EVALUATION OF MOBILE EVALUATION OF MOBILE PHONE EXPOSURE PHONE EXPOSURE VARIATIONVARIATION

May 18, 2006AIHce 2006, Chicago, ILM. Shum, M. Kelsh, C. Sulser, M. McNeely, N. Kuster, J. Fröhlich,A.R. SheppardFunded by CTIA with Technical Oversight from FDA

Asher Sheppard Consulting

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Background Background

•• Widespread cell phone useWidespread cell phone use•• Ongoing epidemiologic studiesOngoing epidemiologic studies

–– IARCIARC–– Need for better understanding of exposureNeed for better understanding of exposure–– Particularly variation in exposureParticularly variation in exposure

•• Comprehensive cell phone exposure Comprehensive cell phone exposure assessment research project assessment research project –– Recall study Recall study –– Software Modified Phone surveys Software Modified Phone surveys –– Analysis of FCC Maximum SAR compliance Analysis of FCC Maximum SAR compliance

datadata–– Field StudyField Study

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Background Background (continued)(continued)

•• FCC SAR data have limitations in FCC SAR data have limitations in assessing assessing ““realreal”” world exposuresworld exposures–– Only measures maximum SAR Only measures maximum SAR –– Variation in power control will likely impact Variation in power control will likely impact

user exposure user exposure •• Current SMP studies only address one Current SMP studies only address one

technology: GSM technology: GSM –– U.S. cell phone service used and still uses U.S. cell phone service used and still uses

other technologies (e.g. TDMA, CDMA, other technologies (e.g. TDMA, CDMA, Analog) Analog)

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Study ObjectivesStudy Objectives

•• Collect Collect ““stagedstaged”” SARSAR•• Assess potential effects ofAssess potential effects of

–– Provider technologyProvider technology–– Region (proxy for base station density) Region (proxy for base station density) –– Cell phone designCell phone design–– Moving vs. stationary samples Moving vs. stationary samples –– Environmental factors (e.g. foliage, terrain)Environmental factors (e.g. foliage, terrain)

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•• One EASY4 allows data acquisition from probes at One EASY4 allows data acquisition from probes at high sampling rates; PChigh sampling rates; PC--controlledcontrolled

•• ITIT’’IS developed portable phantom system that could IS developed portable phantom system that could take readings from a car or vantake readings from a car or van

Instrumentation: SYNEHA Instrumentation: SYNEHA

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Data AcquisitionData Acquisition

•• Three phantom headsThree phantom heads–– 10 mm, 14 mm, and 30 mm dipole lengths (to match 10 mm, 14 mm, and 30 mm dipole lengths (to match

phone output power)phone output power)•• SYNEHA SYNEHA –– data recording and analysis data recording and analysis

systemsystem–– Simultaneously measures radiated power from four Simultaneously measures radiated power from four

mobile phones, (two each on two phantom heads) mobile phones, (two each on two phantom heads) –– Third phantom with two Third phantom with two SMPsSMPs (Motorola (Motorola TimeportTimeport

P7389) capable of recording power control at 2.5 s P7389) capable of recording power control at 2.5 s intervals independently of SYNEHA intervals independently of SYNEHA

•• Van used to collect data while driving and in Van used to collect data while driving and in stationary positions across three distinct stationary positions across three distinct routes in San Francisco Bay Arearoutes in San Francisco Bay Area

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Van Photos with SYNEHA and Van Photos with SYNEHA and PhantomsPhantoms

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Parameters EvaluatedParameters Evaluated•• TechnologyTechnology

–– GSM (1900 MHz), GSM (1900 MHz), –– CDMA, TDMA, and Analog (850 MHz)CDMA, TDMA, and Analog (850 MHz)

•• Type of Geographic Region (Proxy for Base Type of Geographic Region (Proxy for Base station density)station density)–– Urban (San Francisco)Urban (San Francisco)–– Suburban (Peninsula)Suburban (Peninsula)–– Rural Rural

•• Cellular trafficCellular traffic–– Time of DayTime of Day

•• Type of phoneType of phone–– Flip/brickFlip/brick–– ModelModel

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Data Collection RoutesData Collection Routes

•• Urban (San Francisco)Urban (San Francisco)–– Financial district in downtown San FranciscoFinancial district in downtown San Francisco–– High rise, dense urban environment High rise, dense urban environment

•• Suburban (Peninsula)Suburban (Peninsula)–– Mixed commercial and residential Mixed commercial and residential –– One section One section –– relatively dense foliage relatively dense foliage

•• RuralRural–– ~100 miles south of San Francisco ~100 miles south of San Francisco –– Agricultural use area Agricultural use area –– Identified by carriers as low coverage areaIdentified by carriers as low coverage area

