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Cell Phone Safety Standards

 

Cell Phone Radiation Science Review

Section 2: Cell Phone Safety Standards

Radiofrequency radiation associated with cell phones

FCC established the first radiation standards for cell phones in 1996, 13 years after cell phones were first marketed in the U.S. The agency adopted limits recommended by industry (IEEE C95.1-1991) that were established to protect against high-dose thermal effects, that allow a 20-fold higher exposure to the head (1.6 W/kg) compared to the rest of the body (0.08 W/kg), and that do not account for a child’s higher exposure and greater vulnerability to cell phone radiation.

In the U.S., cell phones operate at electromagnetic wave frequency of either 800-900 megahertz (MHz) or 1800-1900 MHz. This frequency range is called radiofrequency (RF), since radios and TVs operate in the same portion of electromagnetic spectrum. The power density or intensity of transmitted electromagnetic field (EMF) is measured in watts (W) per m2 or, more commonly, milliwatts per cm2 (mW/cm2).

Cell phone radiation is transmitted by the antenna and the circuit elements inside the handset. The antenna and the circuit elements send out the electromagnetic wave (RF radiation) to transmit the signal. The inner antenna is usually a metal helix or a metal rod a few centimeters long that is able to transmit RF radiation of sufficient power so as to deliver the signal from the handset to the base station. The antenna is typically located on the back of a cell phone or a wireless device. The power at which a cell phone must transmit to reach a base terrestrial station is affected by many factors, such as frequency (900 or 1800 MHz), the phone distance from the base station, and physical obstacles between the phone and the base station. To overcome obstacles and interference, a cell phone transmits at greater power. This power is controlled from the base station.

In a rural area with sparse locations of cell phone towers, cell phones need to transmit signal at a greater power (Hillert 2006). A study in Sweden demonstrated that in the rural area, the highest power level was used about 50% of the time, while the lowest power was used only 3% of the time. The corresponding numbers for the city area were approximately 25% and 22% (Lonn, Forssen 2004). In agreement with these data, rural users of cell phones appear to be at a higher tumor risk compared to urban users, likely due to higher power radiation emitted by a phone when located further away from a base station (Hardell 2005; Sadetzki 2008).

EMF radiation emitted by a cell phone antenna is not very directional – similar amounts of radiation are transmitted outward, towards the base station, and inward, towards the ear/head of a cell phone user where they readily penetrate into the body and are absorbed into the inner tissues (Independent Expert Group on Mobile Phones (IEGMP) 2000). Of note, it is possible to design directional antennas so as to decrease radiation exposure to the cell phone user (Wireless Galaxy 2009). Multiple factors influence how much radiation goes into the head, including: the type of digital signal coding in the network, such as GSM (Global System for Mobile Communication), CDMA (Code division multiple access) or UMTS (Universal Mobile Telecommunication System); the antenna design; location of the antenna relative to the head; and the position of the hand or use or an earpiece (Swiss Federal Office of Public Health 2009c).

Of the total radiation emitted towards the head, most (97–99%, depending on frequency and cell phone network) is absorbed in the brain hemisphere on the side where the phone is used (Cardis 2008). The temporal lobe, an area of the brain involved in auditory processing, formation of long-term memory, as well as some aspects of speech and vision, receives the highest radiation exposure (Cardis 2008). Additionally, when a phone is worn near the waist during its use (as may occur when a corded or a cordless headset is used), much of the outgoing radiation is be absorbed by adjacent soft tissues, which may pose health risks (Agarwal 2009; Swiss Federal Office of Public Health 2009c; Whittow 2008).

Absorption of radiofrequency energy involves interaction with polar molecules or ions inside the cells and in extracellular fluids such as cerebrospinal fluid, leading to readily detectable temperature elevation in organs and tissues (ICNIRP 1998; IEEE 2006). The heat generated in tissues absorbing RF energy can cause thermal effects that range from behavioral problems to damage to sensitive tissues like the eyeball or testicle. Researchers have also suggested non-thermal mechanisms of action for some of the effects seen in studies, including effects on ion channels within a cell, effects on membrane enzymes, creation of membrane pores, and free radical formation; scientists worldwide are actively investigating these possible effects of cell phone radiation (NRC 2008b; Weaver 2006).

