How to combine the use of different mobile and cordless telephones in epidemiological studies on brain tumours?

Mobile phone users in epidemiological studies have often used more than one phone model, and sometimes also more than one mobile phone system (analogue and digital systems). Until now, this has not been taken into account in epidemiological studies, mainly because we do not know the possible interaction mechanism(s) and, hence, how to integrate exposure from different phones into one dosimetric measure. In this paper we take a step towards starting a discussion about how to proceed with this important issue and the possible use of parameters such as weighting factors, measured specific absorption rate (SAR) values and integrated specific absorption values are discussed. As a base of this discussion two previously published studies are used, one on mobile phones and cancer and the other one on subjective symptoms.