As of June 30, 2007, the French Regulatory Authority for Electronic Communications and Postal Services (Arcep, formerly known as ART) reported more than 52 million mobile phone subscribers in France, demonstrating just how much an integral part of our daily lives mobile phones have become. However, mobile telephony—or rather, certain aspects of it—continues to raise concerns among the public. Exposure limit values for human exposure to electromagnetic fields were proposed in 1998 by the International Commission on Non-Ionizing Radiation Protection (ICNIRP), which is the international scientific commission recognized by the World Health Organization (WHO) as the authority in the field of non-ionizing radiation. These exposure limit values were incorporated into Council Recommendation 1999/519/EC of July 12, 1999, on public exposure to electromagnetic fields, and by France in Decree 2002-775 of May 3, 2002. These limit values were established based on the lowest exposure levels at which biological and health effects were observed in laboratory animals, as well as on a comprehensive analysis of available scientific knowledge. The biological effect observed in animals at the lowest exposure level is a thermal effect resulting in behavioral changes. To account for potential uncertainties and variability in population sensitivity, and to provide a safety margin, a 50% reduction factor is applied to these exposure levels to define the public exposure limit values.[chapter excerpt]