Specific absorption rate (SAR) for the cell phone radiation

Biological effects caused by radiofrequency radiation depend on the rate at which the energy is absorbed by a particular mass of tissue, calculated as specific absorption rate, or SAR, and measured in watts per kilogram (W/kg). Since brain structures on the side where a cell phone is used (the ipsilateral side) receive significantly higher dose of radiation, and since radiation is unevenly absorbed into different types of tissues (bone, cartilage, nervous tissue, or distinct anatomical structures within the brain), international experts agree that more precise SAR measurements can be obtained when averaging over a smaller volume of tissue (Cardis 2008).

In general, energy absorption rate increases with greater conductivity of tissue and decreases with greater tissue density. Absorption rate is also directly proportional to the intensity of the electromagnetic field (its power density). To carry out an SAR test, a mold in the shape of human torso or head is filled with a fluid designed to simulate the electrical properties of human tissue. Typically, a head model is filled with a thick, viscous mixture that is meant to simulate the conductivity of head tissues; the mixture includes water, salt, sugar, and a chemical viscosity additive. During testing the phone is placed next to the outer surface of the mold and made to transmit a signal at full power while an inner probe is moved through the fluid mixture, measuring the radiofrequency energy that is being absorbed at various locations (IEC 2005). The certified SAR level of a given phone is supposed to be the highest SAR value measured during those tests.

FCC, the industry, and the academic community all acknowledge that SAR measurements have significant precision problems (Cardis 2008; Conil 2008; FCC OET 2008e; GAO 2001; Wiart 2008). Studies by scientists in academia and the cell phone industry, demonstrated that it is difficult to generalize between the SAR induced in two given heads, for people of different ages or body types (Wiart 2008). Although significant methodological improvements occurred over the last decade, in 2008 FCC reported persisting “issues and concerns in applying these [SAR] procedures correctly” (FCC OET 2008b). Additionally, two modeling studies carried out in Japan demonstrated that the whole body SAR can be substantially higher than the current standard when short subjects are exposed to high-power cell phone radiation (Hirata 2007; Wang 2006).

The current SAR standard may pose especial risk to the health of children (Martinez-Burdalo 2004). Children’s tissues have higher numbers of ions compared to adults, resulting in greater conductivity and increased capacity to absorb radiation (Gabriel 2005; Peyman 2009). Children’s heads also have smaller thicknesses of the pinna, skin and skull, reducing the distance from the handset to the peripheral brain tissues (Conil 2008; Wiart 2008). These factors result in higher SAR exposure for young children. According to a recent study with SAR testing models designed to correspond to the 5-8 year old child, a child’s head would absorb twice the radiation of an adults’ (Wiart 2008). Similar results have been reported by the University of Utah researchers in 1996 (Gandhi 1996) and by the researchers from the Nagoya Institute of Technology (Japan) in 2003 (Wang 2003). Due to higher absorption of radiation, when a child uses a high-emitting cell phone, he or she could easily get an exposure over the current FCC limit (Conil 2008).

U.S. SAR standards for cell phones

The FCC limits for cell phone radiation exposure (47CFR 2.1093(d)), based on IEEE recommendations, permit the following SAR levels for whole-body exposure and for partial-body or localized exposure (FCC 1997, 1999):

  • Partial-body exposure (head): up to 1.6 W/kg, averaged over 1 g of tissue;
  • Whole-body exposure: up to 0.08 W/kg, averaged over 1 g of tissue;
  • Hands, wrists, feet, and ankles: up to 4 W/kg, averaged over 10 grams of tissue.

The current SAR standards for radiofrequency radiation were based on animal studies conducted in the late 1970s and early 1980s. These studies demonstrated behavioral alterations, such as disruption of food-motivated learned behavior, in several animal species, including non-human primates (squirrel monkeys) at an SAR above 4 W/kg (IEEE 2006; Osepchuk 2003). According to the Institute of Electrical and Electronics Engineers (IEEE) International Committee on Electromagnetic Safety, these behavioral changes “may be a potentially adverse effect in human beings” (IEEE 2006).

