all axes often to ensure you are cutting accurately. The longer distances you use calibrate, and the more precise you are with your measurements, the better.

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    -1' OR 2+886-886-1=0+0+0+1 --

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    -1' OR 2+357-357-1=0+0+0+1 or 'xkLzGxAb'='

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    -1" OR 2+279-279-1=0+0+0+1 --

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    MY PARTS ARE COMING OUT THE WRONG SIZE

  • WHAT ARE THE CABLE LENGTHS FOR BLACKTOE

    The motor cables for the blackToe are as follows:

    Total 30 feet

    X - 9
    Y - 10
    Z - 11

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    WHAT ARE THE CABLE LENGTHS FOR BLACKTOE

  • WHAT ARE THE CABLE LENGTHS FOR BLACKTOE

    The motor cables for the blackToe are as follows:

    Total 30 feet

    X - 9
    Y - 10
    Z - 11

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    WHAT ARE THE CABLE LENGTHS FOR BLACKTOE

  • WHERE ARE THE ELECTRONICS WIRING VIDEOS?

    The blackFoot CNC machine kit does not include a table. The table can be made as long or shot as you need. for instance, if you are looking for a travel of 4 fet x 4 feet, then the table will need to be about 6 feet long to get the full 4 feet of travel.

    The electronics are very straight forward using the connection diagram for the breakout board that you select. Use the videos for a general idea and then use the connection diagram to verify the correct connections for the interface of your choosing.

    Yes,the USB interface replaces the breakout board, but remember that you will need to use the planet-cnc software with the USB interface.

    Additional Information:
    The electronics does accompany the cnc machine kits as long as you select the option "with electronics". There are option to purchase the machines without electronics and that would be necessary if you either have your own electronics, or you prefer the plug and play cnc computer system we call the redLeaf, or redSprout. This will also be necessary if you prefer the electronics that use the USB interface rather than the parallel interface.

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    WHERE ARE THE ELECTRONICS WIRING VIDEOS?

  • WHERE ARE THE ELECTRONICS WIRING VIDEOS?

    The electronics and wiring videos are located under the tutorials section (click Tutorials on the top menu. The Title is "CNC Electronics and Wiring". The actual link to these videos is: https://www.buildyourcnc.com/CNCElectronicsandWiring.aspx

    Additional Information:
    You will also find the electronic wiring videos for the USB controller at: https://www.buildyourcnc.com/tutorials/tutorial-Electronics-USB-Interface-Wiring

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    WHERE ARE THE ELECTRONICS WIRING VIDEOS?

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