Epidemiological study (observational study)

Pooled analysis of two case-control studies on use of cellular and cordless telephones and the risk for malignant brain tumours diagnosed in 1997-2003 epidem.

By: Hardell L, Carlberg M, Hansson Mild K

Published in: Int Arch Occup Environ Health 2006; 79 (8): 630-639

Aim of study (acc. to author)

A pooled analysis of two previous case-control studies on the use of cellular and cordless telephones and the risk of malignant brain tumors was conducted in Sweden.

Further details

The first case-control study regarding the period 1997-2000 was published in the publications 9520 and 9895, the second study regarding the period 2000-2003 in publications 12068 and 12259.

Endpoint/type of risk estimation

brain tumor: malignant brain tumors

Type of risk estimation:

incidence

(odds ratio (OR))

Exposure

- mobile communications
- analog mobile phone
- digital mobile phone
- cordless phone
- personal

Assessment

questionnaire: first year of use, type of phone, mean minutes of daily use over the years, use in a car with external antenna or a hands-free, ear most frequently used
interview: supplementing data

Exposure groups

Group	Description
Reference group 1	unexposed
Group 2	analog, cumulative lifetime use: 1- 1,000 hours
Group 3	analog, cumulative lifetime use: 1,001 - 2,000 hours
Group 4	analog, cumulative lifetime use: > 2,000 hours
Group 5	digital, cumulative lifetime use: 1- 1,000 hours
Group 6	digital, cumulative lifetime use: 1,001 - 2,000 hours
Group 7	digital, cumulative lifetime use: > 2,000 hours
Group 8	cordless, cumulative lifetime use: 1- 1,000 hours
Group 9	cordless, cumulative lifetime use: 1,001 - 2,000 hours
Group 10	cordless, cumulative lifetime use: ≥ 2,000 hours
Group 11	analog > 1- to 5-year latency period
Group 12	analog > 5- to 10-year latency period
Group 13	analog > 10-year latency period
Group 14	analog total, > 1-year latency period
Group 15	analog ≤ 85 h, > 1- to 5-year latency period
Group 16	analog ≤ 85 h, > 5- to 10-year latency period
Group 17	analog ≤ 85 h, > 10-year latency period
Group 18	analog ≤ 85 h, total, > 1-year latency period
Group 19	analog > 85 h, > 1- to 5-year latency period
Group 20	analog > 85 h, > 5- to 10-year latency period
Group 21	analog > 85 h, > 10-year latency period
Group 22	analog > 85 h, total, > 1-year latency period
Group 23	digital > 1- to 5-year latency period
Group 24	digital > 5- to 10-year latency period
Group 25	digital > 10-year latency period
Group 26	digital total, > 1-year latency period
Group 27	digital ≤ 64 h, > 1- to 5-year latency period
Group 28	digital ≤ 64 h, > 5- to 10-year latency period
Group 29	digital ≤ 64 h, > 10-year latency period
Group 30	digital ≤ 64 h, total, > 1-year latency period
Group 31	digital > 64 h, > 1- to 5-year latency period
Group 32	digital > 64 h, > 5- to 10-year latency period
Group 33	digital > 64 h, > 10-year latency period
Group 34	digital > 64 h, total, > 1-year latency period
Group 35	cordless > 1- to 5-year latency period
Group 36	cordless > 5- to 10-year latency period
Group 37	cordless > 10-year latency period
Group 38	cordless total, > 1-year latency period
Group 39	cordless ≤ 195 h, > 1- to 5-year latency period
Group 40	cordless ≤ 195 h, > 5- to 10-year latency period
Group 41	cordless ≤ 195 h, > 10-year latency period
Group 42	cordless ≤ 195 h, total, > 1-year latency period
Group 43	cordless > 195 h, > 1- to 5-year latency period
Group 44	cordless > 195 h, > 5- to 10-year latency period
Group 45	cordless > 195 h, > 10-year latency period
Group 46	cordless > 195 h, total, > 1-year latency period

Population

Group:
- men
- women
Age: 20–80 years
Observation period: 1997 - 2003
Study location: Sweden (Uppsala/Örebro and Linköping medical regions 1997-2003, Stockholm and Gothenburg regions 1997-2000)

Case group

Characteristics: brain tumor, histopathologically verified
Data source: Cancer registry
Exclusion criteria: deceased, medical conditions

Control group

Selection:
- population-based
Matching:
- sex
- age
- area
- case:control = 1:1

Study size

	Cases	Controls
Eligible	1,008	2,437
Participants	905	2,162
Participation rate	90 %	89 %

Statistical analysis method:

unconditional logistic regression

(adjustment:

age
sex
socioeconomic status
year of diagnosis

)

Results (acc. to author)

The pooled analysis showed that use of cellular telephones and cordless telephones for more than 10 years significantly increased the risk for malignant brain tumors. The risk increased with cumulative lifetime number of hours of use.

Study funded by

Cancer och Allergifonden (Cancer and Allergy Foundation), Sweden
Cancerhjälpen (Cancerhelp), Sweden
Nyckelfonden, Sweden
Örebro Cancer Fund, Sweden

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