In ESR dating of Early Pleistocene fossil tooth enamel samples, the fitting function used for the evaluation of the DE value is undoubtedly among the major sources of uncertainty. Dose recovery tests performed on fossil tooth enamel showing DE values >1,000 Gy demonstrate: (i) that high precision ESR measurements (<0.5%) and high DE reproducibility (<5%) may be achieved; (ii) the appropriateness of the Double Saturating Exponential (DSE) fitting function for ESR dose reconstruction. In contrast, the SSE function, which has been almost exclusively used so far, does simply not correctly describe the behavior of the radiation induced ESR signal of tooth enamel with the dose.

Several fitting functions and data weighting options were tested and the combination of a DSE with data weighted by the inverse of the squared intensities is the procedure providing the most accurate DE results. However, the SSE may nevertheless sometimes produce consistent results if Dmax does not exceed 6*DE. Further work is required in that direction in order to determine more precisely in which conditions the SSE could be used as a fair approximation of the DSE function for these samples.