FCC, on the recommendation of the IEEE, adopted an SAR level of 4 W/kg as the point of departure for determining legal SAR limits for cell phones. In contrast to the FCC position, an independent analysis by the EPA scientists concluded, on the basis of the same body of data, that biological effects occur at SAR levels of 1 W/kg, 4 times lower than the level chosen by IEEE (U.S. EPA 1984). The EPA’s Science Advisory Board reviewed the draft EPA report twice prior to publication. The Science Advisory Board concluded that the report “represents an adequate statement of the current scientific literature and can serve as a scientifically defensible basis for the Agency’s development of radiation protection guidance for use by Federal agencies to limit exposure of the general public to radiofrequency radiation” (SAB 1984).

Based on the EPA analysis, a point of departure at 1 W/kg SAR may well be a more scientifically defensible hazard level that should be used for determining legally acceptable exposure limits. In fact, the EPA scientist in charge of editing the 1984 report, D.F. Cahill, published a peer-reviewed paper where he indicated that SAR of 0.4 W/kg is likely to be a conservative threshold point (Cahill 1983), 10 times lower than the departure point chosen by IEEE. This conclusion is supported by a growing body of studies from researchers world-wide that observe biological effects of cell phone radiation at SAR values significantly below the limits adopted by FCC (reviewed in (BioInitiative 2007; Independent Expert Group on Mobile Phones (IEGMP) 2000)).

Of note, the IEEE-recommended SAR of 4 W/kg as the point of departure for adverse health effects corresponds to short-term exposure and does not take into account long-term or chronic exposure (RFIAWG 1999). Thus, the existing FCC cell phone standard may well be insufficient for protecting human health from potential effects of life-long use, especially for susceptible populations such as young children.

Slim margin of safety provided by the current FCC standards

The FCC standards, adopted from the 1992 IEEE recommendation, are not based on a comprehensive risk assessment and fail to provide a reasonable margin of safety for exposure to cell phone radiation. Assuming a conservative, and likely overestimated departure point for health effects at an SAR value of 4 W/kg, the exposure standard for the head, at 1.6 W/kg, has only a 2.5-fold margin from the level that produced adverse behavioral effects in laboratory animals, even though it is possibly the most sensitive part of the human body. Most government health standards for environmental exposures include a safety margin of at least 100 to account for differences between lab animals and humans and for the vulnerability of children and other sensitive subpopulations.

Exposure to hands, wrists, feet, and ankles at 4 W/kg, has no safety margin whatsoever. Moreover, SARs can be twice as high for young children as for adults (Wiart 2008), so that under the current radiation standards a young child can easily receive a level of radiation exposure at which adverse behavioral effects are observed in animals.

The approach that IEEE/FCC took to the development of the cell phone radiation standard stands in stark contrast to the risk management approach practiced by the Environmental Protection Agency (EPA). According to EPA, protective reference values should be derived in a way that accounts for both the uncertainty and the variability in the data available (U.S. EPA 2008). In this framework, variability refers to heterogeneity or diversity in the human population, such as different exposure frequencies and duration and differences in response such as genetic or age-specific difference in vulnerability to a particular physical, chemical, or biological agent. Further, uncertainty is typically due to a paucity of available information, for example, for extrapolation from animal data to humans, extrapolating from short-term to chronic exposure and lack of information on all health endpoints affected by the exposure (NRC 2008a; U.S. EPA 2002). To account for uncertainty and variability, one of several, generally 10-fold, default factors are used in EPA risk assessments for operationally deriving the reference exposure values from experimental data (U.S. EPA 2009).

