To protect people from Electromagnetic Fields (EMF), ICNIRP has defined limits. The fundamental ones are the Basic Restrictions (BRs) [1]. The BRs determine the maximum values (averaged over the whole body and averaged over 10 grams of tissues) of Specific Absorption Rate (SAR). Since BRs can be complex to assess ICNIRP has also defined derived value: the reference levels (RLs). These RLs were established to guaranty the compliance to the BRs. Several studies with human model voxels (a.k.a. phantoms) show that even below the RLs, the WBSAR (Whole Body average SAR) may exceed the BRs due to the variability of human morphology [2]. In this paper we will identify the morphological factors influencing the WBSAR in the case of a frontal plane wave exposure at the frequency of 2100MHz in isolated conditions and vertical polar. The method is based on the construction of a model that makes it possible to estimate the statistical distribution of the WBSAR for a given human population.