Spearman correlation of amplitudes of DPOAEs against areas under the curve (AUCs) calculated for 3 months time intervals after approximation of single time point PCB 153 serum concentration data with mathematical function. Children were audiologically examined at the age of 45 months. On horizontal axis are shown AUCs and on the vertical parameters of Spearman correlation ρ and its p value. Squares denote Spearman correlation coefficient and diamonds its direction. Full squares denote statistical significance at p < 0.05, full triangles at p < 0.1, empty squares p > 0.1. A. All children, right ears. B. All children, left ears. C. Boys, right ears. D. Boys, left ears.