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Sampling StrategySampling Strategy

•• Phase I Phase I –– Evaluate impacts of base Evaluate impacts of base station density, technologystation density, technology

•• Phase II Phase II –– Evaluate cellular traffic Evaluate cellular traffic impactsimpacts

•• Phase III Phase III –– Evaluate different phonesEvaluate different phones

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Data Collection Data Collection

•• 2020––30 minute route30 minute route–– Measurements collected while van travels Measurements collected while van travels

across routeacross route–– Stationary measurement made for 2Stationary measurement made for 2––6 6

minutes during driveminutes during drive•• Minimize cross talk with phone Minimize cross talk with phone

positioning on headspositioning on heads•• Simulate conversation to address DTXSimulate conversation to address DTX•• Record GPS position simultaneous to Record GPS position simultaneous to

SYNEHA data collectionSYNEHA data collection

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Average Power by Technology (dBm)

10.6010.602.002.0014.3114.314.914.91InterquartileInterquartileRangeRange

25.8825.8817.6617.6613.4313.4329.0129.01MaximumMaximum

11.2211.22--12.4112.41--17.2617.2619.3519.35MinimumMinimum

5.375.375.405.408.248.243.023.02Std. Dev.Std. Dev.

16.1016.1015.3615.362.362.3624.1024.10MedianMedian

18.2318.2314.1114.11--0.380.3822.3422.34MeanMean

2626686892922222N (trips)N (trips)

TDMATDMAGSMGSMCDMACDMAAnalogAnalog

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Summary: Average Power By Technology Summary: Average Power By Technology and Routeand Route

-30

-20

-10

0

10

20

30

40

Rural Suburban Urban

Region

Ave

rage

dBm Analogue

GSMTDMACDMA

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ANOVA Results: Unbalanced DesignANOVA Results: Unbalanced Design

<0.0001<0.00015.85.87.37.343.543.566Technology Technology ** RouteRoute

<0.0001<0.000150.250.263.163.1126.3126.322RouteRoute

< 0.0001< 0.0001195.7195.7246.2246.2738.7738.733TechnologyTechnology

PP--ValueValueF ValueF Value

Mean Mean Sum of Sum of

SquaresSquares

Total Sum Total Sum of of

SquaresSquaresDFDF

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Summary Results of Average Power (dBm) by GSM Phone Model

3.243.241.251.250.660.66InterquartileInterquartileRangeRange

25.1825.1826.3126.3124.7124.71MaximumMaximum

9.679.6719.6419.6422.2622.26MinimumMinimum

5.355.351.661.660.800.80Std. Dev.Std. Dev.

24.2224.2224.3824.3824.3224.32MedianMedian

21.9421.9423.8423.8424.0924.09MeanMean

88414188NN

Nokia 5190 Nokia 5190 ((CandybarCandybar))

TimeportTimeport (SMP) (SMP) ((CandybarCandybar))

Motorola V60 Motorola V60 (Flip)(Flip)

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Source:

Sample Data Sample Data –– Urban Route Urban Route GSM GSM Technology MTP, 10.5 min data periodTechnology MTP, 10.5 min data period

AM

PL

ITU

DE

AM

PL

ITU

DE

TIME (ms)TIME (ms)0 3x105 9x1056x105

30

20

10

0

-10

Note: X-axis major tic marks = 5 minutes; X-axis minor tic marks = 1 minute

17Note: X-axis major tic marks = 5 minutes; X-axis minor tic marks = 1 minuteSource:

AM

PL

ITU

DE

AM

PL

ITU

DE

TIME (ms)TIME (ms)0 3x105 9x1056x105

Sample Data Sample Data –– Urban Route Urban Route Analog Analog Technology STTechnology ST , 11 min data period, 11 min data period

25

20

15

10

5

18 Source:

Sample Data Sample Data –– Urban Route Urban Route TDMA TDMA Technology ST, 9 min data periodTechnology ST, 9 min data period

30

20

10

0

AM

PL

ITU

DE

AM

PL

ITU

DE

TIME (ms)TIME (ms)0 3x105 6x105

Note: X-axis major tic marks = 5 minutes; X-axis minor tic marks = 1 minute

19 Source:

Sample Data Sample Data –– Urban Route Urban Route CDMA CDMA Technology V60, 11 min data periodTechnology V60, 11 min data period

AM

PL

ITU

DE

AM

PL

ITU

DE

TIME (ms)TIME (ms)

25

0

-25

-50

-750 3x105 9x1056x105

Note: X-axis major tic marks = 5 minutes; X-axis minor tic marks = 1 minute

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Time of Day (SMP only) Time of Day (SMP only) -- RuralRuralAverage and Standard Deviation of Rural Power Settings by Time of Day

