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Epidemiological Study (case-control study)

Further aspects on cellular and cordless telephones and brain tumours. epidemiol.

By: Hardell L, Hansson Mild K, Carlberg M
Published in: Int J Oncol 2003; 22 (2): 399 - 407 ( open external web page PubMed Entry , open external web page Journal web site )

Aim of study (according to author)
In this study, further analyses were performed on the database of a Swedish case-control study (see publication 9105) on the use of cellular telephones and cordless telephones and the risk of brain tumors.
Background/further details:
Furthermore, there are additional analyses of the database of the same case-control study (publication 9105) published in publications 9361, 11953 and 12393.
Subjects without exposure to cellular phone or cordless phone were classified as unexposed.

Endpoint/type of risk estimation

Estimate of incidence by odds ratio (OR)


groups of exposure:

Reference group 1:  unexposed 
group 2:  analog, 450 MHz, > 1 year latency  
group 3:  analog, 450 MHz, > 5 years latency  
group 4:  analog, 450 MHz, > 10 years latency  
group 5:  analog, 900 MHz, > 1 year latency  
group 6:  analog, 900 MHz, > 5 years latency  
group 7:  analog, 900 MHz, > 10 years latency  
group 8:  analog, all, > 1 year latency  
group 9:  analog, all, > 5 years latency  
group 10:  analog, all, >10 years latency  
group 11:  analog, ≤ 85 h, > 1 year latency  
group 12:  analog, ≤ 85 h, > 5 years latency  
group 13:  analog, ≤ 85 h, >10 years latency  
group 14:  analog, > 85 h, > 1 year latency  
group 15:  analog, > 85 h, > 5 years latency  
group 16:  analog, > 85 h, > 10 years latency  
group 17:  digital, all, > 1 year latency  
group 18:  digital, all, > 5 years latency  
group 19:  digital, all, >10 years latency  
group 20:  digital, ≤ 55 h, > 1 year latency  
group 21:  digital, ≤ 55 h, > 5 years latency  
group 22:  digital, ≤ 55 h, >10 years latency  
group 23:  digital, > 55 h, > 1 year latency  
group 24:  digital, > 55 h, > 5 years latency  
group 25:  digital, > 55 h, >10 years latency  
group 26:  cordless, all, > 1 year latency 
group 27:  cordless, all, > 5 years latency 
group 28:  cordless, all, > 10 years latency 
group 29:  cordless, ≤ 183 h, > 1 year latency 
group 30:  cordless, ≤ 183 h, > 5 years latency 
group 31:  cordless, ≤ 183 h, > 10 years latency 
group 32:  cordless, > 183 h, > 1 year latency 
group 33:  cordless, > 183 h, > 5 years latency 
group 34:  cordless, > 183 h, > 10 years latency 
group 35:  analog, brain hemisphere ipsilateral 
group 36:  digital, brain hemisphere ipsilateral 
group 37:  cordless, brain hemisphere ipsilateral 
group 38:  analog, brain hemisphere contralateral 
group 40:  digital, brain hemisphere contralateral 
group 41:  cordless, brain hemisphere contralateral 
group 42:  analog, temporal area, ipsilateral 
group 43:  digital, temporal area, ipsilateral 
group 44:  cordless, temporal area, ipsilateral 
group 45:  analog, temporal area, contralateral 
group 46:  digital, temporal area, contralateral 
group 47:  cordless, temporal area, contralateral 


  • case group
    men and women, aged from 20 to 80 years
    diagnosis: brain tumor, histopathologically verified
    observation period: January 1997 - June 2000
    study location: Sweden (Uppsala/Örebro, Stockholm, Linköping and Göteborg regions)
    source of data: Cancer Registry
    exclusion criteria: deceased

  • control group
    selection: population-based
    matching: sex, area, 5-year age group, 1:1 (case:control)
Further parameters acquired by questionnaire (lifetime work history, exposure to ionizing radiation, different agents such as organic solvents, pesticides, asbestos, reproductive history for women and heredity)

Study size i cases  controls 
number eligible 1,617-
number contacted 1,6171,617
number participating 1,4291470
rate of participating 88%91%

Statistically significant results i

 group  exposure  endpoint  cases  controls  parameter (OR confidence interval 
8analog, all, > 1 year latency brain tumor2472181.31.04-1.6
35analog, brain hemisphere ipsilateralbrain tumor121731.71.2-2.3
36digital, brain hemisphere ipsilateralbrain tumor1821321.31.02-1.8
42analog, temporal area, ipsilateralbrain tumor41202.31.2-4.1

Statistical analysis using unconditional logistic regression (adjusted for age, sex, socioeconomic status)

Results/conclusion (according to author)
The results showed an increased risk of brain tumor for use of analog cellular phones, but not for digital cellular phones or cordless phones. The risk of brain tumor was increased among ipsilateral users of analog and digital cellular phones, also for users of cordless phones, but not significantly.

(Study character: epidemiological study, case-control study)

Study funded by

  • Cancer och Allergifonden (Cancer and Allergy Foundation), Sweden
  • Örebro Cancer Fund, Sweden
  • Swedish Work Environment Fund
  • Telia, Sweden

Related articles i
Glossary: analog, antenna, brain, brain tumor, cancer registry, case-control study, cellular phones, confidence interval, cordless phones, cumulative, digital, ear, endpoint, epidemiological, exposure, GSM, hemisphere, histopathologically, incidence, ionizing radiation, ipsilateral, latency, matching, mean, mobile communication, NMT, OR, organic, population-based, questionnaire, reproductive, risk, significantly, socioeconomic status, solvents, statistical, subjects, temporal, unconditional logistic regression
Exposure: mobile communication system, analog mobile phone, digital mobile phone, GSM, NMT, cordless phone, personal exposure

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