Mobile phones and head tumours. The discrepancies in cause-effect relationships in the epidemiological studies - how do they arise?

Abstract

BackgroundWhether or not there is a relationship between use of mobile phones (analogue and digital cellulars, and cordless) and head tumour risk (brain tumours, acoustic neuromas, and salivary gland tumours) is still a matter of debate; progress requires a critical analysis of the methodological elements necessary for an impartial evaluation of contradictory studies.MethodsA close examination of the protocols and results from all case-control and cohort studies, pooled- and meta-analyses on head tumour risk for mobile phone users was carried out, and for each study the elements necessary for evaluating its reliability were identified. In addition, new meta-analyses of the literature data were undertaken. These were limited to subjects with mobile phone latency time compatible with the progression of the examined tumours, and with analysis of the laterality of head tumour localisation corresponding to the habitual laterality of mobile phone use.ResultsBlind protocols, free from errors, bias, and financial conditioning factors, give positive results that reveal a cause-effect relationship between long-term mobile phone use or latency and statistically significant increase of ipsilateral head tumour risk, with biological plausibility. Non-blind protocols, which instead are affected by errors, bias, and financial conditioning factors, give negative results with systematic underestimate of such risk. However, also in these studies a statistically significant increase in risk of ipsilateral head tumours is quite common after more than 10 years of mobile phone use or latency. The meta-analyses, our included, examining only data on ipsilateral tumours in subjects using mobile phones since or for at least 10 years, show large and statistically significant increases in risk of ipsilateral brain gliomas and acoustic neuromas.ConclusionsOur analysis of the literature studies and of the results from meta-analyses of the significant data alone shows an almost doubling of the risk of head tumours induced by long-term mobile phone use or latency.

Mobile Phones and Head Tumours: A Critical Analysis of Case-Control Epidemiological Studies

“…We have already published a more detailed comparison of Hardell's and Interphone protocols and results [39]. Moreover, the results of our meta-analyses confirm that to determine true risk of head tumours due to MP radiation it is vital to identify the laterality of head tumour localisation relative to the habitual laterality of MP use, in subjects with at least 10 year use or latency of cellular and cordless phones.…”

“…In fact, the meta-analyses of Hardell [35,36], Khurana [37], Kundi [38], and ourselves [39], including the literature data on head tumours in people with MP latency or continuous use of at least 10 years -and thus, besides Hardell's data [1][2][3][4]36], also part of the Interphone data [23-25, 29, 31, 32] -show large and s.s. increases (100%) of the risk of ipsilateral gliomas with high level of malignancy, and sizable and s.s. increases (50-140%) of the risk of ipsilateral acoustic neuromas (Table 3). These increases are smaller than those found by Hardell in the pooled analyses of his data alone [1,2,4], being "diluted" with the Interphone data corresponding to the requirements indicated above.…”

Physical Health Hazards of Mobile Phone Use

“…It points out that blind protocols gave positive results suggesting a cause-effect relationship between longterm mobile phone use and increase of ipsilateral head tumor risk. The non-blind protocols, however, gave negative results with systematic underestimation of such risks [3].…”

“…Analysis conducted by Levis et al [3] suggests that most studies conducted to uncover the health risk of mobile telephones were subject to methodological fallacy. It points out that blind protocols gave positive results suggesting a cause-effect relationship between longterm mobile phone use and increase of ipsilateral head tumor risk.…”

Long-Term Effect of 900 MHz Radiofrequency Radiation Exposure on Cochlear Functions

“…there are many studies stating a possible correlation between mobile phone usage and central nervous system tumors (16). however, one of the important points to be considered should be focused on whether radiofrequencies emitted from mobile phones affect the hearing system.…”