The goal of applying the uncertainty/variability factors for developing general population exposure standards is to ensure that an adequate margin exists to protect infants, young children, and other vulnerable populations from harmful exposures. The choice of specific uncertainty factors (UF) depends on the quality of the studies available and the extent of the research database. EPA has developed certain general principles that apply to most risk assessments (U.S. EPA 2002):

  • Interspecies UF accounts for different sensitivity between humans and laboratory test species; it generally falls between 3 and 10, but factors more than 10 might also be applied;
  • Intraspecies UF accounts for variability in response between different people; this factor is generally set at 10 and needs to be higher so as to specifically protect children;
  • Subchronic-to-chronic duration UF is typically set at a default value of 10 whenever the results of a short-term exposure study are used to derive a long-term exposure standard;
  • Finally, for certain exposures during the vulnerable period of development, such as exposure of young children to pesticides, an additional safety factor of 10 is used (mandated under Food Quality Protection Act of 1996).

Of note, the development of the IEEE standard did not involve risk assessment and uncertainty factor considerations as applied by the EPA. A statement from a recent review on the history of the standard is very telling: “to account for uncertainties in the data and to increase confidence that the limits are below levels at which adverse effects could occur, somewhat arbitrary safety factors (typically 10-50) are applied to the established threshold” (Osepchuk 2003).

As described by the IEEE 2005 “Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields”, IEEE applies a safety factor of 10 for whole body exposure and adds an additional factor of 5 so as to “recognize public concerns and take into account uncertainties in laboratory data and in exposure assessment” (IEEE 2006). Why a factor of 5 and not 10, the default factor typically used by EPA in cases of uncertainty (U.S. EPA 2002)? According to IEEE, the International Committee on Electromagnetic Safety determined that “an additional factor of 10 was likely excessive and a factor of 2 not sufficiently differentiating from the upper tier” (IEEE 2006). IEEE has argued that even this 5-fold factor may be excessive and unnecessary and that exposure limits for the general population need to be set at the same higher level as for occupationally exposed people in the workplace (IEEE ICES 2002; Microwave News 2001). IEEE based this recommendation on an untested hypothesis that there would be no difference in sensitivity of different population subgroups to electromagnetic radiation (IEEE ICES 2002).

In its assessment, IEEE has sanctioned a 20-fold higher SAR values for the head (1.6 W/kg) than the whole-body exposure (0.08 W/kg). There are no scientific data to support this decision. As indicated in the authoritative assessment from the Radiofrequency Interagency Work Group (RFIAWG), a task force that included the National Institute for Occupational Safety and Health (NIOSH), EPA, FCC, Occupational Safety and Health Administration (OSHA), and the National Telecommunications and Information Administration, the brain may well be the most sensitive part of the human body with respect to radiofrequency radiation, and would require a more and not less protective standard (FDA 2008a; RFIAWG 1999).

Over the past several years, IEEE has been pressuring FCC to further relax the SAR standard for mobile phones, so that greater energy absorption into the head would be legally permitted (IEEE ICES 2002; Li 2006; Lin 2006; Microwave News 2001; Silva 2002). As promoted by the IEEE, the new upper limit for exposure to the head would be 2 W/kg instead of the FCC limit of 1.6 W/kg (IEEE 2006). The new IEEE standard (2006) also proposed to increase allowed SAR levels for the ear (“pinna”) from 1.6 W/kg to 4/0 W/kg, the same as current standards for hands, wrists, feet and ankles (IEEE 2006)

IEEE also proposed to switch to a method of SAR determination that involves averaging absorbed radiation over 10 g of tissue (IEEE 2006), even though it is well known that averaging over a greater volume tends to underestimate the SAR value by a factor of 2-3 (Cardis 2008; Gandhi 2002). Although so far this proposal has not been adopted by the FCC, in the past FCC had a disconcerting track record of accepting IEEE recommendations without peer review by an independent body of scientific experts (GAO 2001; Lin 2006).

U.S. cell phone certification is primarily carried out by private industry organizations

Cell phones certified by FCC for use in the U.S. must be shown to comply with the legal SAR limits. Yet, cell phone manufacturers opposed public SAR disclosure until 2000, when the FCC began posting cell phone SAR values on its web site (Lin 2000). After the FCC decision, the Cellular Telecommunications Industry Association (CTIA) began requiring manufacturers to disclose cell phone SARs.

