Frei P, Mohler E, Bürgi A, Fröhlich J, Neubauer G, Braun-Fahrländer C, Röösli M; The QUALIFEX Team. Classification of personal exposure to radio frequency electromagnetic fields (RF-EMF) for epidemiological research: Evaluation of different exposure assessment methods. Environ Int. Jun 8, 2010. Ahead of print.
Several exposure assessment studies have been conducted so far using exposimeters for the purpose of estimating exposure matrices for epidemiological studies. These dosimeters allow capture of exposure from all relevant radio frequency electromagnetic field exposure (RF-EMF) sources in the different environments where a study participant spends time. However, they are less apt to accurately measure exposure to personal mobile or cordless phones. This paper summarizes comprehensive RF-EMF exposure data collected from 166 participants in the QUALIFEX study, a prospective cohort study examining exposure to RF-EMF and health related quality of life.
The current analysis was aimed to investigate the impact of personal phone use on exposimeter readings and to evaluate different exposure assessment methods potentially useful in epidemiological studies.
In brief, RF-EMF measurements were collected from 166 volunteers living in the city of Basel, Switzerland and its surroundings between April 2007 and February 2008. RF-EMF exposure was measured using the personal exposimeter EME Spy 120. The study participants carried an exposimeter during one week, and completed a time activity diary, specifically recording place of stay and detailed use. Spot measurements were taken in the bedroom. Several models were used to estimate exposure. Appropriate statistical methods have been applied to quantify the impact of personal mobile and cordless phone use on mean values obtained from the exposimeter measurements.
The mean personal exposure was 0.13 mW/m2, when measurements during personal phone calls were excluded and 0.15 mW/m2, when such measurements were included.
The data suggest that a reliable discrimination of personal exposure levels to environmental far-field RF-EMFs measured with exposimeters is also made when measurements during personal mobile and cordless phone use are included. Using the geo-coded distance to the closest fixed site transmitter or self-estimated exposure is inappropriate, and may be poor surrogate for personal exposure. However, the latter can provide information on a possible information bias or nocebo effect.