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

Morning:8am to 9am

Morning:9am to 10am

Morning:10am to

11am

Mid-day:11am to

12pm

Mid-day:12pm to 1pm

Mid-day:1pm to 2pm

Afternoon:2pm to 3pm

Afternoon:3pm to 4pm

Afternoon:4pm to 5pm

Time of Day

Ave

rage

Pow

er S

ettin

g (W

)

Error bars represent the standard deviation

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Time of Day Time of Day -- SuburbanSuburbanAverage and Standard Deviation of Suburban Power Settings

by Time of Day

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

1.10

1.20

Morning

: 8am

to 9a

m

Morning

: 9am

to 10

am

Morning

: 10a

m to 11

am

Mid-da

y: 11

am to

12pm

Mid-da

y: 12

pm to

1pm

Mid-da

y: 1p

m to 2p

m

Afterno

on: 2

pm to

3pm

Afterno

on: 3

pm to

4pm

Afterno

on: 4

pm to

5pm

Evenin

g: 5p

m to 6p

m

Evenin

g: 6p

m to 7p

m

Evenin

g: 7p

m to 8p

m

Evenin

g: 8p

m to 9p

m

Evenin

g: 9p

m to 10

pm

Evenin

g: 10

pm to

11pm

Evenin

g: 11

pm to

12am

Time of Day

Ave

rage

Pow

er S

ettin

g (W

)

Error bars represent the standard deviation

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Time of Day Time of Day -- UrbanUrbanAverage and Standard Deviation of Urban Power Settings by

Time of Day

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

Morning:8am to

9am

Morning:9am to10am

Morning:10am to11am

Mid-day:11am to12pm

Mid-day:12pm to

1pm

Mid-day:1pm to

2pm

Afternoon:2pm to

3pm

Afternoon:3pm to

4pm

Afternoon:4pm to

5pm

Evening:5pm to

6pm

Time of Day

Ave

rage

Pow

er S

ettin

g (W

)

Error bars represent the standard deviation

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Summary of DataSummary of Data•• Amplitude measurements need conversion Amplitude measurements need conversion

to SAR valuesto SAR values•• Technology an important factor Technology an important factor

–– CDMA consistently lower CDMA consistently lower –– Analog always higher Analog always higher –– GSM and TDMA in between GSM and TDMA in between

•• GSM dominated by handovers GSM dominated by handovers •• RegionRegion

–– Rural route has highest power levelsRural route has highest power levels–– Urban, except for TDMA, consistently lower power Urban, except for TDMA, consistently lower power

levelslevels•• Phone Type Phone Type –– Limited data, but no great differencesLimited data, but no great differences

•• Time of Day Time of Day -- No clear differences, higher in mornings?No clear differences, higher in mornings?

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DiscussionDiscussion

•• First available comparative data across First available comparative data across different service technologiesdifferent service technologies

•• SYNEHA data not consistent with FCC SYNEHA data not consistent with FCC data of maximum SARsdata of maximum SARs–– FCC FCC –– Analog>CDMA>GSM>TDMA for 800 Analog>CDMA>GSM>TDMA for 800

MHz MHz –– SYNEHA SYNEHA –– CDMA clearly the lowestCDMA clearly the lowest

•• SMP data SMP data –– time of day does not time of day does not appear to be important exposure appear to be important exposure variablevariable

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Next StepsNext Steps

•• TranslateTranslate power measurements to SARpower measurements to SAR•• Analyze all field data for time of day Analyze all field data for time of day

trendstrends•• Compare GSM and SMP data to Compare GSM and SMP data to

determine correlationdetermine correlation•• Confirm handovers with trace data Confirm handovers with trace data

provided by carriersprovided by carriers•• Final report Final report –– implication of findings implication of findings

for epidemiologic studiesfor epidemiologic studies

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AcknowledgementsAcknowledgements

•• Funding: Cellular Telecommunications Funding: Cellular Telecommunications and Internet Association (CTIA) and Internet Association (CTIA)

•• Scientific oversight: Center for Devices Scientific oversight: Center for Devices and Radiological Health of the U.S. Food and Radiological Health of the U.S. Food and Drug Administration (FDA) Under a and Drug Administration (FDA) Under a Collaborative Research and Development Collaborative Research and Development Agreement (CRADA) Agreement (CRADA)

•• Exposure Assessment Panel: Joseph Exposure Assessment Panel: Joseph Bowman, Richard Tell, Bowman, Richard Tell, DimitriosDimitriosTrichopoulosTrichopoulos, Joe , Joe Wiart Wiart

•• Motorola: Joe MorrisseyMotorola: Joe Morrissey

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