Study overviews

Genotoxicity is defined as the mutagenic potential of an agent to cause changes in the genetic material (DNA/RNA) of cells and/or to damage the genome. However, this term is seen from a purely experimental point of view, how agents act in appropriate experiments. Positively tested agents or chemicals are not necessarily carcinogenic, since carcinogenesis is a long-term and multi-level process and results of in vitro or animal studies can not be transferred to humans without restrictions. Humans and other higher organisms have extensive metabolic pathways for detoxification (for EMF not relevant) as well as effective DNA repair mechanisms.

The following test systems and investigations are frequently applied in the context of the determination of genotoxic effects of electromagnetic fields:

• Investigation of chromosome aberrations
• investigation of sister chromatid exchange frequency
• comet assay
• micronucleus assay

For the evaluation of possible genotoxic effects of electromagnetic fields there are no prescribed or recommended evaluated test systems, in contrast to the classical toxicity determination of chemicals, which results in turn in a broad heterogeneity of the studies (see table). The studies differ greatly with respect to their frequency ranges (835 to 1900 MHz), the different types of modulation (TDMA, CDMA, FDMA, etc.) and SAR values (0.005 to 10 W/kg) as well as the different applied cell systems and investigated measurement parameters (chromosome alteration, sister chromatid exchange, micronuclei formation, DNA stability, DNA strand breaks). The European REFLEX project was established to harmonize appropriate investigations.

Out of the 60 studies available (as of March 2009), 48 are in vitro studies, i.e. studies dealing with established cell culture systems, blood lymphocytes, pure DNA samples or similar laboratory systems. The twelve remaining studies investigate DNA samples following in vivo exposure, i.e. experimental animals were irradiated under standardized laboratory conditions or blood samples were taken of humans being exposed residentially or occupationally and their DNA was studied. In 40% (20 studies) of all in vitro studies, at least one parameter of different other parameters was found to be positive, indicating a genotoxic effect following mobile phone related exposure. However, it is important to note that detected effects are often thermal in nature, the effects are only seen transiently being repaired during the course of time (DNA repair) or they appear only together with other genotoxic agents (co-exposure). It must also be taken into consideration that there are still many other parameters remaining that do not indicate a genotoxic effect. Finally, it is important to note that it is easier to publish studies inferring a positive effect than studies showing no effect (so-called publication bias).

Taking all of the aforementioned factors into account, the review of health effects due to mobile phone-related frequencies is a demanding and time-consuming process even if the physical, biological and medical expert knowledge is available. In the course of this process, all publications of all study designs (in vitro, in vivo or epidemiological) dealing with a defined EMF frequency range and a particular biological or medical endpoint have to be collected and individually evaluated in respect to their quality (e.g. dosimetry, study design, sample size, statistics), reproducibility of the data and comparability with other studies.

In Germany, the Strahlenschutzkomission (Commission for Radiation Protection, SSK) at the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit, BMU) also provides statements on the effects of electromagnetic fields. In statements from 2006 and 2009 on the effects of radiofrequency electromagnetic fields on the genome (genotoxicity and gene regulation), the commission concludes the literature provides no evidence for genotoxic effects caused by radiofrequency electromagnetic fields.

At the international level, particularly the WHO is responsible for statements on the effects of electromagnetic fields. For public health related issues specific recommendations are available.

In Germany, the Federal Office for Radiation Protection (Bundesamt für Strahlenschutz, BfS) is the responsible authority. They also provide specific statements on the effects of electromagnetic fields.

Genotoxic effects of electromagnetic fields in the frequency range of mobile phones are reviewed and evaluated by different experts within the following articles:

• Verschaeve et al. 2010
• Phillips et al. 2009
• Ruediger 2009
• Verschaeve 2009
• Vijayalaxmi and Prihoda, 2008
• Verschaeve 2005
• Moulder et al. 2005
• Vijayalaxmi and Obe, 2004
• Heynick et al. 2003
• Frumkin et al. 2001
• Carlo and Jenrow, (2000)