It takes effort and persistence to locate the radiation emission (SAR) value for a cell phone either on the manufacturer’s website or in the FCC database. There is no standard format for SAR disclosure by the manufacturers, so a search can be very time consuming. According to CTIA guidelines, a mobile phone SAR value must be listed in the user manual or on a separate sheet. The trade association does not require listing the SAR value on the box or the phone itself (Microwave News 2000).

The FCC Office of Engineering and Technology (OET) is the main division within the FCC responsible for cell phone certification and oversight of all radiofrequency equipment in general. FCC has several equipment approval programs, all of which involve the use of the private sector to varying degrees, including:

  • Verification (self-approved by the manufacturer). According to 47CFR 2.902, “Verification is a procedure where the manufacturer makes measurements or takes the necessary steps to insure that the equipment complies with the appropriate technical standards. Submittal of a sample unit or representative data to the Commission demonstrating compliance is not required unless specifically requested by the Commission”

  • Declaration of Conformity (manufacturer self-approved using an accredited lab). According to 47CFR 2.906, “Declaration of Conformity is a procedure where the responsible party, as defined in Sec. 2.909, makes measurements or takes other necessary steps to ensure that the equipment complies with the appropriate technical standards. Submittal of a sample unit or representative data to the Commission demonstrating compliance is not required unless specifically requested.”

  • Certification. According to 47CFR 2.906, “Certification is an equipment authorization issued by the Commission, based on representations and test data submitted by the applicant”.

Certification of a cell phone or any other type of device can be approved by the FCC or a Telecommunication Certification Body (TCB), which is a private industry certification organization. As described in 47CFR 2.960, “The Commission may designate Telecommunication Certification Bodies (TCBs) to approve equipment as required under this part. Certification of equipment by a TCB shall be based on an application with all the information specified in this part. The TCB shall process the application to determine whether the product meets the Commission's requirements and shall issue a written grant of equipment authorization. The grant shall identify the TCB and the source of authority for issuing it.”

According to the FCC, “A TCB is a private organization, which is authorized to issue grants, within its scope of designation, for equipment subject to the FCC’s certification procedure. Under these rules, a TCB has the authority to review and grant an application for certification to the FCC rules” (FCC OET 2008f). Examples of devices that can receive certification either through the FCC or through a TCB include cell phones; radiofreqency lights; microwave ovens; family radio; telemetry transmitters; walkie talkies (FCC OET 2008c). Of note, the rules for FCC-TCB interaction are not listed in 47CFR. As described by an FCC representative in a conversation with EWG on April 1, 2009, FCC-TCB interaction is a "constantly developing process." Typically, FCC gives new guidelines to TCBs on an ongoing basis, usually in the format of TCB workshops held 2-3 times a year (FCC OET 2005a, b, 2006, 2008a).

Considering the widespread use of cell phones and other wireless communication devices, it is surprising that the vast majority of them do not undergo direct FCC review. FCC has defended the use of the private sector for certification and issuing grants of equipment authorization, stating that in the Agency’s opinion, a private certification system allows for rapid adjustment to changing technology with shorter product life cycles; faster product approvals; access to technical expertise and ability to certify equipment; increase in resources performing conformity assessment; efficiencies in designing and approving products in the same geographic location; as well as reduced uncertainty and delay in obtaining certification (FCC OET 2005a). However, multiple issues of oversight, conflict of interest, adequate auditing and public disclosure hamper the transparency of the TCB certifications (GAO 2001).

In the TCB process, the manufacturer, an accredited lab, or a TCB can test the SAR value of a sample phone. A TCB then reviews the mobile phone test data and application for compliance. The application must demonstrate concordance with the FCC limits (47CFR2.1093(d)) for the phone to receive equipment authorization. If the review is favorable, TCB enters the product into the FCC database and FCC issues a so-called “grant of equipment authorization” within a few days. The TCB uploads supporting information to the FCC site electronically and FCC does not review the materials before the grant of equipment authorization is issued. The manufacturer pays application fees to the TCB fees but not the FCC (FCC OET 2005a, 2008g).

A path for manufacturer application directly to FCC also exists. This path involves FCC fees, FCC examiner review and FCC engineer review. If no problems or questions arise during the FCC review, the agency issues a grant of equipment authorization in about 30-45 days from when the application was received; the process may be delayed depending on potential FCC queries (FCC OET 2005a).

