• Temperature rise (“heating”),

• voltage-gated ion channels (includes action potential-related channels),

• ion channel electro-denaturation,

• membrane enzyme electro-conformational coupling,

• magnetically sensitive radical pair reactions,

• magnetite-based mechanical coupling, and

• temporary membrane pore creation.

None of these possible mechanisms has so far been positively identified as a candidate for causation of health effect.

Testing for the sensitivity of the central nervous system (CNS) to detect modulated RF signals using the pattern recognition capability of the brain and neural networks would improve our understanding of the minimum signal level that biological systems can sense and distinguish from background noise.

It was noted at the workshop that mechanisms can be modeled theoretically with the use of software-based nonlinear cell models that describe field-induced molecular changes (Weaver 2007; Gowrishankar et al. 2006). It was also noted (D’Inzeo 2007) that investigation of doses occurring on the microscopic level may lead to a better understanding of possible interactions of RF electromagnetic fields on the cellular and subcellular level. The utility of this observation is supported by recent findings (Barnes and Kwan 2005) that suggest a higher energy absorption at the microscopic scale, e.g., at the boundary between cellular structures with different dielectric properties. Several national and international expert groups, including the World Health Organization, have requested more research into micro-dosimetry and appropriate dielectric models as a medium- to long-term research need. Some research programs in Europe already include such investigations.

It is unclear whether low-level RF exposure can trigger effects through stimulation of cellular thermo-receptors. It is also currently unclear if a nonlinear biological mechanism exists that could lead to demodulation effects. As a result, different modulations and wave characteristics would affect biological systems differently. There is some research with respect to this question underway, such as an experiment being conducted in the UK.⁸

Knowledge is lacking concerning the effects of electromagnetic fields on ion and molecular transport through the cell membrane. Work is ongoing at the Massachusetts Institute of Technology, and the outcome should be evaluated before further work is initiated (Weaver andChizmadzhev2006).