Over 100 FCC-recognized TCBs exist in the U.S. alone, and the number of international FCC-recognized TCBs is much greater (FCC OET 2009). While statistics specific for mobile phones’ equipment authorization are not publicly available, in 2005, from over 7000 applications for radiofrequency equipment authorization, fewer than 1000 grants were authorized by the FCC and the rest of the applications were authorized by TCBs (FCC OET 2006). In 2006 and 2007, the number of TCB-authorized applications continued to rise to over 9000 in 2007, while the number of FCC-authorized applications remained around 500 (~ 5% of the total) (FCC OET 2008e). Specific statistics for cell phones are not available. However, statements from TCB suggest that majority of cell phones go through TCB certification, as illustrated by a representative quote from the website of Intertec, an accredited TCB:

“The FCC has designated Telecommunication Certification Bodies (TCB) to certify products for the FCC in a shorter timeframe, allowing manufacturers like you to get to market quicker. Intertek is a TCB and can help you with your FCC testing and certification in less than half the time it takes the FCC…. Partnering with Intertek for both FCC Testing and FCC Certification saves both time and money… We have expert TCB reviewers throughout the United States and Asia, enabling fast, simple, and convenient FCC testing and certification for manufacturers around the globe… Our reviewers have undergone detailed TCB training from the FCC, and they maintain a continuing education program with the FCC to stay abreast of any changes that may occur to any Part of the Rules. Each reviewer has had significant hands-on experience performing FCC tests and preparing their own applications to the FCC. We can issue your certification within days, not months. The FCC currently averages 35 days to issue certification. Since time-to-market is such a critical factor, that’s a risk not worth taking. With TCB reviewers around the world and direct links to forms and guides to help you with the process, Intertek is the answer for quick and accurate FCC testing and certification.” (Intertec 2009)

While the FCC has authority to audit any grants of equipment authorization and conduct its own verification, this happens very rarely. In 2005, FCC established an Audit and Compliance Branch within the OET Laboratory Division in order to test and evaluate various types of authorized equipment and perform TCB audits (FCC OET 2005b, c, 2008d). Initially, the Audit and Compliance branch was tasked with auditing 20% of TCB Grants; sampling and testing 2% of of the total number of products approved by TCB for a given year (FCC OET 2005b). This degree of oversight was soon found by the Commission to be insufficient and, in October 2008, FCC introduced a new set of rules for internal auditing programs that TCBs need to carry out (FCC OET 2008a). The surveillance sample amount was raised to 5% of authorized equipment, including 1% of grants for wireless devices that are subject to SAR measurements (FCC OET 2008a).

TCBs are also required to conduct post-market surveillance, auditing at least 5% of the total number of products certified by the TCB. For post-market testing, TCBs can obtain samples by requesting a grantee to submit a sample of the product certified or by purchasing a sample of the product from the marketplace. The TCB must file with the FCC an annual summary of all surveillance audits performed, and TCBs are required to notify FCC if a violation is detected (FCC OET 2008h). However, as EWG found out in a conversation with FCC Auditing and Compliance Branch on April 1, 2009, FCC does not store the audit information, and TCBs are not required to submit the actual results of their audits to FCC; in fact, auditing data are considered to be TCB's proprietary information.

Under the 47CFR rules and regulations, FCC can request a TCB to provide reports of surveillance activities carried out by the TCB or to test samples of products certified by the TCB. Occasionally, FCC conducts independent testing, usually in response to a complaint from the field. If a non-compliance or violation instance is detected, such as inappropriate radiofrequency channel use or electromagnetic interference with medical devices (FCC 2009; FCC OET 2008a, h), the FCC Enforcement Bureau (http://www.fcc.gov/eb/) has the authority to issue a wide range of sanctions (FCC OET 2008a). In a conversation with EWG on April 1, 2009, FCC officials indicated that cell phone radiation emissions are generally not a subject of violations enforcement, since, in the opinion of FCC, these types of issues are resolved during the TCB/FCC certification process.